Fractional electrolyte excretion and osmolality in the early diagnosis of acute kidney injury in cats with urethral obstruction

Acute Kidney Injury (AKI) can be defined as a spectrum of diseases associated with a sudden onset of a renal failure status, the feline patient has azotemia, the disorder in fractional electrolyte excretion (FE), and shedding of epithelial cells from renal tubular segments observed in the urinary sediment. Thus, the objective of the present study was to evaluate the FE, plasma and urinary osmolality, and urinary specific gravity (USG) in cats that spontaneously developed AKI due to urethral obstruction (UO) and healthy cats. Blood and urine samples were collected from a group of 20 cats diagnosed with AKI secondary to urethral obstruction (GAKI; n=20) and clinically healthy cats (GC; n=15). The serum creatinine (sCre) and urinary creatinine (uCre), were measured by spectrophotometry, serum and urinary analyzes of sodium, potassium and chloride by ion selective electrode device and serum and urinary osmolarity by osmometer. The GAKI results were statistically compared with those of the CG using Student's t tests to assess normal data, while the Maan-Whitney test was used for non-normal data. A significant increase in the sCr, sK, FENa, FECl and RFI parameters of the GAKI cats when compared to the GC (p < 0.05). The sCl, USG, uCr, uK and uOSM parameters decreased significantly when compared between the two groups. Thus, given the established methodology and the results found, it is possible to infer that an increase in EFNa, EFCl in addition to the RFI and a decrease in USG and uOSM were associated with cats with AKI and can serve as markers of kidney damage, as well as monitoring the prognosis.

Whey beverage improves hydrating capacity of the soccer players

The hydration process is critical in soccer players. The hydrating capacity, energy recovery, and electrolyte excretion in urine were determined by the use of a whey beverage as a hydration medium for high-performance athletes compared to the effects of purified water and a sport beverage. The study was carried out through an approved research protocol, which contemplates the determination of hydrating capacity by monitoring body weight during a period of exercise and a subsequent hydration period. Energy recovery was determined by monitoring blood glucose levels and electrolyte excretion was performed by quantifying the concentration of sodium (Na+ ), potassium (K+ ), calcium (Ca2+) and magnesium (Mg2+) in urine samples provided by the participants during the research protocol. It was concluded that the whey beverage has an appropriate capacity for hydration and energy recovery, while with regard to minerals it was observed that it effectively regulates the excretion of Na+ , Ca2+ and Mg2+ .

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.

Diuretic, Kaliuretic and Anti-Natriuretic Properties of Aqueous Extract of Celosia trigyna L. (Amaranthaceae) on Wistar Rats

Aims: The purpose of this study was to determine the diuretic and electrolyte excretion properties of the aqueous extract of Celosia trigyna L. (Amaranthaceae) on female Wistar rats. Methodology: The extraction of active principles was done by macerating aerial parts of the plant. The administration of the extract and other products was done by single-dose gavage. Measurements of urinary flow rate (UFR), natriuria, kaliuria and chloruria were taken on urine collected for twenty-four hours after each product was administered. Diuretic activity (DA) and diuretic index (DI), natriuretic and saluretic effects, and carbonic anhydrase inhibition were calculated. A NaCl solution (0.9%) was used as a negative control; furosemide and aldactone were respectively used as hypokalemic and hyperkalemic positive controls. Results: We observed a significant increase in UFR, confirmed by the values of DA and DI, obtained after the administration of extract. For electrolyte excretion, we observed an increase of the kaliuria (p ˂ 0.001) and a decrease of natriuria (p ˂ 0.001) after the extract was administered; chloruria did not significantly changed. We also found a drastic anti-natriuretic dose-dependent effect while saluretic activity and carbonic anhydrase inhibition were not clearly observable. Conclusion: These results confirm the ethnobotanical data about diuretic effect of Celosia trigyna L. extract. This diuretic effect would be supported by a specific increase in K+ excretion suggesting that the extract is possibly hypokalemic. The anti-natriuretic effect suggests that extract possess an aldosterone-like properties.

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 <0.01) vs 6-fold in M ( P >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 <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).

Diurnal Regulation of Renal Electrolyte Excretion: The Role of Paracrine Factors

Many physiological processes, including most kidney-related functions, follow specific rhythms tied to a 24-h cycle. This is largely because circadian genes operate in virtually every cell type in the body. In addition, many noncanonical genes have intrinsic circadian rhythms, especially within the liver and kidney. This new level of complexity applies to the control of renal electrolyte excretion. Furthermore, there is growing evidence that paracrine and autocrine factors, especially the endothelin system, are regulated by clock genes. We have known for decades that excretion of electrolytes is dependent on time of day, which could play an important role in fluid volume balance and blood pressure control. Here, we review what is known about the interplay between paracrine and circadian control of electrolyte excretion. The hope is that recognition of paracrine and circadian factors can be considered more deeply in the future when integrating with well-established neuroendocrine control of excretion.

The selective mineralocorticoid receptor modulator AZD9977 reveals differences in mineralocorticoid effects of aldosterone and fludrocortisone

Introduction: AZD9977 is a novel mineralocorticoid receptor (MR) modulator, which in preclinical studies demonstrated organ protection without affecting aldosterone-regulated urinary electrolyte excretion. However, when tested in humans, using fludrocortisone as an MR agonist, AZD9977 exhibited similar effects on urinary Na+/K+ ratio as eplerenone. The aim of this study is to understand whether the contradictory results seen in rats and humans are due to the mineralocorticoid used. Materials and methods: Rats were treated with single doses of AZD9977 or eplerenone in combination with either aldosterone or fludrocortisone. Urine was collected for five to six hours and total amounts excreted Na+ and K+ were assessed. Results: AZD9977 dose-dependently increased urinary Na+/K+ ratio in rats when tested against fludrocortisone, but not when tested against aldosterone. Eplerenone dose-dependently increased urinary Na+/K+ ratio when tested against fludrocortisone as well as aldosterone. Conclusions: The data suggest that the contrasting effects of AZD9977 on urinary electrolyte excretion observed in rats and humans are due to the use of the synthetic mineralocorticoid fludrocortisone. Future clinical studies are required to confirm the reduced electrolyte effects of AZD9977 and the subsequent lower predicted hyperkalemia risk.