Urinary Electrolyte Excretion Research Articles

Diurnal rhythms of urine volume and electrolyte excretion in healthy young men under differing intensities of daytime light exposure

In humans, most renal functions, including urine volume and electrolyte excretions, have a circadian rhythm. Light is a strong circadian entrainment factor and daytime-light exposure is known to affect the circadian rhythm of rectal temperature (RT). The effects of daytime-light exposure on the diurnal rhythm of urinary excretion have yet to be clarified. The aim of this study was to clarify whether and how daytime exposure to bright-light affects urinary excretions. Twenty-one healthy men (21–27 years old) participated in a 4-day study involving daytime (08:00–18:00 h) exposure to two light conditions, Dim (< 50 lx) and Bright (~ 2500 lx), in a random order. During the experiment, RT was measured continuously. Urine samples were collected every 3 ~ 4 h. Compared to the Dim condition, under the Bright condition, the RT nadir time was 45 min earlier (p = 0.017) and sodium (Na), chloride (Cl), and uric acid (UA) excretion and urine volumes were greater (all p < 0.001), from 11:00 h to 13:00 h without a difference in total daily urine volume. The present results suggest that daytime bright light exposure can induce a phase shift advance in urine volume and urinary Na, Cl, and UA excretion rhythms.

419-P: Correlation between 24-Hour Urinary Electrolyte and Urinary Albumin in Patients with Type 2 Diabetes

Objective: To explore the characteristics of 24-hour urinary electrolyte excretion in patients with type 2 diabetes mellitus (T2DM), and its correlation with urinary albumin and early renal injury. Methods: A total of 1475 T2DM and 265 nondiabetic patients (ND group) from 2018 to 2020 were enrolled. According to the urinary albumin excretion rate (UAER), T2DM patients were divided into normal albuminuria group (NA group): UAER &amp;lt; 30mg/24h; Microalbuminuria group (MA group): UAER 30~300 mg/24 h; massive albuminuria group (PR group): UAER &amp;gt; 300mg/24h. The characteristics of 24h urinary electrolyte excretion in different groups were observed and the correlation between 24h urinary electrolyte excretion and urinary albumin was analyzed. Results: We found that 24h urinary potassium, sodium, chlorine, phosphorus and magnesium in all subgroups of T2DM were higher than those in ND group (P &amp;lt; 0.001), 24h urinary calcium in ND group was higher than that in PR group (4.3±2.1 vs. 3.2±2.5, P &amp;lt; 0.001), but lower than that in NA group (4.3±2.1 vs. 4.7±2.8, P &amp;lt; 0.001). As urinary albumin increased, 24h urinary calcium of T2DM patients showed a decreasing trend while the other urinary electrolytes showed an increasing trend (P &amp;lt; 0.001). Urinary albumin was positively correlated with 24h urinary potassium, sodium, chlorine, phosphorus, magnesium (r=0.133~0.169, P &amp;lt; 0.001) and negatively correlated with 24h urinary calcium (r= -0.130, P &amp;lt; 0.001). Multiple linear regression showed that 24h urinary potassium was an independent influencing factor of urinary albumin (β = 0.178, P &amp;lt; 0.001). Conclusion: There is a difference in 24h urinary electrolyte excretion between T2DM and nondiabetic patients. The urinary electrolyte excretion of T2DM patients varies with urinary albumin. 24h urinary electrolyte excretion changes before the appearance of albuminuria, which may be an indicator of early renal injury. High urinary potassium may serve as a parameter to predict early diabetic nephropathy. Disclosure Y. Wang: None. M. Zhang: None. H. Li: None. S. Qu: None.

Plasma Renin Activity after Diuretic Treatment in Patients with Stable Heart Failure: With Special Reference to its Association with Electrolyte Chloride

A recent study reported an intimate association between urinary chloride (Cl) and plasma renin activity (PRA) in acute heart failure (HF) status, reflecting normal functioning of the ‘tubulo-glomerular feedback’ mechanism. Whether the ‘tubuloglomerular feedback’ mechanism functions normally in stable HF status, however, is unclear. This study examined whether the ‘tubulo-glomerular feedback’ mechanism functions normally under resolution of worsening HF after decongestive therapy. Data from 26 patients with acute HF and its recovery after decongestive therapy were analyzed. Clinical tests included measurement of peripheral blood tests, serum and spot urinary electrolytes, plasma neurohormones, and fractional urinary excretions of electrolytes. In a total of 26 patients, PRA increased after acute HF treatment (from 1.64±2.0 to 5.48±6.1 ng/ mL/h, p=0.002). Changes in the serum logPRA and urinary Cl concentration from worsening to its recovery tended to be inversely correlated (R2 =0.12, p=0.085) and logPRA and the serum Cl concentration at recovery were inversely correlated (R2 =0.23, p=0.01). When divided into 2 groups (n=13 in each) according to the median PRA, the group with greater PRA changes showed a larger decrease in the urinary Cl concentration (from 110±44 to 72.8±38, p=0.03). The group with higher PRA at recovery showed a lower serum Cl concentration than the group with lower PRA at recovery (102±6.5 vs 107±4.2 mEq/L, p=0.04). In conclusion, the association between PRA and the serum/urinary Cl concentration is blunted in stable HF under-decongestive therapy, possibly due to the physiologic status under full cardiovascular medication compared with that in acute HF status.

Empagliflozin ameliorates symptoms of diabetes and renal tubular dysfunction in a rat model of diabetes with enlarged kidney (DEK).

BackgroundSodium-glucose cotransporter 2 (SGLT2) inhibitors are widely used to reduce hyperglycemia. The present study investigated the effects of a SGLT2 inhibitor, empagliflozin, on hyperglycemia in a novel rat model of non-obesity type 2 diabetes with enlarged kidney (DEK).MethodsMale DEK rats with non-fasting blood glucose concentrations ≤300 mg/dl and >300 mg/dl were classified as nondiabetic and diabetic, respectively. Groups of nondiabetic (control) and diabetic (DM-cont) rats were fed standard chow for 12 weeks, whereas another group of diabetic (DM-empa) rats was fed standard chow containing empagliflozin (300 mg/kg/day) for 12 weeks. Blood glucose, body weight, glucose tolerance, food and water intake, urinary volume, plasma and urinary biochemical parameters, and bone mineral density were measured, and their kidneys and pancreas histologically analyzed.ResultsTreatment with empagliflozin reduced blood glucose concentration and food intake in diabetic rats, but inhibited loss of adeps renis and led to body weight gain. Empagliflozin attenuated polyuria and polydipsia but increased plasma concentrations of total cholesterol, sodium and total protein toward normal level. Empagliflozin also significantly reduced urinary excretion of proteins and electrolytes and restored bone mineral density and plasma concentrations of valine and isoleucine to normal levels. Moreover, dilation of renal tubules and kidney enlargement were not attenuated in the DM-empa group.ConclusionThe response of DEK rats to empagliflozin differed from that of other diabetic animal models, suggesting that DEK rats have unique characters for studying and evaluating the multiple biological effects of SGLT2 inhibitors. These findings also indicted that empagliflozin could ameliorate systemic metabolism and improve renal tubule function in diabetic condition.

The Role of Superoxide in Sex Differences in Angiotensin II‐induced Hypertensive and Natriuretic Responses in Mice with Proximal Tubule‐Specific Deletion of Mitochondrial Protein Sirtuin 3 in The Kidney

Sirtuin 3 (SIRT3), aNAD-dependent deacetylase, is a major mitochondrial protein in the matrix that is encoded by the SIRT3 gene. The key functions of SIRT3 in the mitochondria include anti-oxidative, anti-aging, anti-inflammation, and blood pressure-regulating effects by decreasing reactive oxygen species/superoxide production. However, the role of SIRT3 via superoxide in the proximal tubules (PT) of the kidney in angiotensin II-induced hypertensive or natriuretic responses remains poorly understood. To test our hypothesis, five groups of adult male and female wild-type (WT) and PT-SIRT3-/- mice were treated without (Control) or with Ang II (~0.65 mg/kg/day, i.p.) treated with 2% NaCl diet or tempol, a membrane-permeable radical scavenger and superoxide dismutase-mimetic (50 mg/kg/day, p.o.) for 2 weeks. Under basal conditions, systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) were significantly lower in adult male and female PT-SIRT3-/- mice than male and female wild-type mice (~13 ± 3 mmHg, P<0.01). Although there were no sex differences in male and female WT mice, SBP and MAP were significantly lower in female than male PT-SIRT3-/- mice (P<0.01). Urinary excretion of electrolytes including sodium (Na+), potassium (K+), chloride (Cl-), and lithium (Li+) were also significantly lower in female PT-SIRT3-/- mice (P<0.01). In response to Ang II infusion and 2% high salt treatment, SBP was increased similarly to 136 ± 7 mmHg in male and 135 ± 7 mmHg in female PT-SIRT3-/- mice (P<0.01). Urinary Na+, K+, Cl-, and Li+ excretion were all significantly increased in male and female PT-SIRT3-/- mice without significant sex differences in these responses to Ang II-induced hypertension. There were also no sex differences found in response to Ang II infusion alone. Tempol treatment alone had no significant effects on blood pressure and urinary electrolyte excretory responses compared with their basal levels. Interestingly, however, tempol treatment of Ang II-infused and 2% NaCl-fed male and female PT-SIRT3-/- mice revealed significant sex differences in these responses (P<0.01). SBP and MAP increased further in male (P<0.01), but not in female PT-SIRT3-/- mice (n.s.), whereas the natriuretic response was significantly greater in female PT-SIRT3-/- mice (P<0.01). Taken together, we concluded that SIRT3 in the mitochondria of the proximal tubules plays an important role in the development of ANG II-dependent hypertension, and that superoxide may be implicated in sex differences in Ang II-induced hypertensive and natriuretic responses in PT-SIRT3-/- mice.

Acute decrease of urine calcium by amiloride in healthy volunteers under high-sodium diet.

Amiloride is a competitive blocker of the epithelial sodium (Na) channel in the renal collecting duct. It is a less potent diuretic than thiazides or loop diuretics, but is often used in association with its potassium (K)-sparing profile. Whether amiloride has a hypocalciuric effect similar to thiazides remains unclear. Animal studies and experiments on cell lines suggested that amiloride increases calcium (Ca) reabsorption in the distal nephron, but human studies are scarce. We performed a post hoc analysis of a study with 48 healthy males (mean ± standard deviation age, 23.2 ± 3.9 years) who were assigned to a high-Na/low-K diet for 7 days before receiving 20 mg of amiloride orally. Urinary excretions of electrolytes were measured at 3 and 6 h afterwards; we calculated the relative changes in urinary excretion rates after amiloride administration. The high-Na/low-K diet led to an expected suppression of plasma renin and aldosterone. Amiloride showed a mild natriuretic effect associated with a decreased kaliuresis. Urinary Ca excretion dropped substantially (by 80%) 3 h after amiloride administration and remained low at the sixth hour. At the same time, fractional excretion of lithium decreased by a third, reflecting an increased proximal tubular reabsorption. During a high-Na/low-K diet, amiloride had a strong acute hypocalciuric effect, most probably mediated by increased proximal Ca reabsorption, even though a distal effect cannot be excluded. Further studies should establish if chronic amiloride or combined amiloride/thiazide treatment may decrease calciuria more efficiently and be useful in preventing kidney stones.

Clinical Significance of Spot Urinary Chloride Concentration Measurements in Patients with Acute Heart Failure: Investigation on the Basis of the ‘TubuloGlomerular Feedback’ Mechanism

Urinary chloride (Cl) is the key electrolyte for regulating renin secretion at the macula densa under the ‘tubulo-glomerular feedback’. Whether or not Cl filtrated into the urinary tubules actually associates with plasma renin activity (PRA) in clinical heart failure (HF) remains unclear. Data from 29 patients with acute worsening HF (48% men; 80.3±12 years) were analyzed. Blood and urine samples were immediately obtained before decongestive therapy after the patients rested in a supine position for 20-min. Clinical tests included peripheral blood tests, serum and spot urinary electrolytes, b-type natriuretic peptide (BNP), plasma neurohormones, and fractional urinary electrolyte excretion. In the 29 patients, urinary Cl concentrations inversely correlated with logarithmically transformed PRA (R2 =0.41, p=0.0002). The correlation was weaker in worsening chronic HF patients (R2 =0.32, p=0.01) compared with de novo HF patients (R2 =0.70, p=0.0026). Patients were divided into 2 groups according to the median urinary Cl concentration, a low group and a high group. Compared with the high group (100~184 mEq/L; n=14), the low group (4~95 mEq/L; n=15) exhibited more renal (serum creatinine; 1.45±0.63 vs 1.00±0.38 mg/d, p=0.029) and cardiac (log BNP; 2.99±0.3 vs 2.66±0.32 pg/mL, p=0.008 p=0.008) impairment, and higher PRA (3.42±4.7 vs 0.73±0.46 ng/mL/h, p=0.049), and lower fractional excretion of urinary Cl (1.34±1.3 vs 5.33±4.1%, p&lt;0.0001). The present study provides clinical data on the possible functioning of urinary Cl involved in the mechanism of ‘tubulo-glomerular feedback’, and thus advances our understanding of the clinical meanings of the significance of urinary Cl concentration measurement.

Prolonged Diuretic and Renoprotective Effects of a Xanthone Obtained from Garcinia achachairu Rusby in Normotensive and Hypertensive Rats.

The previous study showed that 1,5,8-trihydroxy-4′,5′-dimethyl-2H-pyrano(2,3 : 3,2)-4-(3-methylbut-2-enyl) xanthone (TDP) obtained from Garcinia achachairu Rusby (Clusiaceae) branches induces acute diuresis in normotensive (NTR) and spontaneously hypertensive rats (SHR) after 8 h of the experiment. In complementarity, the present study evaluated the prolonged diuretic and renoprotective effects of TDP in both NTR and SHR. The animals received, once a day, oral treatment with TDP (0.1 mg/kg), hydrochlorothiazide (10 mg/kg), or vehicle (VEH; 10 mL/kg). At the end of 7 days, the urine, blood, and kidney samples were collected for biochemical and histological analyzes. The urinary volume of both NTR and SHR after 7 days of treatment with the TDP was significantly increased, associated with augmented urinary electrolyte excretion levels. The treatments did not modify the urinary pH values nor the parameters analyzed in plasma (Na+, K+, Cl−, and Ca2+). Concerning the renal analyzes, when compared with the VEH-treated NTR group, while the activity of the enzymes catalase (CAT) and N-acetyl-β-D-glucosaminidase (NAG), as well as nitrite levels, were increased, the generation of lipid hydroperoxides and the activity of the enzyme myeloperoxidase (MPO) were unaltered. On the other hand, the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST) and the levels of reduced glutathione (GSH) in kidney homogenates of the SHR group were decreased. However, TDP augmented the levels of GSH and GST activities and reduced the levels of nitrite and the activities of CAT and MPO, when compared with VEH-treated only SHR. Besides, the treatment with TDP alleviated the morphological changes of the renal corpuscle region of SHR. Together, these results revealed the prolonged diuretic effect of TDP and their renal protective effect by improving the antioxidative capacity.

Clinical Significance of Spot Urinary Chloride Concentration Measurements in Patients with Acute Heart Failure: Investigation on the Basis of the ‘TubuloGlomerular Feedback’ Mechanism

Urinary chloride (Cl) is the key electrolyte for regulating renin secretion at the macula densa under the ‘tubulo-glomerular feedback’. Whether or not Cl filtrated into the urinary tubules actually associates with plasma renin activity (PRA) in clinical heart failure (HF) remains unclear. Data from 29 patients with acute worsening HF (48% men; 80.3±12 years) were analyzed. Blood and urine samples were immediately obtained before decongestive therapy after the patients rested in a supine position for 20-min. Clinical tests included peripheral blood tests, serum and spot urinary electrolytes, b-type natriuretic peptide (BNP), plasma neurohormones, and fractional urinary electrolyte excretion. In the 29 patients, urinary Cl concentrations inversely correlated with logarithmically transformed PRA (R2 =0.41, p=0.0002). The correlation was weaker in worsening chronic HF patients (R2 =0.32, p=0.01) compared with de novo HF patients (R2 =0.70, p=0.0026). Patients were divided into 2 groups according to the median urinary Cl concentration, a low group and a high group. Compared with the high group (100~184 mEq/L; n=14), the low group (4~95 mEq/L; n=15) exhibited more renal (serum creatinine; 1.45±0.63 vs 1.00±0.38 mg/d, p=0.029) and cardiac (log BNP; 2.99±0.3 vs 2.66±0.32 pg/mL, p=0.008 p=0.008) impairment, and higher PRA (3.42±4.7 vs 0.73±0.46 ng/mL/h, p=0.049), and lower fractional excretion of urinary Cl (1.34±1.3 vs 5.33±4.1%, p&lt;0.0001). The present study provides clinical data on the possible functioning of urinary Cl involved in the mechanism of ‘tubulo-glomerular feedback’, and thus advances our understanding of the clinical meanings of the significance of urinary Cl concentration measurement.

Benzamil-mediated urine alkalization is caused by the inhibition of H+-K+-ATPases.

Epithelial Na+ channel (ENaC) blockers elicit acute and substantial increases of urinary pH. The underlying mechanism remains to be understood. Here, we evaluated if benzamil-induced urine alkalization is mediated by an acute reduction in H+ secretion via renal H+-K+-ATPases (HKAs). Experiments were performed in vivo on HKA double-knockout and wild-type mice. Alterations in dietary K+ intake were used to change renal HKA and ENaC activity. The acute effects of benzamil (0.2 µg/g body wt, sufficient to block ENaC) on urine flow rate and urinary electrolyte and acid excretion were monitored in anesthetized, bladder-catheterized animals. We observed that benzamil acutely increased urinary pH (ΔpH: 0.33 ± 0.07) and reduced NH4+ and titratable acid excretion and that these effects were distinctly enhanced in animals fed a low-K+ diet (ΔpH: 0.74 ± 0.12), a condition when ENaC activity is low. In contrast, benzamil did not affect urine acid excretion in animals kept on a high-K+ diet (i.e., during high ENaC activity). Thus, urine alkalization appeared completely uncoupled from ENaC function. The absence of benzamil-induced urinary alkalization in HKA double-knockout mice confirmed the direct involvement of these enzymes. The inhibitory effect of benzamil was also shown in vitro for the pig α1-isoform of HKA. These results suggest a revised explanation of the benzamil effect on renal acid-base excretion. Considering the conditions used here, we suggest that it is caused by a direct inhibition of HKAs in the collecting duct and not by inhibition of the ENaC function.NEW & NOTEWORTHY Bolus application of epithelial Na+ channel (EnaC) blockers causes marked and acute increases of urine pH. Here, we provide evidence that the underlying mechanism involves direct inhibition of the H+-K+ pump in the collecting duct. This could provide a fundamental revision of the previously assumed mechanism that suggested a key role of ENaC inhibition in this response.

English

The present research was planned tostudy the pharmacodynamic effects and mechanisms of terpenoids composition in Alisma orientale. In vivo test, the rat edema model was established with setting up the blank control group, the positive control furosemide group and high-dose, medium-dose and low-dose terpenoids groups. Collected rat urine after administration and detected the biochemical indexes of rat urine. Detected the expression of medullary aquaporin 2 (AQP-2) in the rat kidney by Western Blot and immunohistochemistry and detected the expression of AQP-2 mRNA by polymerase chain reaction (PCR). In vitrotest, using human tubular epithelial cell HK-2 model, the activity of HK-2 cells was determined with MTT colorimetric assay, the expression of AQP-2 protein in HK-2 cells was detected by Western Blot, the expression of AQP-2 mRNA was detected by RT-PCR, and IHC wasused to detect the relative expression of AQP-2. In vivotest showed that terpenoids composition in alisma can increase urine volume, promote electrolyte excretion in urine and decrease the expression of AQP-2 in rat kidney. Results in vitrotest showed that terpenoids composition cannot inhibit cells survival obviously but reduce the relative expression of AQP-2. Conclusively, terpenoids composition in alisma inhibited the expression of AQP-2, having diuretic effect.© 2021 Friends Science Publishers

Tolerability, Pharmacokinetic, and Pharmacodynamic Profiles of Henagliflozin, a Novel Selective Inhibitor of Sodium-Glucose Cotransporter 2, in Healthy Subjects Following Single- and Multiple-dose Administration

BackgroundHenagliflozin, a novel selective inhibitor of sodium–glucose cotransporter 2, is under development as a treatment for type 2 diabetes mellitus. PurposeTo evaluate the tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) profiles of henagliflozin in healthy Chinese volunteers. MethodsTwo clinical studies were conducted. One was a single ascending dose (SAD) study (2.5–200 mg) involving 80 healthy subjects, and the other was a multiple ascending dose (MAD) study (1.25–100 mg for 10 days) involving 48 healthy subjects. The tolerability, PK profiles of henagliflozin and its main metabolites, and the urinary glucose excretion over 24 h were characterized in these 2 studies. FindingsNo serious adverse events were observed in the healthy subjects after single- and multiple-dose oral administration of henagliflozin, suggesting that this drug was well tolerated. Henagliflozin was rapidly absorbed, with a Tmax of 1.5–3 h, and then eliminated from plasma with a half-life of 11–15 h. It was not accumulated following once-daily oral administration. Plasma exposure of henagliflozin exhibited dose-proportional PK properties over the dose ranges of 2.5–200 mg (SAD) and 1.25–100 mg (MAD). The excretion of henagliflozin in urine was found to be very low, with 3.00%–5.13% of the dose. The glucuronide metabolites M5-1, M5-2 and M5-3 were the main metabolites detected in plasma samples, which accounted for up to 54.3%, 19.8%, and 27.5%, respectively, of the parent drug at steady state. Both the SAD and MAD studies demonstrated that the urinary glucose excretion over 24 h was dose-dependently increased and displayed saturation kinetics at >25 mg. No significant changes in the levels of serum glucose and urine electrolytes were found following a single or multiple doses of henagliflozin administration. ImplicationsHenagliflozin was well tolerated and showed predictable PK/PD profiles in these healthy subjects. Henagliflozin did not affect blood glucose level or urinary electrolyte excretion. It is best characterized for once-daily administration with a maximum dose of 25 mg. ChinaDrugTrials.org.cn identifiers: CTR20131986 and CTR20140132.

Evaluation of the Diuretic Activity of the Aqueous and 80% Methanol Extracts of Ficus sur Forssk (Moraceae) Leaves in Saline-loaded Rats.

BackgroundAlthough investigations on different pharmacological activities of the experimental plant, Ficus sur have been conducted, its folklore use for diuresis has not yet been validated. The current study, therefore, focused on the diuretic activity of aqueous and 80% methanol extracts of F. sur Forssk. leaves in rats.MethodsRats were randomly assigned into eight groups each consisting of six rats. Test groups received either 100 mg/kg, 200 mg/kg, or 400 mg/kg of aqueous or 80% methanol leaves extract. The negative control group and positive control were treated with 2 mL/100 g of distilled water and furosemide (10 mg/kg), respectively. Thereafter urine volume was recorded every hour until the end of the fifth hour, and cumulative urine volume of each rat was measured. Then, diuretic activity, diuretic index, saliuretic index, natriuretic index and carbonic anhydrase inhibition index in each group were calculated, and results were compared among the groups.ResultsThe middle (200 mg/kg) and the highest (400 mg/kg) doses of both extracts significantly increased diuresis at the fifth hour (p<0.001) compared to the negative control, although the diuretic activity was less than that of the positive control. Regarding electrolyte excretion, all dose levels of both extracts showed significant natriuresis (p<0.001) and chloriuresis (p<0.01) compared to the negative control. Aqueous extract displayed more significant diuretic effect than 80% methanol extract. The aqueous and 80% methanol extracts produced alkaline urine.ConclusionThe crude leaves extracts of F. sur increased urinary excretion and concentration of urinary electrolytes in a dose-dependent manner. These findings are in agreement with the traditional claim for use of F. sur as diuretic agent.

Diuretic Effect and Metabolomics Analysis of Crude and Salt-Processed Plantaginis Semen.

Plantaginis Semen (PS) is well recognized in traditional Chinese medicine (TCM) and health products. Crude PS (CPS) and salt-processed CPS (SPS) are the two most commonly used decoction pieces of PS, and are included in the 2020 edition of Chinese Pharmacopoeia. Although they all have multiple effects, the mechanisms for treating diseases are different and remain unclear, the processing mechanism of SPS is also indeterminate, which hinders their clinical application to a certain extent. In order to solve these problems and further develop PS in the clinical application. Here, we used saline-loaded model rats for experiments, and utilized an integrated approach consisting of pharmacological methods and metabolomics, which could assess the diuretic impact of CPS and SPS ethanol extracts on saline-loaded rats and elucidate the underlying mechanism. The results showed that CPS and SPS both produced increased urine volume excretion and urine electrolyte excretion, but the levels of aldosterone (ALD) and aquaporin 2 (AQP2) were decreased. And 30 differential metabolites such as linoleic acid, lysoPC(O-18:0), sphingosine-1-phosphate, lysoPC(18:0) were found, mainly involving three metabolic pathways. In conclusion, CPS and SPS both have a diuretic effect, and that of SPS is better. This work investigated the possible diuretic mechanisms of CPS and SPS which may also be the mechanism of PS for anti-hypertension. In addition, a holistic approach provided novel and helpful insights into the underlying processing mechanisms of TCM.

Circadian variation in renal blood flow and kidney function in healthy volunteers monitored with noninvasive magnetic resonance imaging.

Circadian regulation of kidney function is involved in maintaining whole body homeostasis, and dysfunctional circadian rhythm can potentially be involved in disease development. Magnetic resonance imaging (MRI) provides reliable and reproducible repetitive estimates of kidney function noninvasively without the risk of adverse events associated with contrast agents and ionizing radiation. The purpose of this study was to estimate circadian variations in kidney function in healthy human subjects with MRI and to relate the findings to urinary excretions of electrolytes and markers of kidney function. Phase-contrast imaging, arterial spin labeling, and blood oxygen level-dependent transverse relaxation rate (R2*) mapping were used to assess total renal blood flow and regional perfusion as well as intrarenal oxygenation in eight female and eight male healthy volunteers every fourth hour during a 24-h period. Parallel with MRI scans, standard urinary and plasma parameters were quantified. Significant circadian variations of total renal blood flow were found over 24 h, with increasing flow from noon to midnight and decreasing flow during the night. In contrast, no circadian variation in intrarenal oxygenation was detected. Urinary excretions of electrolytes, osmotically active particles, creatinine, and urea all displayed circadian variations, peaking during the afternoon and evening hours. In conclusion, total renal blood flow and kidney function, as estimated from excretion of electrolytes and waste products, display profound circadian variations, whereas intrarenal oxygenation displays significantly less circadian variation.

Postnatal Deletion of Bmal1 in Mice Protects Against Obstructive Renal Fibrosis Via Suppressing Gli2 Transcription

Background: Circadian clock is involved in regulating most renal physiological functions, including water and electrolyte balance and blood pressure homeostasis. However, the role of circadian clock in renal pathophysiology remains largely unknown. Methods: The inducible postnatal Bmal1 knockout mice (iKO) were used in the study. The diurnal oscillation of blood pressure and urinary water and electrolyte excretion was compared between iKO and controls. Unilateral ureteral obstruction (UUO) was performed to induce renal fibrosis. ChIP, luciferase reporter assay, and the in vitro cell culture experiments were used to elucidate the transcriptional activation of Bmal1 on Gli2. Findings: The iKO mice exhibit increased urinary volume and electrolyte excretion but abolished diurnal variation. Upon UUO, the iKO mice displayed significantly attenuated tubulointerstitial fibrosis and decreased expression of the hedgehog pathway transcriptional effectors Gli1 and Gli2. ChIP and luciferase reporter assays revealed that BMAL1 bound to the promoter of and activate the transcription of Gli2, but not Gli1, suggesting that the involvement of Bmal1 in renal fibrosis was possibly mediated via Gli2-dependent mechanisms. Furthermore, treatment with TGF-β increased Bmal1 in cultured murine proximal tubular cells, and knockdown of Bmal1 abolished, while overexpression of Bmal1 increased, Gli2 and the expression of fibrosis related genes. Interpretation: Our results revealed a prominent role of the circadian clock in renal fibrosis. Moreover, we identified Gli2 as a novel target of Bmal1, which may mediate the adverse effect of Bmal1 in obstructive nephropathy.

Abstract P040: Pressure Natriuresis In Female Sprague Dawley Rats: Characteristics And Mechanisms

Raising blood pressure stimulates pressure natriuresis (P-Nat). In males (M) Sprague Dawley rats (SDR), Na + reabsorption (T Na ) is acutely reduced by retraction of proximal tubule (PT) NHE3 to microvillar base and NaPi2 internalization. In females (F), at baseline PT NHE3 is already at microvillar base and NaPi2 is less abundant than in M. We AIM to determine characteristics and mechanisms of P-Nat in F (vs M) rats. Methods: Inactin anesthetized F and M SDR (n=5/group) were provoked by vasoconstriction (or sham). Mean arterial pressure (MAP) was recorded via carotid artery, urine collected via bladder, Na + transporters’ abundance assessed via immunoblot and localization by immunohistochemistry. Results (Fig 1A): Baseline MAP (mmHg) was lower in F vs. M (91 ± 5 vs.105 ± 3, P =0.04) while urine volume (UV) and electrolyte excretion (UNaV, UKV) were similar. After celiac and mesenteric bed constriction, MAP rose to 128 ± 3 mmHg in both sexes; UNaV, UV and C Na increased 12 to 15-fold in F (all P &lt;0.01) vs 6-fold in M ( P &gt;0.08). Constriction of abdominal aorta further raised UNaV in F with less impact in M. Na + transporters . In F, NHE3 remained at PT microvillar base and NaPi2 was internalized with vasoconstriction. NHE3P (indicating inactivation) abundance increased 29% in F, P =0.058. Lithium clearance, measure of volume flow leaving early nephron, increased 9-fold in F ( P =0.02) vs. 5-fold in M ( P =0.07). F mTAL NHE3, NKCC2p, and SPAKp (co-transporter kinase) abundances were 22, 24, and 43% lower vs shams ( ANOVA P &lt;0.0001). Summary: F vs M SDR exhibit more robust P-Nat associated with less T Na in early nephron and reductions in PT-mTAL Na + transporters, consistent with higher UNaV at any given BP (Fig 1B).

Urinary excretion of electrolytes and their correlation with clinical parameters in chronic kidney disease

Introduction: With the increasing incidence of chronic renal disease on a global scale, it is important to document the chemical abnormalities that not only indicate deteriorating renal function, but also aggravate the clinical picture by causing sustained electrolyte imbalance, ultimately contributing to End Stage Renal Disease (ESRD).&#x0D; Objective: To investigate 24-hr urinary electrolytes excretion of non-dialysis patients presenting with history of chronic kidney disease (CKD) and correlate the biochemical abnormalities with clinical parameters.&#x0D; Materials &amp; Methods: A total of 100 patients with CKD were included in a private clinic setup from February 2017 to December 2019 to retrospectively analyze the relationship of 24-hr urinary electrolytes with clinical indicators in these subjects. Besides demographic data, biochemical indices of concern were obtained through standard laboratory techniques. The patients were then divided on the basis of results into four quartile groups. Descriptive data analysis was done through SPSS 22.0.&#x0D; Results: Nephropathic patients had low eGFR, albumin, hemoglobin, blood calcium as well as 24-hr urine calcium and had high body mass index (BMI), systolic blood pressure, diastolic blood pressure, blood creatinine, blood sodium and 24-hr urine sodium. According to quartiles of 24-hr urinary sodium; in the Q4 group, 24-hr urine protein, 24-hr urine potassium and 24-hr urine calcium were the highest while according to quartile of 24-hr urinary potassium; the Q3 group had the highest 24-hr urine protein. According to quartile of urinary calcium, Q4 group blood calcium, 24-hr urine sodium and 24-hr urine potassium was high. The results revealed a positive correlation of 24-hr urinary sodium and potassium with 24-hr urine protein and a negative correlation of 24⁃hr urinary calcium with 24-hr urine protein.&#x0D; Conclusion: The levels of urinary electrolytes in patients with CKD are associated with urinary protein. It is, therefore, recommended that the above-mentioned disease be treated in these patients for their proper management.&#x0D; Keywords: Urine Chemistry; Proteinuria; Renal Insufficiency, Chronic.

Pharmacokinetics of magnesium and its effects on clinical variables following experimentally induced hypermagnesemia.

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO4 ) to healthy horses. MgSO4 is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO4 at 60mg/kg of body weight over 5min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg2+ ). Objective data were analyzed using the Wilcoxon rank-sum test with p<.05 used as a determination for significance. Plasma concentrations of Mg2+ increased nearly fivefold, ionized calcium (Ca2+ ) decreased by nearly 10%, and the Ca2+ to Mg2+ ratio declined more than 3.5-fold and remained different than baseline until 24hr (p<.05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca2+ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO4 .

586-P: Characteristics of 24-Hour Urinary Electrolyte Excretion and Its Correlation with Renal Function in Type 2 Diabetics

Objective: There are few studies on the characteristics of 24-hour urinary electrolyte excretion in patients with type 2 diabetes mellitus (T2DM),and it is unclear whether the level of 24-hour urinary electrolyte excretion is related to poor renal prognosis.This study aimed to explore associations between 24-hour urinary electrolyte excretion and renal function in T2DM patients. Methods: A total of 479 patients with T2DM in our hospital from 2018 to 2019 were enrolled. According to the estimated glomerular filtration rate (eGFR), patients were divided into normal group(eGFR≥90 mL/min/1.73m`2,n=317)and abnormal group(eGFR&amp;lt;90 mL/min/1.73m`2,n=162). The correlation between 24-hour urinary electrolyte excretion and eGFR in T2DM patients was analyzed. In addition, the 24-hour urine electrolyte excretion was compared with gender, diabetic duration, and HbA1c. Results: The levels of 24-hour urinary potassium, sodium and chlorine excretion in abnormal group were higher than normal group, the levels of calcium and phosphorus excretion were lower. Therein, levels of sodium(P=0.037) and calcium (P&amp;lt;0.001) had significant difference. The levels of 24-hour urinary potassium, sodium, chloride, calcium and phosphorus excretion in the male group were higher than female group, among which potassium (P&amp;lt;0.001), sodium (P=0.001), chloride (P=0.002), and phosphorus (P&amp;lt;0.001) were statistically significant. In addition, duration of disease and HbAlc was not related to 24-hour Urinary Electrolyte Excretion. Conclusion:There is a certain correlation between 24-hour urinary electrolyte excretion in T2DM and renal function. With the increase of 24-hour urinary sodium excretion and decrease of urinary calcium excretion, eGFR decreased, which was related to gender. Therefore, in patients with T2DM of the same gender, 24-hour urinary sodium and calcium excretion may be useful metabolic parameters for predicting poor renal prognosis, which needs further study. Disclosure Y. Wang: None. N. Li: None. L. Bu: None. H. Sun: None. B. Zhu: None. H. Li: None. S. Qu: None. Funding National Key Research and Development Program of China (2018YFC1314100); National Natural Science Foundation of China (81970677)