Urine Volume Research Articles

Vasopressin-mediated water conservation overrides the osmotic-diuretic effect of glucosuria during SGLT2 inhibition in patients with chronic heart failure (DAPA-Shuttle1: a mechanistic placebo-controlled, randomized trial)

Background: SGLT2 inhibitors may improve cardiac outcomes due to their osmotic-diureticpotential. We prospectively tested the hypothesis that vasopressin-driven urine concentration overrides the osmotic-diuretic driving force of dapagliflozin-induced glucosuria.Methods: DAPA-Shuttle1 was an investigator-initiated, mechanistic, single-center, randomized controlled trial at the National Heart Centre, Singapore. Eligible participants with heart failure NYHA classes I/II and reduced ejection fraction were randomly assigned to receive dapagliflozin 10mg daily or placebo (1:1) for 4 weeks. Participants, investigators, and study personnel were masked to assignment throughout the trial. The primary endpoint was change from baseline in urine osmolyte concentration. Secondary endpoints included changes in copeptin levels, solute free water clearance (FWC), and tissue Na+ content.Results: Between November 2019 and September 2021 forty participants were enrolled. Thirty three randomized, SGLT2 inhibitors naïve participants started the treatment intervention and completed the study, of which (placebo: n=14; dapagliflozin: n=15) provided accurate 24h urine collections (mean age 59±14 years, LVEF 31±9%). Dapagliflozin treatment increased glucosuria by 3.3 mmol/kg/d ([95%CI 2.51,4.04], p<0.0001) within 48h (early); this effect persisted after 4 weeks (late; 2.7 mmol/kg/d [95%CI 1.98,3.5], p<0.0001). Dapagliflozin treatment neither increased natriuresis (early: P=0.68; late: P=0.64), nor changed tissue Na+ content (early: P=0.62; late: P=0.90). Despite sustained glucosuria, urine volume did not significantly increase with dapagliflozin (mean difference early: +2.8 ml/kg/d [95%CI -1.97,7.48], P=0.25; late: +0.9ml/kg/d [95%CI -3.83,5.62], P=0.70). Dapagliflozin treatment increased plasma copeptin early (+5.5 pmol/L [95%CI 0.45,10.5], p<0.05) and late (+7.8 pmol/L [95%CI 2.77,12.81], p<0.01), leading to proportional reductions in FWC (early: -9.1 ml/kg/d [95%CI -14, -4.12], p<0.001; late: -11.0 ml/kg [95%CI -15.94, -6.07], p<0.0001) and increases in urine concentration (late: +134 mmol/L [95%CI 39.28, 229.12], p<0.01). This physiological-adaptive water conservation mechanism prevented a glucose-driven increase 70 in urine volume of approximately ≍10 ml/kg/d · 75 kg = 750 ml/d.Conclusions: SGLT2 inhibition with dapagliflozin caused relevant glucosuria, but adaptive physiological, vasopressin-driven water conservation virtually eliminated the expected osmotic diuretic potential of the drug. Therefore, the presented mechanistic-experimental evidence does not support the hypothesis that the beneficial effects of SGLT2 inhibitors in patients with heart failure are attributable to chronic cardiac decongestion. The DAPA-Shuttle1 study was an investigator-initiated trial funded by Astra Zeneca via the Externally sponsored scientific research program (ESR-18-13712). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

FINERENONE TREATMENT PREVENTS GLOMERULAR DAMAGE AND RENAL INTERSTITIAL INFLAMMATION IN TYPE 1 DIABETIC RATS WITH CHRONIC KIDNEY DISEASE

Objective: Finerenone (FIN), a non-steroidal mineralocorticoid receptor antagonist, has shown a protective effect on kidney and cardiovascular damage progression in type 1 diabetic Munich Wistar Frömter rats with established chronic kidney disease (CKD). The gradual decline in kidney function in diabetic CKD is due to a thickening of glomerular and Bowman capsule basement membranes, mesangial matrix expansion, and tubulointerstitial fibrosis. In this study we aimed to characterize whether the renal protection of FIN is related to a decrease in kidney damage through histomorphological changes in diabetic MWF rats. Design and method: Diabetes was induced by a streptozotocin injection (15 mg/Kg, i.p.) together with exposure to a high fat/high sucrose (HF/HS) diet (MWF-D) for 6 weeks. The MWF-D-FIN group was additionally treated with 10 mg/Kg/day of FIN included in the HF/HS diet (n = 6/group). Morphometrical analysis of renal structural changes was performed under hematoxylin and eosin staining, and light microscopy. Matrix metalloproteinases (MMP)-2 and MMP-9 activities were determined by zymography. Results: MWF-D and MWF-D-EP rats exhibited significantly elevated glycemia, water intake, urine volume, glucosuria, and kidney weight compared to control MWF. Histological examination of kidney samples of MWF and MWF-D rats showed hypertrophic glomeruli with an increase of the glomerular tuft and the Bowman's space. These pathological alterations were prevented by FIN treatment. The percentage of glomerulosclerosis was significantly higher in MWF and MWF-D rats and 59% lower in the MWF-D-FIN group (p<0.001) whereas the glomerulosclerosis index was reduced to 33% by FIN (p<0.001). Moreover, MWF-D rats showed an increased interstitial inflammation index compared to MWF rats (p<0.001) which was reduced to 44% (p<0.001) in the MWF-D-FIN group. Since an increase in MMP-2 and MMP-9 activities are associated with fibrosis development, these were determined by zymography in kidney samples of all groups. Both MMP-2 and MMP-9 were significantly higher in MWF-D compared to MWF and decreased by FIN treatment. Conclusions: In conclusion FIN prevents the development of diabetic kidney damage due to a reduction in glomerular alterations and interstitial inflammation associated to an inhibition of MMP-2 and MMP-9 activities.

Predictive value of albumin-to-fibrinogen ratio for acute kidney injury in infants undergoing ventricular septal defect repair with cardiopulmonary bypass

To investigate the predictive value of albumin-to-fibrinogen ratio (AFR) for postoperative acute kidney injury (AKI) in infants with ventricular septal defect repair under cardiopulmonary bypass (CPB). A retrospective analysis was conducted on infants diagnosed with ventricular septal defect in Anhui Children's Hospital from January 2019 to July 2023. The infants were divided into AKI group and non-AKI group according to whether AKI occurred in hospital after operation. Demographic data, preoperative data, intraoperative data, postoperative data and laboratory results during CPB were collected. Multivariate Logistic regression analysis was used to find the factors of AKI after ventricular septal defect repair with CPB. Receiver operator characteristic curve (ROC curve) was drawn to analyze the predictive value of AFR for postoperative AKI after ventricular septal defect repair with CPB. A total of 215 children were collected, including 28 in AKI group and 187 in non-AKI group. There were no significant differences in age, gender, body weight, height, history of pneumonia and history of chronic heart failure between the two groups, but the left ventricular ejection fraction (LVEF) in the AKI group was significantly lower than that in the non-AKI group (0.526±0.028 vs. 0.538±0.030, P = 0.048). The duration of CPB (minutes: 74.1±12.1 vs. 65.8±11.3, P < 0.001), aortic cross-clamping (minutes: 41.7±9.7 vs. 37.2±9.4, P = 0.021) and hypothermic circulation arrest (21.4% vs. 8.6%, P = 0.047) in AKI group were significantly higher than those in non-AKI group, but there were no significant differences in the proportion of ultrafiltration and urine volume between the two groups. The length of intensive care unit (ICU) stay in AKI group was significantly longer than that in non-AKI group (days: 5.3±2.0 vs. 4.0±1.7, P < 0.001), but there were no significant differences in duration of mechanical ventilation and the proportion of postoperative hypotension between the two groups. During CPB, the levels of blood glucose (mmol/L: 9.4±1.3 vs. 8.8±0.8, P < 0.001), blood lactic acid (mmol/L: 2.2±0.3 vs. 2.0±0.3, P = 0.015) and serum creatinine (μmol/L: 79.7±11.5 vs. 74.4±10.9, P = 0.018) in AKI group were significantly higher than those in non-AKI group, while the AFR was significantly lower than that in non-AKI group (8.5±1.3 vs. 10.2±1.6, P < 0.001), but there were no significant differences in the levels of hemoglobin, blood urea nitrogen, alanine aminotransferase and aspartate aminotransferase between the two groups during CPB. Multivariate Logistic regression showed that AFR was a protective factor for AKI after ventricular septal defect repair with CPB [odds ratio (OR) = 0.439, 95% confidence interval (95%CI) was 0.288-0.669, P < 0.001]. Blood glucose (OR = 2.133, 95%CI was 1.239-3.672, P = 0.006) and blood lactic acid (OR = 5.568, 95%CI was 1.102-28.149, P = 0.038) were risk factors for AKI after ventricular septal defect repair with CPB. ROC curve analysis showed that the area under the curve (AUC) of AFR in predicting AKI after ventricular septal defect repair with CPB was 0.804 (95%CI was 0.712-0.897, P < 0.001). When the optimal cut-off value was less than 9.05, the corresponding sensitivity was 75.0% and the specificity was 72.7%. Low AFR (≤9.05) during CPB is an independent risk factor for AKI after ventricular septal defect repair with CPB. AFR during CPB has a high predictive value for postoperative AKI after ventricular septal defect repair with CPB.

Increases of renal sodium transporters before and after the occurrence of the hypertension in spontaneously hypertensive rats

Background: Adult spontaneously hypertensive rats (SHR) have increases of renal sodium transporters associated with hypertension. It remains to be determined whether the increases of renal sodium transporters are precede by occurrence of hypertension and reflected by urine exosomal sodium transporters that may serve as non-invasive biomarkers for the effcacy of anti-hypertensive drugs. Methods: 1. Male WKY rats and SHRs were aged of 4, 7 and 10 weeks respectively (n=5/group). 2. Additional 3 sets of 10-week-old rat (n=5/group) were administered by a 7-day intraperitoneal injections of furosemide (NKCC2 inhibitor, 5mg/kg), hydrochlorothiazide (NCC2 inhibitor, 30mg/kg) and amiloride (ENaC inhibitor, 10mg/kg) respectively. 3. The systolic blood pressure (SBP) was measured with a catheter in carotid artery of rats under anesthesia. Tail-cuff methods were used to monitor the drug responses. 4. All rats were rationally fed 0.4% NaCl agar-gelled diet for 7 days. 5. Exosomes were extracted with ultracentrifuge from the urines. Results: SHRs (4 weeks) exhibited similar SBP. The renal NKCC2, the major apical sodium transporters in thick ascending limb, was more than doubled in SHRs (215±14 % of WKY, student t-test, p&lt;0.05, same as below) while the other sodium transporters were normal. However, SHRs had a higher SBP than WKY at ages of 7 (157±10 vs 125±14, mmHg) and 10 weeks (192±8 vs 128±12). There were no differences for the all age groups in heart rate, body weight, urine volume, urine Na+ and Cl− excretion, and serum Cr, K+, Na+, and Cl− concentration between rat strains. At 10-weeks old, renal (161±24) and urine exosomal (159±21, corrected by UCr, same as below) NKCC2 were higher in SHR than WKY. Frusemide normalized SBP on day 1 (day 0: 190±18 vs 138±13; day 1: 149±13 vs 128±16) in SHR; Renal (129±9) and urine-exosomal (137±12) NCC were higher in SHR than WKY. Hydrochlorothiazide normalized SBP in SHR on day 1 (day 0: 206±4 vs 140±9; day 1: 159±11 vs 144±11). Renal (α:134±16; β:137±25) and urine-exosomal (α:153±13; β:158±12) ENaCs were higher in SHR than WKY. Amiloride diminished the difference in SBP between rat strains on day 1 (day 0: 188±18 vs 138±11; day 1: 164±16 vs 147±7). Conclusions: The increase of renal NKCC2 precedes the elevation of SBP in SHRs. Urine exosomal NKCC2, NCC, ENaCs may reflect their renal levels and be indicative of the corresponding inhibitors on the hypertension model. Natural Science Foundation of China 81970605. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Trimatch comparison of the prognosis of hypochloremia, normolchloremia and hyperchloremia in patients with septic shock

BackgroundSeptic shock is a lethal disease, and identifying high-risk patients through noninvasive and widely available biomarkers can help improve global outcomes. While the clinical impact of chloride levels on critically ill patients remains unclear, this study aims to investigate the association between hypochloremia and mortality following ICU admission among septic shock patients. MethodsThis is an analysis of data stored in the databases of Medical Information Mart for Intensive Care IV (MIMIC-IV). The initial chloride levels were classified ashypochloremia, normal chloraemia, and hyperchloraemia. A multivariate logistic regression model was applied, adjusting for age, lactate, pH, PO2, urine volume, RDW, creatinine, and liver disease, to assess the association between the three categories of chloride levels and mortality. ResultsOf 3726 patients included in the study, 470 patients (12.6%) had hypochloremia on ICU admission. During the follow-up period, 1120 (33.5%) patients died. Hypochloremia was significantly associated with increased mortality and the incidence of AKI after adjusting for several variables. ConclusionsHypochloremia is independently associated with higher hospital mortality, AKI incidence among septic shock patients. However, further high-quality research is necessary to establish the precise relationship between hypochloremia and septic shock prognosis.

A COMPARISON BETWEEN THE TWO METHODS OF MAGNESIUM SULFATE ADMINISTRATION FOR DURATION OF 12 VERSUS 24 H AFTER DELIVERY IN PATIENTS WITH SEVERE PREECLAMPSIA

Objective: Preeclampsia is one of the very serious and important complications of pregnancy which may culminate in serious maternal mortality and morbidity. For preventing eclampsia and convulsions, magnesium sulfate (Mg So4) is the medication of choice. As a standard method, it will be continued up to 24 hours after delivery of the baby. Shortening the duration of its administration can reduce the duration of hospital stay, risk of magnesium sulfate (Mg sulfate) toxicity and adverse effects, cost, duration of treatment, and patient satisfaction. The purpose of the present study was to compare the 2 methods of magnesium sulfate administration for a duration of 12 VS 24 hours after delivery in patients with severe preeclampsia. Design and method: The study was performed as a randomized clinical trial on 182 cases of severe preeclampsia. They were randomly assigned into the 2 groups. In one group, Mg sulfate was prescribed for 12 hours after delivery and in the other group, it was prescribed for 24 hours after delivery. The dosage of Mg sulfate was similar in both groups and only the duration of administration was different. Both groups were compared for the occurrence of convulsions and other adverse effects. Results: The women of the 2 groups did not have significant differences according to age, BMI, Parity, gravidity, or gestational age at the time of delivery. Also, systolic blood pressure, diastolic blood pressure, antihypertensive use, previous diabetes and renal disorders, gestational diabetes, and proteinuria were similar in both groups before treatment. One woman had a convulsion in the 12 hours group and Mg SO4 was continued for 24 hours in this case. Blood pressure, urine volume, and laboratory indexes did not show significant differences between the 2 groups before and after treatment. Also, adverse effects were similar in both groups. Pain at the injection site was less in the 12-hour group (P=0.048). Conclusions: Administration of Mg sulfate for 12 hours after delivery should be considered somehow as effective as 24 24-hour prescription for preventing convulsion after delivery.

Synergistic Effect of Naringin and Glimepiride in Streptozotocin-induced Diabetic Rats.

Evaluation of the synergistic effect of Naringin and Glimepiride in streptozotocin (STZ)-induced diabetic rats. Wistar rats were chosen and divided into five groups (n=6). STZ was used for the induction of diabetes. The combination of naringin and glimepiride was administered to diabetic rats. The changes in fasting blood sugar, body weight, Hb, HbA1c, and creatinine were evaluated, and urine was collected and the volume was observed. The lipid profiles like TC, HDL, LDL, and TG were measured. The biochemical parameters SGOT, SGPT, and ALP were analysed. Besides, endogenous antioxidant parameters like SOD, GSH, and catalase were also assessed. Lastly, the histopathological study of the beta cells in islets of the pancreas, glomerulus, and tubules of kidney and liver cells was conducted in all groups. The result shows significant reduction (p<0.001) of blood sugar in the naringin and glimepiride-treated group when compared with the control group (diabetes). Additionally, the combination of Naringin (100 mg/kg) and Glimepiride (0.1 mg/kg) significantly restores the creatinine levels and urine volumes, SGOT, SGPT, and ALP when compared to a single dose of administration. Further, the abnormal lipid profile levels (TC, LDL, TG, and HDL), and endogenous antioxidant enzymes (SOD, GSH, catalase) in diabetic control rats were restored to normal levels in a significant manner. The histopathological result reveals significant alterations, including hypertrophy of islets and mild degeneration, renal necrosis, and inflammation of hepatocytes. A synergistic effect of Naringin and glimepiride was observed during the estimation of various biochemical parameters like body weight, fasting blood sugar, creatinine, urine level, TG, total cholesterol, SGOT, SGPT, ALP, Insulin, HbA1c, antioxidant parameters like SOD, GSH, and catalase in STZ-induced diabetic rats. Further, the combination of therapy improves the protective effect of the pancreas, kidney, and liver, suggesting a potential antidiabetic effect.

Elevated blood pressure follows physiological body-water conservation

Background: Pre-clinical evidence suggests that blood pressure (BP) increase is part of an adaptive physiological body response designed to prevent under-hydration. This idea challenges established thinking that hypertension is caused by initial salt-driven over-hydration. We tested the hypothesis that this alternative view also holds true in humans. Methods: In a mechanistic study, we investigated the interrelation between daily Na+ and water intake, renal solute and water excretion, renal water conservation, and body Na+ balance with BP in 6 healthy men living in a controlled environment for 205 days. In an additional daily-life observational study we investigated the interrelation between BP and adaptive-physiological water and Na+ conservation in 108 Singaporeans. Results: In participants living under controlled conditions, BP increased when urine osmolality was high, and fluid intake or urine volume was low. This BP-increasing water conservation response was not caused by body Na+ retention. Similarly, participants living under daily-life conditions showed a BP-elevating adaptive body water conservation response with increased plasma solute concentration, increased plasma vasopressin levels, and reduced urine volume production due to reduced renal free-water excretion. Participants with higher BP relied on more urea and glucose solutes, but on less Na+ solutes, to maintain their hydration status. Participants with essential hypertension showed more pronounced adaptive-physiological water conservation. None of these hypertension-specific water conservation responses were accompanied by differences in 24-h Na+ excretion. Conclusions: BP increase in humans is part of a systemic body water conservation response that occurs largely independent of body Na+ balance. The Mars500 Salt and Water Homeostasis Project was realized by grant support from the German Federal Ministry for Economics and Technology/DLR Forschung unter Weltraumbedingungen (50WB1624-50WB2024) and the Interdisciplinary Centre for Clinical Research (IZKF Junior Research Group 2), Friedrich-Alexander-University of Erlangen-Nuremberg to JT. The food products were donated by APETITO, Coppenrath und Wiese, ENERVIT, HIPP, Katadyn, Kellogg, Molda, and Unilever. The Sodium Storage in Singaporeans Project was realized with grant support from Duke NUS Medical School (Duke-NUS-KBrFA/2019/0026) to JT. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Acute kidney injury causes subclinical renal and endothelial injury in female rats which predisposes to adverse outcomes of pregnancy

Clinical data report a 3-5-fold increase in adverse pregnancy outcomes, including preeclampsia and small for gestational age neonates, among women with a history of acute kidney injury (AKI) despite clinical recovery of renal function. We developed a rat model of pregnancy post-AKI: Sprague-Dawley (SD) rats undergo a bilateral renal-ischemia reperfusion and fully recover renal function as measured by creatinine clearance 30 days post-AKI. Rats are then mated and during pregnancy recovered AKI rats exhibit decreased creatinine clearance, increased uterine artery resistance, reduced plasma volume expansion, and decreased fetal growth compared to pregnant rats that received sham surgery. Healthy pregnancy demands robust renal and vascular adaptations. Whether subclinical renal and vascular injury persists following AKI in females, and whether this is exacerbated in pregnancy to drive the adverse pregnancy outcomes remains unknown. We tested the hypothesis that AKI results in subclinical renal and vascular injury that lingers into pregnancy. Female SD rats were randomized to 45-minute warm bilateral renal ischemia reperfusion or sham (N=6-8/grp) and renal and vascular injury assessments were made 30 days post-AKI/Sham (pre-pregnancy) or during pregnancy on gestational day 20 (GD20). Pre-pregnancy urine volume measured via metabolic cage was greater in post-AKI rats compared to sham (10±1 vs 21±2 ml/daily urine, p&lt;0.05). Urinary kidney injury marker-1 (KIM-1) measured via ELISA 30 days post-AKI/Sham was greater in pre-pregnant AKI rats compared to sham (9685±871 vs. 6399±198 pg/24 hrs urine, p&lt;0.05). Vascular function, measured via wire myography on 3rd order mesenteric arteries 30 days post-AKI/Sham, revealed decreased endothelial-dependent relaxation to acetylcholine (ACh) (concentration-response, 1 nM-10 μM, 2-way ANOVA, RM, *p&lt;0.05). GD20 urine volume (31±5 vs 19±2 ml/daily urine, p&lt;0.05) and KIM-1 levels (9125±673 vs 6380±297 pg/daily urine, p&lt;0.05) were elevated in post-AKI pregnant rats compared to sham pregnant rats. Mason Trichrome renal staining revealed greater glomerular fibrosis (0.93±0.08 vs 0.04±0.04, *p&lt;0.05) and tubular fibrosis (1.7±0.19 vs 0.0±0.0, *p&lt;0.05) in post-AKI pregnant rats vs. sham pregnant. Ultrastructural changes to the kidneys were evaluated via electron microscopy and further revealed extensive brush border loss, loss of mitochondrial structure and mitochondrial swelling in post-AKI pregnant rats compared to sham pregnant. Endothelial-dependent relaxation to ACh was also lower (2-way ANOVA, *p&lt;0.05), suggesting enhanced endothelial dysfunction in post-AKI pregnant rats vs. sham pregnant. Taken together, these data suggest that with a history of AKI, subclinical renal and vascular injury is present despite “recovery” of renal function using clinical definitions and may predispose to adverse pregnancy outcomes in pregnant women with a history of AKI. 1R01HL169576 4R00HL146948 1RO1DK134695 AHA967662. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Differential Role for the Clock Gene, BMAL1, on Kidney Function in Male versus Female Rats

Many activities of modern life, such as social visits with friends at night, long working hours, jet lag, and shift work cause circadian rhythm disturbances, which increase the risk of renal decline and eventual disease. Chronic kidney disease (CKD) is defined by decreases in glomerular filtration rate (GFR) which is higher during the daytime and lower at night in healthy individuals. Prior studies indicate that processes critical for maintaining blood pressure ( e.g. autoregulation) contribute to this time-of-day-dependence mediated by a molecular timekeeping mechanism known as the molecular circadian clock that resides in all tissues including the kidney. We hypothesized that loss of the molecular clock would impair normal kidney physiology through misalignment of functional rhythms with normal environmental patterns associated with day and night. We used a rat model of circadian disruption to interrogate our hypothesis. Male and female brain and muscle ARNT-like protein 1 knockout (BMAL1 KO) and littermate control (CON) rats aged 12-14 weeks underwent GFR measurements using FITC-labeled sinistrin clearance at two times of the day corresponding to the dark (active) and light (inactive) periods. Following GFR measurements, rats were placed in metabolic cages with food to record water intake and urine excretion over 12h active and inactive periods. Implantable telemeters were used for 24h measurement of systolic and diastolic blood pressure, locomotor activity and body temperature. Autoregulatory behavior was assessed using the isolated juxtamedullary nephron preparation to determine afferent arteriole diameter responses to changes in perfusion pressure. Diurnal measurements of GFR revealed that male BMAL1 KO rats had a significantly lower GFR in the active period as compared to CON males (1.87±0.37 vs 2.55±0.47 ml/min/100g; 2-way ANOVA, p&lt;0.05; n=8-9). As a result, there was no diurnal variation in the KO males as seen in the CON males (Δ GFR 0.63±0.24 vs 0.04±0.21 ml/min/100g/12h CON vs KO respectively) (Sidak post-hoc, p&lt;0.05; n=8-9) in parallel with a lack of diurnal variation in urine volume and Na excretion. Both male (n=8) and female (n=6-9) BMAL1 KO rats also displayed a significantly lower 24h mean arterial pressure (Males; 103±1 vs 107±1 mmHg, p&lt;0.05; Females; 110±1 vs 100±2 mmHg, p&lt;0.05) compared to CON with diurnal variation and autoregulatory reactivity preserved. Male BMAL1 KO rats consumed significantly more water compared to CON (n=5-9, 22.5±5.4 vs 14.7±4.0 mL/12h, p&lt;0.05) concomitant with increased urine excretion (n=5-9, 13.3±6 vs 4.2±0.8 mL/12h, p&lt;0.05) and reduced urine osmolality (n=5-7, 967±398 vs 2140±811 mmol/kg, p&lt;0.05) regardless of time of day. Taken together these data suggest that BMAL1 is necessary for maintaining renal functional rhythms and urine concentrating ability in a sex-dependent manner. R01 DK134562 P01 HL158500. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Pelvic Floor Function Exercises Based on the ERAS Concept on Lower Urinary Tract Symptoms after Radical Hysterectomy for Cervical Cancer: A Retrospective Cohort Study.

This study aimed to analyse the effect of pelvic floor function exercises based on the enhanced recovery after surgery (ERAS) concept on lower urinary tract symptoms after radical hysterectomy for cervical cancer. The retrospective study was conducted using clinical data of patients admitted to our hospital from January 2021 to December 2022 and underwent radical hysterectomy for cervical cancer. In accordance with the nursing method, the patients were divided into the routine group (conventional care) and the ERAS pelvic floor function exercise group, for which ERAS concept-based pelvic floor function exercises were carried out on the basis of the former group. The confounders between the two groups were matched by propensity score, and the scores of urination, pelvic floor muscle strength, lower urinary tract symptoms and quality of life (QoL) were compared between the two groups after matching. A total of 180 patients were included in the study, of whom 60 patients were identified after propensity score matching, consisting of 30 patients each in the ERAS and routine groups. The baseline characteristics of the two groups were balanced, and the difference was not statistically significant (p > 0.05). Compared with the routine group, the observation group showed significantly shorter first spontaneous urination time, greater first urination volume (p < 0.05), better pelvic floor muscle strength, considerably lower urinary tract symptoms and better QoL at discharge and 3 months after discharge (p < 0.05). Pelvic floor function exercises based on the ERAS concept can relieve lower urinary tract symptoms, accelerate urination and improve pelvic floor muscle strength and QoL after radical hysterectomy for cervical cancer.

Generation and characterization of collecting duct specific GPR56 knockout mice

GPR56 is a multifunctional adhesin G protein-coupled receptor involved in diverse biological processes, including neurodevelopment and disease, immune regulation, reproduction, hemostasis, and tumorigenesis. The role of GPR56 in the kidneys has been understudied. A recent study demonstrated that GPR56 in the glomerular endothelial cells promoted diabetic kidney disease progression via regulation of eNOS. Using RNAscope in situ hybridization (ISH) for GPR56 and aquaporin 2 (AQP2) followed by immunofluorescent labeling with NKCC2 (thick ascending limb, TAL marker), we detected GPR56 mRNA highly expressed in the collecting duct (both AQP2 positive principal cells and AQP2 negative intercalated cells) and TAL of the loop of Henle. In contrast, GPR56 mRNA is not detected in the proximal tubule or glomeruli. This expression pattern is further confirmed by quantitative RT-qPCR for GPR56 in microdissected inner medulla/inner stripe outer medulla and renal cortex. Of note, inner medulla/ inner stripe outer medulla is primarily composed of the collecting duct and the loop of Henle. GPR56 mRNA exhibited over a 6-fold higher expression levels in the inner medulla/inner stripe outer medulla compared to renal cortex, which is consistent with limited expression in the proximal tubule. To determine the physiological role of GPR56 in the collecting duct, we generated a collecting duct-specific GPR56 knockout (GPR56CD-KO) mouse model by crossing GPR56flox (Control, Con) with cadherin 16 Cre (Ksp-Cre) mice. The deletion of GPR56 in the collecting duct was confirmed by RNAscope ISH for GPR56 and AQP2 followed by fluorescent labeling with NKCC2. GPR56CD-KO mice were born at predicted Mendelian frequencies, appeared grossly indistinguishable from Con mice, and developed normally. For baseline phenotypic characterization, we found no differences in blood pH (7.21±0.01 vs 7.19±0.01, NS), blood HCO3− (17.4±0.5 vs 16.8±1.1 mmol/L, NS), blood Na+ (143±0 vs 144±0 mmol/L, NS), or blood K+ (4.3±0.1 vs 4.3±0.1 mmol/L, NS) between GPR56CD-KO (n=5, males) and Con mice (n=6, males). We also conducted metabolic cage experiments. No differences were observed for fluid intake (4.7±0.5 vs 4.5±0.2 mL/(day*30 g bodyweight), NS), urine volume (629±87 vs 662±108 mL/day, NS), urinary pH (5.75±0.03 vs 5.69±0.03, NS) or urine osmolality (2456±151 vs 2776±253 mOsm/kg, NS) between genotypes in baseline. After 24hr water deprivation, urine osmolality in both mice groups had significantly increased compared to that in baseline, however, no difference (Δ change: 558±82 vs 583±60 mOsm/kg, NS) was found between GPR56CD-KO and Con mice. In conclusion, we successfully generated collecting duct-specific GPR56 knockout mouse and found no defective urine concentrating ability in GPR56CD-KO mice. This mouse model will be useful to delineate the collecting duct-specific role of GPR56 for renal function, including acid-base regulation. We will also generate whole kidney GPR56 knockout mice to determine the isolated role of GPR56 in the loop of Henle compared to that in the collecting duct. This study is supported by the National Institute of Diabetes and Digestive and Kidney Diseases (4R00DK127215). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic kidney disease alters tryptophan metabolite concentrations in male and female Sprague Dawley rats

Kynurenine is the first stable metabolite of tryptophan degradation. An increased ratio of kynurenine (KYN) to tryptophan (TRP) has been implicated in many disease states including chronic kidney disease (CKD) in humans. We hypothesized that we would see a similar increase in KYN/TRP in a CKD model in male and female rats. We induced CKD with a 0.25% adenine diet for 15 weeks and then measured a variety of renal parameters. Serum and kidneys were collected at sacrifice. We found that GFR was better preserved in CKD female rats compared to males (0.232 ± 0.056 vs. 0.081 ± 0.019 ml/min/100g BW) but was decreased significantly compared to controls (0.739 ± 0.048 female, 0.635 ± 0.099 male). Urine volume was elevated significantly in CKD rats compared to controls (80.0 ± 6.9 ml/day male CKD, 72.5 ± 4.7 female CKD vs. 13.3 ± 1.1 male CTL and 22.0 ± 1.8 female CTL). However, male CKD rats consumed significantly more water than female CKD (104.1 ± 7.3 ml/day male vs. 81.0 ± 5.1 female), although water consumption was similar in controls in both sexes (30.9 ± 2.6 male and 30.1 ± 2.5 female). Weekly food consumption and body weight were similar between same sex groups. Both male and female rats showed increased KYN/TRP in CKD compared to controls (0.102 ± 0.010 in male and 0.105 ± 0.011 in female CKD vs. 0.049 ± 0.005 and 0.033 ± 0.002 CTL). Similarly, kynurenic acid was elevated significantly in both sexes in CKD (305.7 ± 76.7 nmol/L male and 669.2 ± 140.7 female) compared to controls (92.3 ± 17.7 and 118.1 ± 14.7) respectively. These data show that the adenine feeding model of CKD reproduces many of the characteristics of human disease including alterations in TRP metabolites. This model will allow study of TRP metabolites in CKD progression. This work was supported by Career Development Award IK2 BX004997 from the United States Department of Veteran Affairs, Biomedical Laboratory Research and Development Service. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluation of renal sodium handling in heart failure with preserved ejection fraction: A pilot study.

The pathophysiology behind sodium retention in heart failure with preserved ejection fraction (HFpEF) remains poorly understood. We hypothesized that patients with HFpEF have impaired natriuresis and diuresis in response to volume expansion and diuretic challenge, which is associated with renal hypo-responsiveness to endogenous natriuretic peptides. Nine HFpEF patients and five controls received saline infusion (0.25 mL/kg/min for 60 min) followed by intravenous furosemide (20 mg or home dose) 2 h after the infusion. Blood and urine samples were collected at baseline, 2 h after saline infusion, and 2 h after furosemide administration; urinary volumes were recorded. The urinary cyclic guanosine monophosphate (ucGMP)/plasma B-type NP (BNP) ratio was calculated as a measure of renal response to endogenous BNP. Wilcoxon rank-sum test was used to compare the groups. Compared to controls, HFpEF patients had reduced urine output (2480 vs.3541 mL; p = 0.028), lower urinary sodium excretion over 2 h after saline infusion (the percentage of infused sodium excreted 12% vs. 47%; p = 0.003), and a lower baseline ucGMP/plasma BNP ratio (0.7 vs. 7.3 (pmol/mL)/(mg/dL)/(pg/mL); p = 0.014). Patients with HFpEF had impaired natriuretic response to intravenous saline and furosemide administration and lower baseline ucGMP/plasma BNP ratios indicating renal hypo-responsiveness to NPs.

Sex-dependent polymorphism in urinary output is reversed upon deletion of exchange protein directly activated by cAMP (Epac)

It is well-described that there are notable sex-dependent differences in urinary production with females having a smaller volume and greater urinary concentrating ability. Apart from contribution of the androgenic inputs, the underlying signaling intermediates remain largely unexplored. We previously showed that exchange protein directly activated by cAMP (Epac) is a critical regulator of water-solute transport in the proximal tubule and collecting duct. Deletion of either Epac1 or Epac2 isoforms increases urinary output and Na+ excretion. Here, we used metabolic cage balance studies to test whether Epac signaling mediates sex-dependent differences in urinary production. We found that concomitant deletion of Epac1&amp;2 moderately increases 24h urinary volume by 38% (from 1.82+/-0.13 to 2.52+/-0.21 ml) in males, but drastically augment urinary production in females by 320% (from 1.39+/-0.10 to 4.45+/-0.37 ml). This was associated with only a mild though significant reduction in urinary osmolarity in males by 35%, whereas urine osmolarity was markedly decreased from 2511+/-5 to 977+/-60 mOsm in females. Consistently, plasma osmolarity was not different in EpacWT versus Epac1&amp;2−/− males, but became significantly more hypertonic in Epac1&amp;2−/− females. We further determine the functional consequences of impaired Epac cascade on fluid reabsorption in the proximal tubule and collecting duct in males and females. Deletion of Epac1 and Epac2 decreases NHE-3 expression in the proximal tubule in an additive manner. In addition, Na+/H+-dependent recovery after acidification was drastically reduced in freshly isolated split-opened proximal tubules from Epac1&amp;2−/− mice when compared to EpacWT. Interestingly, the reduction of NHE-3 expression was more pronounced in Epac1&amp;2−/− females (by 89%) than in males (by 59%). Immunofluorescence confocal images revealed much more diffuse intracellular distribution of AQP2 water channel in Epac1&amp;2−/− females when compared to males. Furthermore, osmotically-driven water influx was reduced in principal cells within split-opened collecting ducts of Epac1&amp;2−/− females but not males, when compared to respective EpacWT. In summary, our results reveal a substantially greater role of Epac signaling in renal water handling in females than in males. Interestingly, Epac1&amp;2 deletion leads to a reversed pattern of sexual dimorphism in urinary production with females excreting larger volumes of hypotonic urine than males. This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Urinary Bladder Dysfunction in a Novel Model of Neuroendocrine Stress

Chronic stress can lead to urinary bladder dysfunction and pain either through actions within the central nervous system or by mechanisms that are locally induced in the bladder. Prolonged upregulation of brain-derived neurotrophic factor (BDNF) in the paraventricular nucleus of the hypothalamus (PVN) has been shown to induce hypertension and chronically elevate activities of the sympathetic nervous system and hypothalamus-pituitary-adrenal axis. Taking advantage of this mechanism, we created a novel model of chronic neuroendocrine stress by subjecting male Sprague Dawley rats to bilateral PVN injections of AAV2 viral vectors expressing either BDNF or GFP (for control). We tested the hypothesis that model-induced chronic neuroendocrine stress would impair bladder function. Bladder activity was assessed 10 weeks post-injections by monitoring the number of urinary voids and average urinary void volume along with water intake over a 48-hour period. To further characterize changes in the urinary bladder, bladder weights were recorded, and in vitro bladder strip experiments were conducted 14 weeks after viral vector injections. BDNF overexpression in the hypothalamus led to significantly lower daily urine output even though water intake remained unaffected, suggesting that BDNF-treated animals showed a significantly higher non-urine-related fluid compared to GFP controls (daily urine output = GFP: 33.85±4.94, BDNF: 14.82±2.18, p &lt; 0.01. Interestingly, despite a lower total daily urine volume, BDNF-treated animals had a significantly higher number of urinary voids (GFP: 7.50±1.42, BDNF: 15.38±2.76; GFP vs. BDNF: p &lt; 0.001) and lower average void volume (GFP: 1.19±0.15, BDNF: 0.27±0.07; GFP vs. BDNF: p &lt; 0.01), thus emulating the overactive bladder phenotype, a common complication in humans with chronic stress. These findings were complemented by in vitro experiments where bladder strips from BDNF rats showed significantly higher contractility as tested with high K+ concentration and electric field stimulation. Moreover, Carbachol-induced stimulation of muscarinic receptors in BDNF bladder strips also trended towards higher contractility. However, urinary bladder weights were unaffected by BDNF overexpression. In summary, we demonstrated that prolonged hypothalamic BDNF overexpression, a model of chronic neuroendocrine stress, leads to significant alterations in bladder function such that BDNF-treated rats exhibited a higher number of urinary voids and lower average void volume compared to GFP controls, and bladder strip experiments suggest that enhanced smooth muscle contractility may contribute to this overactive bladder phenotype. These findings from our novel experimental model will help elucidate pathways through which neuroendocrine stress mechanisms contribute to the development of the overactive bladder syndrome. Funded by R01HL166464, R03AG072016 and R01DK125543. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Protective effect of equol intake on bladder dysfunction in a rat model of bladder outlet obstruction.

This study evaluates the impact of equol, a metabolite of soy isoflavone, on bladder dysfunction in rats with bladder outlet obstruction (BOO). In addition, we investigate its potential as a neuroprotective agent for the obstructed bladder and discuss its applicability in managing overactive bladder (OAB). Eighteen male Sprague-Dawley rats were divided into three groups (six rats per group) during the rearing period. The Sham and C-BOO groups received an equol-free diet, while the E-BOO group received equol supplementation (0.25 g/kg). At 8 weeks old, rats underwent BOO surgery, followed by continuous cystometry after 4 weeks of rearing. The urinary oxidative stress markers (8-hydroxy-2'-deoxyguanosine and malondialdehyde) were measured, and the bladder histology was analyzed using hematoxylin-eosin, Masson's trichrome, and immunohistochemical staining (neurofilament heavy chain for myelinated nerves, peripherin for unmyelinated nerves, and malondialdehyde). Equol reduced BOO-induced smooth muscle layer fibrosis, significantly prolonged the micturition interval (C-BOO: 193 s, E-BOO: 438 s) and increased the micturition volume (C-BOO: 0.54 mL, E-BOO: 1.02 mL) compared to the C-BOO group. Equol inhibited the increase in urinary and bladder tissue malondialdehyde levels. While the C-BOO group exhibited reduced peripherin alone positive nerve fibers within the smooth muscle layer, equol effectively attenuated this decline. Equol reduces lipid peroxidation and smooth muscle layer fibrosis in the bladder and exhibited neuroprotective effects on bladder nerves (peripheral nerves) and prevented the development of bladder dysfunction associated with BOO in rats. Consumption of equol is promising for the prevention of OAB associated with BOO.

Deletion of Piezo2 from renal Foxd1+ stromal progenitors and descendent cells results in abnormal mesangial development and sex-specific differences in kidney function

Piezo2 is a mechanically activated ion channel recently identified in glomerular mesangial cells and renin+ juxtaglomerular (JG) cells. Despite several studies which confirm this localization of Piezo2 in the kidney, the function of Piezo2 in these cells remains ambiguous. In the current study, we hypothesized that loss of Piezo2 in mesangial and JG cells would result in abnormal glomerular development during nephrogenesis and impaired salt and water balance in adult mice. To test this hypothesis, we generated mutant mice lacking Piezo2 in Foxd1+ stromal progenitors and their cell lineages, which include mesangial and JG cells. Kidney morphology was assessed by immunofluorescent staining and z-stack confocal microscopy during late nephrogenesis (post-natal day 0, P0) and following maturation of the nephron (P20) in wild-type (Piezo2fl/fl, n=3), heterozygous (Foxd1GC/+Piezo2fl/+, n=3), and mutant (Foxd1GC/+Piezo2fl/fl, n=3) mice. In adult male and female mice (n=2/genotype/sex), blood pressure was measured by tail cuff (CODA Systems) between 1-4pm following 3 days of acclimation. In a separate group of control and mutant male and female mice (8-10 weeks, n=3-5/group/sex), a 4-hour saline challenge (i.p. 10% body weight) was performed to assess diuresis and natriuresis. At P0, we found that deletion of Piezo2 from Foxd1+ stromal progenitors and their cell lineages resulted in the abnormal distribution of mesangial cells within glomeruli, such that the mesangial area appears compressed compared to control or heterozygous mice. This phenotype was exacerbated in mutant mice by P20. In adult mice, female mutants had an increase in daytime mean arterial pressure (~10mmHg, mean 79 vs 88) compared to female controls. Cumulative urine excretion (4 hours, percent injected) was decreased in females compared to males, regardless of genotype (p&lt;0.001). Further, female mutant mice had a delayed diuresis response compared to control (2 hour, mean 16% vs 28% cumulative urine volume). However by 4 hours following a saline bolus both groups were similar. Taken together, these data indicate that deletion of Piezo2 in Foxd1+ stromal progenitors results in impairments in mesangial cell development during nephrogenesis and alterations in water and salt balance in adult female mice. Understanding the sex-specific roles of Piezo2 in kidney development and physiology is critical to identify the role of mechanosensation on renal homeostasis. NIH R01DK121014 to LO. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Renal tubular (pro)renin receptor deletion does not protect against kidney injury in db/db mice

Background: The (pro)renin receptor (PRR) is a multifunctional protein implicated in blood pressure regulation and kidney fibrosis. Previous studies report enhanced PRR expression in non-diabetic and diabetic kidney disease. In this study, we investigated whether deletion of renal tubular PRR attenuates kidney injury in type 2 diabetes. Methods: Floxed PRR mice were bred with mice expressing Pax8 rtTA and LC1 transgenes and db/db mice (B6.BKS) to obtain renal tubular PRR knockout (KO)-db/db mice. Age matched non-diabetic floxed controls, db/db mice and PRRKO-db/db mice were studied at 16, 20, 26 and 30 weeks of age. To induce PRR deletion, PRRKO-db/db mice were treated with 2 mg/ml doxycycline for 12 days at 8-10 weeks of age. Only male mice were included in this study. Results: All mice survived until the end of the study (N=5-7 mice/group). Compared to controls, db/db mice and PRRKO-db/db mice had higher body weights despite similar food intake throughout the study (p&lt;0.001 by one-way ANOVA). PRRKO-db/db mice had higher urine volume and water intake compared to controls and db/db mice (p &lt;0.01 by ANOVA). Db/db mice had elevated non-fasting blood glucose levels (average: 472 mg/dl at 16 weeks, 292 mg/dl at 30 weeks) while PRR KO-db/db mice had modestly elevated blood glucose levels (average 255 mg/dl at 20 and 30 weeks) relative to controls (average: 150 mg/dl). Urinary albumin excretion was markedly elevated in PRRKO-db/db mice relative to db/db mice and controls throughout the study (950 ug/day vs db/db:145 ug/day, controls: 50 ug/day, p&lt;0.001). At 30 weeks, kidney histology by PAS stain showed minimal tubular injury, glomerulosclerosis or interstitial inflammation among all 3 groups. Interestingly, podocin staining by immunofluorescence was reduced in db/db mice but not PRR-KO db/db mice. Compared to control mice, db/db mice had similar KIM-1, NGAL and collagen-1 mRNA expression in kidney cortex and inner medulla. PRR KO db/db mice had increased cortical KIM-1, NGAL and collagen-I expression compared to control and db/db mice (p&lt;0.01 by ANOVA). Plasma sPRR levels were almost two-fold higher in diabetic mice relative to controls with no difference between db/db mice and PRR KO-db/db mice. Urinary sPRR levels were undetectable in controls and mildly elevated in db/db mice (7.6 ± 0.7 pg/day) and PRR KO-db/db mice (47.6 ± 22.3 pg/ml). No differences in plasma prorenin/renin concentration was noted among the 3 groups while urinary prorenin/renin excretion was higher in PRRKO-db/db mice. Conclusion: Renal tubular deletion of PRR does not protect against kidney injury in type 2 diabetes. It is possible that loss of PRR impairs baseline tubular function which is exacerbated by type 2 diabetes. American Diabetes Association. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Benchmarks for urine volume generation and phosphorus mass recovery in commercial and institutional buildings

Phosphorus (P) is a finite resource and necessary nutrient for agriculture. Urine contains a higher concentration of P than domestic wastewater, which can be recovered by source separation and treatment (hereafter urine diversion). Commercial and institutional (CI) buildings are a logical location for urine diversion since restrooms account for a substantial fraction of water use and wastewater generation. This study estimated the potential for P recovery from human urine and water savings from reduced flushing in CI buildings, and proposed an approach to identify building types and community layouts that are amenable to implementing urine diversion. The results showed that urine diversion is most advantageous in CI buildings with either high daily occupancy counts or times, such as hospitals, schools, office buildings, and airports. Per occupant P recovery benchmarks were estimated to be between 0.04–0.68 g/cap·d. Per building P recovery rates were estimated to be between 0.002–5.1 kg/d, and per building water savings were estimated to be between 3 and 23 % by volume. Recovered P in the form of phosphate fertilizer and potable water savings could accrue profits and cost reductions that could offset the capital costs of new urine diversion systems within 5 y of operation. Finally, urine diversion systems can be implemented at different levels of decentralization based on community layout and organizational structure, which will require socioeconomic and policy acceptance for wider adoption.