Renal Vasodilation Research Articles

CGS-21680 defers cisplatin-induced AKI-CKD transition in C57/BL6 mice

Acute kidney injury (AKI), with a high mortality and morbidity, is known as a risk factor for developing progressive chronic kidney disease (CKD). Targeting transition of AKI to CKD displays an excellent therapeutic potential. This study aims at investigating the role of CGS-21680, selective A2AR agonist, in deferring Cis-induced AKI-CKD transition. The AKI-CKD transition model was induced in C57/BL6 mice by repeated low doses of Cis (2.5 mg/kg i.p for 5 consecutive days in two cycles with a recovery phase of 16 days between two cycles). CGS-21680 was administered daily for 6 weeks (0.1 mg/kg, i.p). Urine, blood, and kidney were collected at three different time points to track the disease progression. CGS-21680 administration preserved kidney function and attenuated tubular damage as evidenced by hematoxylin-eosin (H&E) histopathology. CGS-21680 significantly restored oxidative status as reflected by reduced malondialdehyde (MDA) content and increased total antioxidant capacity (TAC). CGS-21680 showed anti-inflammatory effect as indicated by decreased TNF-α and iNOS. Additionally, CGS-21680 ameliorated endothelial dysfunction and enhanced renal vasodilation as evidenced by upregulation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) expression and down regulation of endothelin-1 (ET-1) and its receptor endothelin-A (ET-A) receptor expression. CGS-21680 also attenuated renal fibrosis as reflected by the reduction of percentage of fibrosis in Masson's trichome-stained renal sections and down regulation of transforming growth factor beta1 (TGF-β1) protein expression in IHC-stained renal sections. In conclusion, CGS-21680 could defer Cis-induced AKI-CKD transition via its vasodilatory, antioxidant, anti-inflammatory, and anti-fibrotic effects.

Sex Dependence in Control of Renal Haemodynamics and Excretion in Streptozotocin Diabetic Rats-Role of Adenosine System and Nitric Oxide.

Recently, we compared an interplay of the adenosine system and nitric oxide (NO) in the regulation of renal function between male normoglycaemic (NG) and streptozotocin-induced diabetic rats (DM). Considering the between-sex functional differences, e.g., in the NO status, we present similar studies performed in female rats. We examined if the theophylline effects (non-selective adenosine antagonist) in NG and DM females with or without active NO synthases differed from the earlier findings. In anaesthetised female Sprague Dawley rats, both NG and DM, untreated or after NO synthesis blockade with L-NAME, theophylline effects, on blood pressure, renal hemodynamics and excretion, and renal tissue NO were investigated. Renal artery blood flow (Transonic probe), cortical, outer-, and inner-medullary flows (laser-Doppler technique), and renal tissue NO signal (selective electrode) were measured. In contrast to males, in female NG and DM rats, theophylline induced renal vasodilation. In NO-deficient females, theophylline induced comparable renal vasodilatation, confirming the vasoconstrictor influence of the renal adenosine. In NG and DM females with intact NO synthesis, adenosine inhibition diminished kidney tissue NO, contrasting with an increase reported in males. Lowered baseline renal excretion in DM females suggested stimulation of renal tubular reabsorption due to the prevalence of antinatriuretic over natriuretic tubular action of adenosine receptors. An opposite inter-receptor balance pattern emerged previously from male studies. The study exposed between-sex functional differences in the interrelation of adenosine and NO in rats with normoglycaemia and streptozotocin diabetes. The findings also suggest that in diabetes mellitus, the abundance of individual receptor types can distinctly differ between females and males.

The renal vasodilation from β-adrenergic activation in vivo in rats is not driven by KV7 and BKCa channels

Aim: The underlying mechanisms behind β-adrenergic renal vasodilation is not clarified. Several classes of K+ channels are potentially activated, so we tested the hypothesis that voltage-sensitive KV7 and Ca2+-activated BKCa channels contribute to the decrease in renal vascular tone in vivo and in vitro. Methods: Changes in renal blood flow (RBF) during β-adrenergic stimulation was measured in isoflurane-anesthetized rats using an ultrasonic flow probe. The isometric tension of segmental arteries from normo- and hypertensive rats and segmental arteries from wild-type mice and mice lacking functional KV7.1 channels was examined in a wire-myograph. Results: The β-adrenergic agonist isoprenaline increased RBF significantly in vivo. Neither activation nor inhibition of KV7 or BKCa channels reduced the β-adrenergic RBF response. In segmental arteries from normo- and hypertensive rats, inhibition of KV7 channels significantly decreased the β-adrenergic vasorelaxation. However, inhibiting the BKCa channel was equally effective. The β-adrenergic vasorelaxation was not different between segmental arteries from wild-type mice and mice lacking a functional KV7.1 channel. As opposed to rats, inhibition of KV7 channels did not affect the murine β-adrenergic vasorelaxation. Conclusion: Although inhibition and activation of KV7 and BKCa channels significantly changed baseline RBF in vivo, none of the treatments affected the β-adrenergic vasodilation. In segmental arteries however, inhibition of KV7 and BKCa channels significantly reduced the β-adrenergic vasorelaxation indicating that the regulation of RBF in vivo is driven by several actors in order to maintain an adequate RBF. Our data stresses the importance of verifying data in intact animals. None. 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.

Diagnostic accuracy of venous system ultrasound for subtypes of acute kidney injury

BackgroundManagement of acute kidney injury (AKI) in the ED can be difficult due to uncertainty regarding the aetiology. This study investigated the diagnostic value of venous system ultrasound for determining...

Renal vascular control during normothermia and passive heat stress does not differ between healthy younger men and women.

Men are likely at greater risk for heat-induced acute kidney injury compared with women, possibly due to differences in vascular control. We tested the hypothesis that the renal vasoconstrictor and vasodilator responses will be greater in younger women compared with men during passive heat stress. Twenty-five healthy adults [12 women (early follicular phase) and 13 men] completed two experimental visits, heat stress or normothermic time-control, assigned in a block-randomized crossover design. During heat stress, participants wore a water-perfused suit perfused with 50°C water. Core temperature was increased by ∼0.8°C in the first hour before commencing a 2-min cold pressor test (CPT). Core temperature remained clamped and at 1-h post-CPT, subjects ingested a whey protein shake (1.2 g of protein/kg body wt), and measurements were taken pre-, 75 min, and 150 min post-protein. Beat-to-beat blood pressure (Penaz method) was measured and segmental artery vascular resistance (VR, Doppler ultrasound) was calculated as segmental artery blood velocity ÷ mean arterial pressure. CPT-induced increases in segmental artery VR did not differ between trials (trial effect: P = 0.142) nor between men (heat stress: 1.5 ± 1.0 mmHg/cm/s, normothermia: 1.4 ± 1.0 mmHg/cm/s) and women (heat stress: 1.4 ± 1.2 mmHg/cm/s, normothermia: 2.1 ± 1.1 mmHg/cm/s) (group effect: P = 0.429). Reductions in segmental artery VR following oral protein loading did not differ between trials (trial effect: P = 0.080) nor between men (heat stress: -0.6 ± 0.8 mmHg/cm/s, normothermia: -0.6 ± 0.6 mmHg/cm/s) and women (heat stress: -0.5 ± 0.5 mmHg/cm/s, normothermia: -1.1 ± 0.6 mmHg/cm/s) (group effect: P = 0.204). Renal vasoconstrictor responses to the cold pressor test and vasodilator responses following an oral protein load during heat stress or normothermia do not differ between younger men and younger women in the early follicular phase of the menstrual cycle.NEW & NOTEWORTHY The mechanisms underlying greater heat-induced acute kidney injury risk in men versus women remain unknown. This study examined renal vascular control, including both vasodilatory (oral protein load) and vasoconstrictor (cold presser test) responses, during normothermia and heat stress and compared these responses between men and women. The results indicated that in both conditions neither renal vasodilatory nor vasoconstrictor responses differ between younger men and younger women.

The renal vasodilatation from β-adrenergic activation in vivo in rats is not driven by KV7 and BKCa channels.

The mechanisms behind renal vasodilatation elicited by stimulation of β-adrenergic receptors are not clarified. As several classes of K channels are potentially activated, we tested the hypothesis that KV7 and BKCa channels contribute to the decreased renal vascular tone in vivo and in vitro. Changes in renal blood flow (RBF) during β-adrenergic stimulation were measured in anaesthetized rats using an ultrasonic flow probe. The isometric tension of segmental arteries from normo- and hypertensive rats and segmental arteries from wild-type mice and mice lacking functional KV7.1 channels was examined in a wire-myograph. The β-adrenergic agonist isoprenaline increased RBF significantly in vivo. Neither activation nor inhibition of KV7 and BKCa channels affected the β-adrenergic RBF response. In segmental arteries from normo- and hypertensive rats, inhibition of KV7 channels significantly decreased the β-adrenergic vasorelaxation. However, inhibiting BKCa channels was equally effective in reducing the β-adrenergic vasorelaxation. The β-adrenergic vasorelaxation was not different between segmental arteries from wild-type mice and mice lacking KV7.1 channels. As opposed to rats, inhibition of KV7 channels did not affect the murine β-adrenergic vasorelaxation. Although inhibition and activation of KV7 channels or BKCa channels significantly changed baseline RBF in vivo, none of the treatments affected β-adrenergic vasodilatation. In isolated segmental arteries, however, inhibition of KV7 and BKCa channels significantly reduced the β-adrenergic vasorelaxation, indicating that the regulation of RBF in vivo is driven by several actors in order to maintain an adequate RBF. Our data illustrates the challenge in extrapolating results from in vitro to in vivo conditions.

Angiotensin II-independent abnormal renal vascular reactivity during puromycin nephropathy.

Experimental glomerulonephritis results in hypertension that is sensitive to salt. Nevertheless, salt retention alone cannot explain the increase in blood pressure. Angiotensin antagonistic therapy reduces hypertension caused by puromycin amino nucleosides (PAN). We investigated the hypothesis that PAN modifies renal vascular reactivity through processes dependent on angiotensin. Long-Evans rats were given an intraperitoneal injection of either puromycin (150 mg/kg) or saline (controls). Group 1 was fed a normal sodium diet (NSD, n = 9). Group 2 was given 30 mg/L of quinapril (Q) in addition to NSD (NSD + Q; n = 6). Group 3 received a high sodium diet (HSD, n = 7), and Group 4 received HSD + Q (n = 7). Systolic blood pressure (SBP), plasma creatinine, proteinuria, and sodium balance were monitored for 12 days. On day 15, renal vascular reactivity was assessed by administering increasing doses of angiotensin II, acetylcholine (ACh), and sodium nitroprusside (SNP) directly into the renal artery. SBP progressively increased in all PAN groups. This increase in SBP was greater in the HSD groups and was not significantly altered by Q treatment. SBP increased by 22 ± 4% (NSD), 51 ± 5% (NSD + Q), 81 ± 10% (HSD), and 65 ± 8% (HSD + Q). The renal blood flow of PAN rats did not return to baseline despite their normal renal vasoconstrictor responses to angiotensin II. Additionally, they showed reduced renal vasodilator responses to SNP and Ach. The vasodilator responses to both vasodilators were surprisingly unaffected by the inhibition of the angiotensin-converting enzyme (ACE). Renal vasodilator responses to both endothelium-dependent and independent variables were reduced in early PAN-induced hypertension. We found that the angiotensin-mediated mechanism is not responsible for this altered renal vasoreactivity.

Diuretic, Natriuretic, And Ca2+-Sparing Effect Of The Alkaloid Boldine In Rats

Abstract Background Previous studies indicate the renal vasodilating effects of boldine, an alkaloid found in Peumus boldus. However, its potential to induce diuresis still needs to be studied. Methods Wistar rats were used and the urine volume was noted for 8 h and further studied. Results The acute treatment at 0.1 and 0.3 mg/kg of boldine showed a diuretic, natriuretic, and Ca2+-sparing effect in rats without changing the urinary elimination of K+and Cl-. When boldine was given in combination with hydrochlorothiazide, there was an increase in urinary volume compared to the vehicle group. However, this was not different from the treatments in its isolated form. Urine Ca2+values ​​remained low but were not enhanced by this association. The excretion of Na+and Cl- was significantly increased compared to the group that received only vehicle or boldine. On the other hand, although the association of amiloride plus boldine did not result in a diuretic effect, the increase in Na+and the reduction in K+excretion were significantly potentiated. Furthermore, in the presence of the non-selective muscarinic receptor antagonist atropine, boldine showed reduced capacity to increase urinary volume, maintaining the natriuretic and Ca2+-sparing effect, besides a very evident K+-sparing action. Similar results were obtained in the presence of the non-selective cyclooxygenase inhibitor indomethacin. Furthermore, boldine showed an ex vivo antiurolithiasis activity, reducing calcium oxalate’s precipitation and crystallization. Conclusions This study reveals the diuretic, natriuretic, Ca2+-sparing, and antiurolithiatic effects of boldine, an action possibly related to muscarinic receptor activation and prostanoid generation.

Abstract P124: Piezo1 Mediates Vasodilation Induced By Acute Hyperglycemia In Mouse Renal Arteries And Microvessels

Background: Acute hyperglycemia (HG) is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients. The role of renal vasculature in this context is not clear. We hypothesize that HG-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS activation. Methods: Vasoreactivity of isolated mouse mesenteric (MA) and renal interlobar (ILA) arteries were analyzed using wire myography and that of renal afferent (AA) and efferent (EA) arterioles, and vasa recta (VR) using microvascular perfusion. Immunofluorescence and western blot were used for molecular analyses of isolated mouse blood vessels as well HUVECs. Results: Pre-treatment with HG (44 mmol L -1 glucose; 4 h) increased acetylcholine (ACh)-induced relaxation in ILA and MA, which was prevented by eNOS inhibition using L-NAME. Hyperosmotic mannitol solution had a similar effect. HG induced an immediate, L-NAME-inhibitable dilation in AA, EA, and VR, whereby stronger dilation in AA compared to EA. HG also increased glomerular filtration rate in mice. In HUVECs, HG and the Piezo1 activator Yoda1 increased levels of Piezo1 protein, phosphorylated CaMKII (p-CaMKII), Akt, and p-eNOS. The HG-effect could be prevented by inhibiting Piezo1 using GsMTx4 and CaMKII using KN93. Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the HG-effect, while Yoda1 caused relaxation and dilation, respectively. Conclusion: Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute HG. This mechanism may contribute to the pathogenesis of renal damage by acute HG.

Evaluation of Renoprotective Effect of Lipoic Acid and Bosentan Against Diclofenac-Induced Acute Renal Failure

Acute renal failure also known as acute kidney injury (AKI) is a complex health condition related to significant morbidity and mortality. In hospitalized patients, around 19-33 percent of AKI episodes are linked to drug induced nephrotoxicity. Although considered safe, NSAIDs such as diclofenac have gained special attention over the past few years due to the potential risk of renal injury. The direct effect of diclofenac-induced renal injury depends on targeting the mitochondria in kidney tissue, and formation of reactive oxygen species (ROS) resulting in oxidative stress. Secondly, diclofenac inhibit renal prostaglandin production, limiting renal afferent arteriole vasodilation, increasing afferent resistance; thus decreasing the glomerular capillary pressure below normal values and glomerular filtration rate will decrease resulting in AKI. Alpha-Lipoic acid (ALA) has beneficial effects in prevention or relief of symptoms of oxidative stress- related diseases, as it acts as antioxidant and anti-inflammatory micronutrient. Bosentan is a competitive antagonist with dual endothelin-1 receptors, as renal vascular ET-1 system is upregulated under many pathophysiological situations. In present study, we investigated the effect of lipoic acid and bosentan in diclofenac induced acute renal failure in male rats.
 We observed that diclofenac increased serum levels of urea, creatinine, malondialdehyde, KIM-1, TGFβ1 and fibronectin significantly (p>0.05) in the induction group compared to control group. While, SOD significantly (p>0.05) reduced in the induction group compared to control group. Both of lipoic acid and bosentan alone didn’t significantly protect against diclofenac induced AKI. However, the combination group showed a significant protection against AKI. Pearson correlation analysis showed a significant positive correlation between (urea and KIM-1) and between (creatinine and KIM-1) (r2=0.792 and r2=0.677 respectively). Furthermore, there was a significant positive correlation between fibronectin and urea (r2= 0.498, p>0.01) and fibronectin and creatinine (r2=0.356, p>0.05). Interestingly, KIM-1 showed a significant positive correlation with fibronectin (r2=0.536, p>0.01).
 ROC curve test was performed for KIM-1 and fibronectin biomarkers. The AUC for KIM-1 was 0.986 and for fibronectin was 0.829. We concluded that combination therapy of lipoic acid and bosentan showed a significant protective effect against diclofenac-induced AKI. In addition, fibronectin could be a promising biomarker for detection and diagnosis of acute kidney injury.
 Key words: Diclofenac, oxidative stress, alpha- lipoic acid, endothelin-1, bosentan

Celery Ethanol Extract Prevents Renal Ischemia-Reperfusion Injury via Increasing Nitrite Oxide and Superoxide Dismutase

Background: Acute kidney injury (AKI) is one of the health problems. Kidney ischemia-reperfusion injury (IRI) contributes to pathological conditions of AKI. An imbalance between renal vasoconstriction and vasodilatation mediators was played a role in IRI and its chronic complications. Stress oxidative and inflammation were major pathomechanism of IRI. Administration of celery ethanol extract is one of the efforts to prevent kidney damage caused by IRI. This study aimed to investigate the time effect of celery ethanol extract administration on inhibition of kidney IRI. Methods: Twenty male Sprague Dawley rats with a weight range of 190-210 g were selected for the study. The rats were divided into five groups randomly: sham operation (SO, n=4) group, IRI group (ischemia-reperfusion injury, n=4), IRI+S7 (celery ethanol extract 1000 mg/kg BW 7 days orally+ischemia-reperfusion injury, n=4), IRI+S14 (celery ethanol extract 1000 mg/kg BW 14 days orally+ischemia-reperfusion injury, n=4), IRI+S28 (celery ethanol extract 1000 mg/kg BW 28 days orally+ischemia-reperfusion injury, n=4). Serum samples were collected for creatinine serum, NO, SOD, and TNF-α measurement. mRNA expression of ET-1 and ETAR was quantified using reverse transcriptase-PCR. Result: Serum creatinine, NO, and SOD level in rats with celery ethanol extract 1000 mg/kg BW for 7 and 14 days administration before IRI induction lower than IRI group (p<0.05) and increase in 28 days administration. Meanwhile, the TNF-α level, ET-1, and ETAR gen expression lower than the IRI group but not significantly different (p>0.05). Conclusion: Administration of celery ethanol extract 1000 mg/kg BW for 7 days and 14 days prevents renal ischemia-reperfusion injury via increasing NO and SOD. Administration more than 28 days is not recommended.

#5079 THE EVALUATION OF RENAL FUNCTIONAL RESERVE WITH ORAL PROTEIN LOAD OR ULTRASOUND TEST: A REAL-LIFE PERSPECTIVE

Abstract Background and Aims The RFR (renal functional reserve) is the difference between the stimulated glomerular filtration rate (GFR) and the baseline GFR. This difference can be expressed in absolute terms (mL/min) or relative terms (percentage of increment relative to the baseline GFR). This index makes it possible to highlight a subclinical renal functional deterioration when the laboratory values of creatinine are still within the normal range. Measurement of RFR by protein load (1 g/kg of oral protein) (RFR-T) is now considered the gold standard for RFR assessment. RFR measured with protein load (RFR-T) predicts the risk of acute kidney injury (AKI) or chronic kidney disease (CKD) in both healthy and diseased patients and is particularly useful in patients with apparently normal renal function before stress candidate for interventions at real risk of renal failure (kidney donors, cardiac surgery, bone marrow transplants). However, the protein load test has a long duration (about 5 hours), requires numerous blood and urine samples, and is challenging to use on a large scale. Recent studies have proposed another method based on the variation of the renal intraparenchymal resistance index (IRRIV-T). In this case, the stress to which the kidney is mechanical. That is a weight (saline bag, representing 10% of the body weight) placed on the abdomen of the supine patient, which induces maximal renal vasodilation. The sampling of the intraparenchymal resistance doppler indices before and after the weight application would correlate, in preliminary studies, with the RFR tested with the protein load. Thus, offering a fast and non-invasive method. Eventually, comparing these divergent diagnostic procedures can guide us in choosing the most cost-effective approach to gain deeper insight into renal health. (Fig. 1) Method Our cross-sectional study aimed to compare the classic protein loaded RFR test (RFR-T) with the new IRRIV ultrasound test (IRRIV-T). This real-life study includes a normal-renal function population of 42 patients. Anthropometric parameters and cardiovascular risk factors were evaluated, and blood and urinary tests were performed. The inclusion criteria were: (i) age greater than 18 years; (ii) eGFR CKD-EPI > 60 mL/min/1.73 m2. Exclusion criteria were: (i) non-steroidal inflammatory drugs (NSAIDs), (ii) ultrasound evidence of renal morphological changes or artery stenosis. Each patient underwent oral protein load testing (RFR-T) and an ultrasound test (IRRIV-T). Pearson's correlation index analyzed the comparison between the 2 tests. Results There was no statistically significant correlation between RFR-T and IRRIV-T in terms of the RFR either in absolute numbers (R = 0.14, p = 0.37) or in percentage values (R = 0.15, p = 0.33). (Fig. 2) Based on our experience, the IRRIV test proved unreliable in evaluating RFR compared with the gold standard (RFR-T). Therefore, not suitable to be used as a possible alternative to the oral protein load test. Conclusion Unlike previous studies, our survey is a real-life study. Many of our patients have pathologies or take drugs that could alter the hemodynamic and the renal vascular response, consequently changing the outcome of the IRRIV test. However, it is a real-life experience that aims to offer a practical point of view, bringing to light the possible limitations of the ultrasound test when applied to a standard evaluation population and not to a healthy or highly selected population as in the only three previous works published in the literature up to now. Our work is the first original real-life study in this field.

Piezo1 Mediates Vasodilation Induced by Acute Hyperglycemia in Mouse Renal Arteries and Microvessels.

Acute hyperglycemia is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients, whereby the role of renal vasculature remains unclear. We hypothesize that hyperglycemia-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS (endothelial NO synthase) activation. Vasoreactivity was analyzed using wire myography in isolated mouse mesenteric arteries and renal interlobar, and using microvascular perfusion in renal afferent arterioles and efferent arterioles, and vasa recta. Immunofluorescence and Western blot were used for molecular analyses of isolated mouse blood vessels and human umbilical vein endothelial cells. Pretreatment with hyperglycemia (44 mmol/L glucose; 4 hours) increased acetylcholine-induced relaxation in interlobar arteries and mesenteric arteries, which was prevented by eNOS inhibition using Nω-nitro-L-arginine methylester hydrochloride. Hyperosmotic mannitol solution had a similar effect. Hyperglycemia induced an immediate, Nω-nitro-L-arginine methylester hydrochloride-inhibitable dilation in afferent arterioles, efferent arterioles, and vasa recta, whereby stronger dilation in afferent arterioles compared to efferent arterioles. Hyperglycemia also increased glomerular filtration rate in mice. In human umbilical vein endothelial cells, hyperglycemia, and the Piezo1 activator Yoda-1 increased levels of Piezo1 protein, p-CaMKII (phosphorylated Ca2+/Calmodulin-dependent protein kinase type II), Akt, and p-eNOS (phosphorylated eNOS). The hyperglycemia effect could be prevented by inhibiting Piezo1 using GsMTx4 (Grammostola spatulata mechanotoxin 4) and CaMKII using KN93. Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the hyperglycemia -effect, while Yoda-1 caused relaxation and dilation, respectively. Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute hyperglycemia. This mechanism may contribute to the pathogenesis of renal damage by acute hyperglycemia.

Relaxin mechanistic effects on renal hemodynamics and natriuresis: a mathematical modeling approach

Relaxin (RLX) is a hormone that stimulates renal vasodilation during early pregnancy. Recombinant RLX may have potential as a treatment for heart failure and chronic kidney disease, but its application has been limited in part due to uncertainties about its mechanism of action, and particularly its effect on glomerular capillary hydrostatic pressure (P gc ) and fluid status. The objective of this study was to couple mathematical modeling with experimental observations of the renal hemodynamic and natriuretic response to RLX, in order to quantitatively describe the mechanistic effects of relaxin on the kidney, and to predict its effect on clinically difficult-to-measure variables such as P gc . Utilizing a previously developed mathematical model of kidney function and hemodynamics, we began by hypothesizing a minimum set of RLX mechanisms (afferent/efferent vasodilation), fitting the available hemodynamic/natriuretic response in two previously published rat studies (GFR, renal plasma flow (RPF), mean arterial pressure (MAP), sodium and water excretion), and adding additional RLX mechanisms to the model only when the minimal set could not explain available data. We found that changes in renal vascular resistances alone were sufficient to reproduce observed changes in RPF, but insufficient to explain other data features. Experimental studies reported much larger increases in sodium excretion relative to water excretion with RLX, and this effect could only be reproduced if an effect of RLX on the osmotic setpoint for vasopressin release was included in the model – a mechanism that has previously been reported in ovariectomized rats treated with RLX. A small effect of RLX on heart rate was necessary to produce observed changes in MAP.In addition, the single experimental study in which P gc has been measured with RLX reported a rise in GFR but fall in P gc , and this difference could not be explained mathematically by relative afferent/efferent dilation or by downstream shifting of the filtration equilibrium with increased RPF; it could only be reproduced mathematically if RLX was assumed to large positive effect on glomerular membrane permeability. However, the magnitude of this effect is difficult to justify physiologically. Thus, while the model can be forced to fit this limited data, further study is needed to understand whether and how RLX might have such large permeability effects.The fitted model was then able to make predictions consistent with observed renal responses in human subjects, and these effects were better predicted when the RLX effect on permeability was excluded, further suggesting that this effect may not be real. In these simulations, RLX had no net effect on P gc . In conclusion, while some uncertainty remains, this analysis suggests that RLX acts primarily by dilating the afferent and efferent arterioles and shifting the osmotic setpoint for vasopressin release. AstraZeneca and Eli Lilly This is the full abstract presented at the American Physiology Summit 2023 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.

Preeclamptic programming unevenly perturbs inflammatory and renal vasodilatory outcomes of endotoxemia in rat offspring: modulation by losartan and pioglitazone.

Introduction: Preeclampsia (PE) enhances the vulnerability of adult offspring to serious illnesses. The current study investigated whether preeclamptic fetal programming impacts hemodynamic and renal vasodilatory disturbances in endotoxic adult offspring and whether these interactions are influenced by antenatal therapy with pioglitazone and/or losartan. Methods: PE was induced by oral administration of L-NAME (50mg/kg/day) for the last 7 days of pregnancy. Adult offspring was treated with lipopolysaccharides (LPS, 5mg/kg) followed 4-h later by hemodynamic and renovascular studies. Results: Tail-cuff measurements showed that LPS decreased systolic blood pressure (SBP) in male, but not female, offspring of PE dams. Moreover, PE or LPS reduced vasodilations elicited by acetylcholine (ACh, 0.01-7.29nmol) or N-ethylcarboxamidoadenosine (NECA, 1.6-100nmol) in perfused kidneys of male rats only. The latter effects disappeared in LPS/PE preparations, suggesting a postconditioning action for LPS against renal manifestation of PE. Likewise, elevations caused by LPS in serum creatinine and inflammatory cytokines (TNFα and IL-1β) as well as in renal protein expression of monocyte chemoattractant protein-1 (MCP-1) and AT1 receptors were attenuated by the dual PE/LPS challenge. Gestational pioglitazone or losartan reversed the attenuated ACh/NECA vasodilations in male rats but failed to modify LPS hypotension or inflammation. The combined gestational pioglitazone/losartan therapy improved ACh/NECA vasodilations and eliminated the rises in serum IL-1β and renal MCP-1 and AT1 receptor expressions. Conclusion: Preeclamptic fetal programming of endotoxic hemodynamic and renal manifestations in adult offspring depends on animal sex and specific biological activity and are reprogrammed by antenatal pioglitazone/losartan therapy.

PS-B09-8: N-METHYL-D-ASPARTATE (NMDA) RECEPTORS INDUCE RENAL VASODILATION AND REGULATES BLOOD PRESSURE.

Introduction: N-methyl-D-aspartate receptors (NMDAr) are glutamate/glycine receptors expressed in the kidney. NMDAr induce renal vasodilation through an unknown mechanism. Connecting tubule-glomerular feedback (CNTGF) is a vasodilator feedback mechanism, initiated by ENaC in the connecting tubule producing afferent arteriole (AffA) vasodilatation and promoting sodium excretion. We hypothesized that NMDAr activation stimulate CNTGF and that the inhibition of NMDAr decrease CNTGF vasodilation inducing hypertension. Methods: We explore the presence of NMDAr receptors in mouse by transcriptome analysis of microdisseted tubules segments, total kidney western blot and immunofluorescence. We used mpkCCD cells (mouse principal cells) to explore the interaction between NMDAr and ENaC in PC using trasnwell current analysis and split-open tubule using patch clamp method. To determine the effect of NMDAr on CNTGF, we measured CNTGF-mediated AffA dilation in the presence or absence of NMDAr agonists glutamate and glycine with and without NMDAr antagonist (MK801), using a double-microperfusion method in rabbits, and in-vivo by micropunture technique in rats. To evaluate the effect of NMDAr on blood pressure (BP), we measure BP in NMDA 2C global knock out mice. BP was measure using tail cuff methods. To confirm the effect of NMDAr on BP we infused subcutaneously NMDAr inhibitor MK801 for 7 days in a gain of function β ENaC mutated allele mice on129/Sv background on normal salt diet. Results: NMDAr was found to be expressed in connecting tubule and co-localized with AQP2 and ENaC. In mpkCCD cells and open split tubules, NMDAr activation increase ENaC activity, while NMDAr inhibition decrease ENaC activity (p < 00.1). In-vitro, tubular microperfusion of NMDAr agonist increased AffA dilation (p < 0.001). NMDAr agonist-induced dilation was blunted with MK-801 (NMDAr blocker) and totally blocked with benzamil (CNTGF inhibitor). In vivo, NMDAr agonist increase CNTGF mediated vasodilation (P < 0.01). NMDAr 2C knock out mice showed high BP in comparison with wildtype (SBP 114.6 ± 7.3 vs 100.4 ± 2.2 mmHg, respectively, p = 0.01). In β ENaC mutated mice, the infusion of NMDAr inhibitor (Mk-801) induces hypertension (SBP 146 ± 8 mmHg) while the vehicle infused mice remained normotensives (110.7 ± 7.7 mmHg; p < 0.01). Conclusions: NMDAr in the connecting tubule increase renal vasodilation by activating CNTGF. The genetic ablation of NMDAr 2C or the pharmacological inhibition of NMDAr increase blood pressure. Future studies need to confirm the role of NMDAr in the pathogenesis of hypertension.

Refractory ascites after laparoscopic cholecystectomy: a case report

BackgroundLaparoscopic cholecystectomy is a common surgical option for gallstone disease with minimal trauma and rapid recovery. Ascites is a relatively uncommon complication after laparoscopic cholecystectomy and is more frequently observed in patients with preoperative abnormal liver function. However, patients without underlying liver disease develop refractory ascites after laparoscopic cholecystectomy are rare. We report a case of massive ascites caused by lymphatic injury after laparoscopic cholecystectomy.Case presentationA 63-year-old woman complained of abdominal discomfort and distension at the twelfth day after a laparoscopic cholecystectomy for gallbladder stones. Subsequently, the patient developed spontaneous bacterial peritonitis and a decreased output of urine. Abdominal computed tomography (CT) identified abdominal effusion. The patient received abdominocentesis and the volume of slightly turbid yellow ascites averaged 1500–2000 ml per day. The results of laboratory analysis of ascitic fluid showed the following: serum-ascites albumin-gradient (SAAG), 11–12 g/L; albumin, 11–14 g/L; triglycerides, 0.91 mmol/L. After the diuretic therapy, repeated large-volume paracentesis with albumin supplementation, administration of antibiotics and renal vasodilating medications, the patient’s symptoms did not relieve. Lymphoscintigraphy found a small amount of radioactive filling in the abdominal cavity. The patient finally received surgery with detection and ligation of the lymphatic leak. The ascites disappeared and the patient recovered well.ConclusionsFor patients with atypical characteristics of chylous ascites, lymphoscintigraphy could help to localize and qualify the diagnosis. Surgical treatment could be considered when conservative treatment fails.

Glomerular filtration rate reserve is reduced during mild passive heat stress in healthy young adults.

We tested the hypothesis that, compared with normothermia, the increase in glomerular filtration rate (GFR) after an oral protein load (defined as the GFR reserve) is attenuated during moderate passive heat stress in young healthy adults. Sixteen participants (5 women; 26 ± 2 yr) completed two experimental visits, heat stress or a normothermic time-control, assigned in a block-randomized crossover design. During the heat stress trial, core temperature was increased by 0.6°C in the first hour before commencing a 2-min cold pressor test (CPT) to assess renal vasoconstrictor responses. One-hour post-CPT, subjects ingested a whey protein shake (1.2 g of protein/kg body wt), and measurements were taken pre-, 75, and 150 min postprotein. Segmental artery vascular resistance was calculated as the quotient of Doppler ultrasound-derived segmental artery blood velocity and mean arterial pressure and provided an estimate of renal vascular tone. GFR was estimated from creatinine clearance. The increase in segmental artery vascular resistance during the CPT was attenuated during heat stress (end CPT: 5.6 ± 0.9 vs. 4.7 ± 1.1 mmHg/cm/s, P = 0.024). However, the reduction in segmental artery vascular resistance in response to an oral protein load did not differ between heat stress (at 150 min: 1.9 ± 0.4 mmHg/cm/s) and normothermia (at 150 min: 1.8 ± 0.5 mmHg/cm/s; P = 0.979). The peak increase in creatinine clearance postprotein, independent of time, was attenuated during heat stress (+26 ± 19 vs. +16 ± 20 mL/min, P = 0.013, n = 13). GFR reserve is diminished by mild passive heat stress. Moreover, renal vasoconstrictor responses are attenuated by mild passive heat stress, but renal vasodilator responses are maintained.

Profound Anatomical and Physiological Changes During Trimesters of Pregnancy. A Clinical Study

Aims and objectives: Current study was conducted from February 2022 to June 2022 in different Gynecological and medical institutes of Pakistan. The aims and objectives of study were to observe the anatomical and Physiological changes during Pregnancy in women. Materials and Methods: Sample size: 100 pregnant women were selected for this study and their age was in between 25-35 years. It was first pregnancy of all women how were considered in study. Parameters: Cardiac changes, renal vasculature, renal vasodilatation, renal plasma flow and glomerular filtration rate (GFR), respiratory changes, water metabolism, changes in alimentary tract, thyroid changes, blood glucose levels, systolic and diastolic blood pressure. Bio-statistical presentation: Raw data were presented by bio-statistically with the application of SPSS regression model 2020 in which compression was operated through mean standard deviation and significant (P<0.05) variations. Results: It was seen that during pregnancy the demand of oxygen showed a significant (P<0.05) increase (95.0±0.01), this is brought by a 20% rise in oxygen intake and 15% increase in metabolic rate and similarly Systolic blood pressure, Diastolic blood pressure, Random blood glucose levels, Intra-gastric pressure, Heart rate and BMI (152.0±0.03, 92.1±0.01, 156.0±0.01, 95.0±0.00, 9.0±0.02, 93.0±0.01, 35.01±0.01) in pregnant women also showed a significant (P<0.05) changes than the normal levels respectively. Conclusion: Pregnancy brings about physiological and anatomical changes that support the growing fetus and get the mother ready for labor and delivery. It's critical to distinguish between pathology associated with disease and typical physiological changes. Keywords: physiological, Anatomical, Trimester, vasodilatation, Intra-gastric pressure

Renal Vascular Resistance Does Not Differ Between Younger Men and Women

PurposeThe incidence of acute kidney injury is nearly two‐fold higher risk in men compared to women. A common cause of acute kidney injury is supply‐demand mismatch that is characterized by the presence of a comparatively low renal oxygen supply (i.e., blood flow) relative to tissue oxygen demand. Thus, it is possible that the control of renal blood flow differs between men and women. For instance, the vasodilator actions of estrogen may protect against excessive renal vasoconstriction or more readily promote renal vasodilation in pre‐menopausal women compared to men. However, whether renal vascular control, a function of both vasoconstrictor and vasodilator capacities, differs between men and women is unknown. Therefore, this study tested the hypotheses that (1) renal vasoconstriction during a sympathetic stimulus (i.e., the cold pressor test, CPT) will be greater in young healthy men compared to young healthy women, and (2) renal vasodilation following an oral protein load will be greater in women compared to men.MethodsHealthy, men (n=13, age 26 ± 3 years) and eumenorrheic women (n=12, age 23 ± 3 years, 4 ± 1 day of menstrual cycle) completed a 2‐min CPT after one hour of supine rest to assess renal vasoconstriction. A whey protein shake (1.2 g of protein/kg of body weight) was ingested 1‐h post‐CPT to assess renal vasodilation. Blood pressure (Penaz method) was measured continually. Renal segmental artery blood velocity (BV, Doppler ultrasound) was measured before and during the CPT (1‐ and 2‐min), and pre‐protein and 75‐ and 150‐min post‐protein. Segmental artery vascular resistance (VR) was calculated as mean arterial pressure (MAP) divided by segmental BV. Data are presented as mean ± SD.ResultsMAP increased in both men and women from pre‐CPT to 2 min (p<0.001), and the magnitude of increase did not differ between men (peak: +25 ± 13 mmHg) and women (peak: +23 ± 9 mmHg, p=0.667). Peak reductions in segmental BV (men: ‐1.3 ± 3.2 cm/s, women: ‐3.7 ± 2.9 cm/s, p=0.065) and increases in segmental VR (men: +1.5 ± 1.0 mmHg/cm/s, women: +2.1 ± 1.0 mmHg/cm/s, p=0.155) during the CPT did not differ between men and women. MAP did not differ between men and women pre‐protein or at 75‐min post‐protein (p>0.586) but was higher in men at 150‐min post‐protein (86 ± 7 mmHg vs. 78 ± 8 mmHg, p=0.042). Peak increases in segmental BV following protein ingestion were greater in women (+5.3 ± 2.2 cm/s) compared to men (+2.7 ± 2.4 cm/s, p=0.009). Similarly, peak reductions in segmental VR were greater in women (‐1.1 ± 0.6 mmHg/cm/s) compared to men (‐0.6 ± 0.6 mmHg/cm/s, p=0.030) following protein ingestion.ConclusionRenal vasoconstrictor responses to sympathetic stimulation do not appear to differ between healthy men and women. However, women displayed greater renal vasodilatory responses to an oral protein load. Therefore, renal vascular control differs between healthy men and women tested in the early follicular phase of the menstrual cycle. These findings may provide mechanistic insights in support of observations that acute kidney injury incidence differs between men and women.