Electrolyte Excretion Research Articles

Chemical composition and diuretic, natriuretic and kaliuretic effects of extracts of Mimosa bimucronata (DC.) Kuntze leaves and its majority constituent methyl gallate in rats

Some species of the genus Mimosa showed promising results in previous investigations, which include diuretic effect; however, no chemical analyses or animal model has been conducted so far to evaluate the biological properties of M. bimucronata. Male Wistar rats received the oral treatment with vehicle; hydrochlorothiazide; methanolic extract from M. bimucronata (MEMB), dichloromethane (DCM) and ethyl acetate (EA) fractions or methyl gallate (MG). The cumulative urine volume, electrolytes excretion, pH and osmolality were determined at the end of the experiment. The chemical studies demonstrated that the phenolic compounds are the majorities in the plant, with the MG being the main substance identified. We showed that MEMB and EA fraction, but not DCM, exhibited diuretic and saluretic effects. Similarly, the MG also revealed diuretic, natriuretic and kaliuretic properties to both normotensive and spontaneously hypertensive rats. Atropine, a muscarinic receptor antagonist, fully prevented MG-induced diuresis and saluresis. In addition, MG did not alter the viability of A7r5 and L929 cell lines and neither stimulated nitric oxide generation. These findings suggest that M. bimucronata extracts and its majority compound MG present diuretic, natriuretic and kaliuretic properties, which was dependent on the activation of muscarinic acetylcholine receptor.

Specific Features of Electrolyte Excretion at the Early Stages of Arterial Hypertension in SHR Rats.

Daytime and nighttime systolic and diastolic BP was recorded in 23-week-old SHR and Wistar rats by telemetric monitoring. Urine concentrations of sodium, potassium, and calcium were determined in SHR rats during of light (07.00-19.00 h) and dark hours (19.00-07.00 h) at the age of 18, 19, 20, 21, 22, and 23 week; 23-week-old Wistar rats were used as the control. At early stages of the experiment, urine sodium concentration was elevated in SHR rats both at daytime and at night. Thereafter, this value declined and by 22-23 week was significantly lower than in normotensive Wistar rats, but only during daytime. Daytime potassium concentration significantly surpassed the control level during weeks 18-19 of the experiment, but later, a tendency to a decrease in this parameter was observed. Daytime calcium content in SHR rats did not significantly differ from the control throughout the experiment. At night, this value exceeded the control level by more than 2 times during weeks 18-19, but then returned to the level observed in normotensive animals.

Physiological regulation of the epithelial Na+ channel by casein kinase II.

epithelial Na+ channel, ENaC, is the final arbiter of sodium excretion in the kidneys. As such, discretionary control of ENaC by hormones is critical to the fine-tuning of electrolyte and water excretion and, consequently, blood pressure. Casein kinase 2 (CK2) phosphorylates ENaC. Phosphorylation by CK2 is necessary for normal ENaC activity. We tested the physiological importance of CK2 regulation of ENaC as the degree to which ENaC activity is dependent on CK2 phosphorylation in the living organism is unknown. This was addressed using patch-clamp analysis of ENaC in completely split-open collecting ducts and whole animal physiological studies of sodium excretion in mice. We also used ENaC-harboring CK2 phosphorylation site mutations to elaborate the mechanism. We found that ENaC activity in ex vivo preparations of murine collecting duct had a significant decrease in activity in response to selective antagonism of CK2. In whole animal experiments selective antagonism of CK2 caused a natriuresis similar to benzamil, but not additive to benzamil, suggesting an ENaC-dependent mechanism. Regulation of ENaC by CK2 was abolished by mutation of the canonical CK2 phosphorylation sites in beta and gamma ENaC. Together, these results demonstrate that the appropriate regulation of ENaC by CK2 is necessary for the normal physiological role played by this key renal ion channel in the fine-tuning of sodium excretion.

Association Between Urinary Sodium and Potassium Excretion and Blood Pressure Among Adults in the United States: National Health and Nutrition Examination Survey, 2014.

Higher levels of sodium and lower levels of potassium intake are associated with higher blood pressure. However, the shape and magnitude of these associations can vary by study participant characteristics or intake assessment method. Twenty-four-hour urinary excretion of sodium and potassium are unaffected by recall errors and represent all sources of intake, and were collected for the first time in a nationally representative US survey. Our objective was to assess the associations of blood pressure and hypertension with 24-hour urinary excretion of sodium and potassium among US adults. Cross-sectional data were obtained from 766 participants age 20 to 69 years with complete blood pressure and 24-hour urine collections in the 2014 National Health and Nutrition Examination Survey, a nationally representative survey of the US noninstitutionalized population. Usual 24-hour urinary electrolyte excretion (sodium, potassium, and their ratio) was estimated from ≤2 collections on nonconsecutive days, adjusting for day-to-day variability in excretion. Outcomes included systolic and diastolic blood pressure from the average of 3 measures and hypertension status, based on average blood pressure ≥140/90 and antihypertensive medication use. After multivariable adjustment, each 1000-mg difference in usual 24-hour sodium excretion was directly associated with systolic (4.58 mm Hg; 95% confidence interval [CI], 2.64-6.51) and diastolic (2.25 mm Hg; 95% CI, 0.83-3.67) blood pressures. Each 1000-mg difference in potassium excretion was inversely associated with systolic blood pressure (-3.72 mm Hg; 95% CI, -6.01 to -1.42). Each 0.5 U difference in sodium-to-potassium ratio was directly associated with systolic blood pressure (1.72 mm Hg; 95% CI, 0.76-2.68). Hypertension was linearly associated with progressively higher sodium and lower potassium excretion; in comparison with the lowest quartile of excretion, the adjusted odds of hypertension for the highest quartile was 4.22 (95% CI, 1.36-13.15) for sodium, and 0.38 (95% CI, 0.17-0.87) for potassium (P<0.01 for trends). These cross-sectional results show a strong dose-response association between urinary sodium excretion and blood pressure, and an inverse association between urinary potassium excretion and blood pressure, in a nationally representative sample of US adults.

Ethnopharmacological approaches to kidney disease-prospecting an indigenous species from Brazilian Pantanal

Ethnopharmacological relevanceAlthough Luehea divaricata Mart. (Malvaceae) is popularly used by the population of the Brazilian Pantanal for the treatment of different types of kidney diseases, no study has been carried out to prove this ethnobotanical indication. AimTo investigate the possible cardiorenal effects of an herbal preparation obtained from L. divaricata leaves. Materials and methodsFirst, to provide quality control standards, a detailed morphological and microchemical characterization of L. divaricata leaves was performed. Then, the purified aqueous extract was obtained from the leaves of this species (ESLD) and a thorough phytochemical characterization was performed. Subsequently, acute oral toxicity test was performed after single administration of different doses (5, 50, 300, 2000mg/kg) in male and female Wistar rats. Finally, the diuretic, hypotensive and antioxidant properties of ESLD (30, 100, 300mg/kg) were evaluated after acute and prolonged treatment and the role of angiotensin converting enzyme, aldosterone, vasopressin, and nitric oxide in these effects was investigated. ResultsAnalyses performed by liquid chromatography–mass spectrometry showed that the main secondary metabolites present in ESLD were flavonol O-glycosides and flavone C-glycosides. Acute and prolonged treatment with ESLD was able to expressively increase urinary volume and electrolyte excretion. Mean blood pressure and systolic blood pressure were also significantly reduced after acute treatment. Moreover, treatment with ESLD was able to reduce thiobarbituric acid reactive species and increase serum nitrate levels. ConclusionThe data obtained showed that ESLD has an important diuretic and hypotensive effect, which is probably dependent on the reduction of oxidative stress and increased bioavailability of nitric oxide.

Antioxidant and diuretic activity of co-administration of Capparis spinosa honey and propolis in comparison to furosemide.

To study the antioxidant properties of Capparis spinosa (C.spinosa) honey and propolis and the effect of combined honey and propolis administration on urine volume and electrolytes in rats. C.spinosa honey [1000mg/kg body weight (b.wt)], propolis (100mg/kg b.wt), honey/propolis mixture (C. spinosa honey 1000 mg/kg b.wt/ propolis extract 100 mg/kg b.wt ), distilled water (1mL/kg b.wt) and furosemide (10mg/kg b.wt) were orally administered to five groups of rats for 21d. Urine volume, blood and urine sodium, potassium and chloride were measured. The antioxidant activity of propolis and honey was assessed and their total phenols and flavonoids were determined. Propolis and C.spinosa honey contain polyphenols including flavonoids and propolis demonstrated higher antioxidant activities than honey. Honey significantly increased urine volume and urine electrolyte excretion. Propolis had no significant effect on urine volume, but co-administration of propolis and honey caused significant diuresis. No major changes were observed in plasma electrolytes with the use of honey, propolis or their combination. Honey and propolis have antioxidant activity and contain polyphenols including flavonoids that are more pronounced in propolis. Honey has a significant diuretic activity alone or in combination with propolis. This is the first study comparing the diuretic effect of co-administration of propolis and C.spinosa honey with furosemide.

Diuretic Activity of Compatible Triterpene Components of Alismatis rhizoma.

Alismatis rhizoma (AR), the dried rhizoma of Alisma orientale Juzepzuk (Alismataceae), is a traditional Chinese medicine. AR is an important part of many prescriptions and is commonly used as a diuretic agent in Asia. This study aimed to evaluate the diuretic effects of total triterpene extract (TTE) and triterpene component compatibility (TCC, the mixture of alisol B 23-acetate, alisol B, alisol A 24-acetate, alisol A, and alisol C 23-acetate) of AR in saline-loaded rats. The optimal diuretic TCC of AR was optimized using a uniform design. Different doses (5, 20, and 40 mg/kg) of TTE and TCC groups (N1–N8) were orally administered to rats. Urinary excretion rate, pH, and electrolyte excretion were measured in the urine of saline-loaded rats. Results showed that TTE doses increased urine volume and electrolyte excretion compared with the control group. All uniformly designed groups of TCC also increased urine excretion. In addition, optimal diuretic TCC was calculated (alisol B 23-acetate: alisol B: alisol A 24-acetate: alisol A: alisol C 23-acetate 7.2:0.6:2.8:3.0:6.4) and further validated by saline-loaded rats. This study demonstrated that TTE presented a notable diuretic effect by increasing Na+, K+, and Cl− displacements. The most suitable TTC compatible proportion of alisol B 23-acetate: alisol B: alisol A 24-acetate: alisol A: alisol C 23-acetate for diuretic activity was validated, and triterpenes were the material basis for the diuretic activity of AR.

A population-based approach to assess the heritability and distribution of renal handling of electrolytes

The handling of electrolytes by the kidney is essential for homeostasis. However, the heritability of these processes, the first step in gene discovery, is poorly known. To help clarify this, we estimated the heritability of serum concentration, urinary excretion, renal clearance, and fractional excretion of sodium, potassium, magnesium, calcium, phosphate, and chloride in a population-based study. Nuclear families were randomly selected from the general population in Lausanne, Geneva, and Bern, Switzerland, and urine collected over 24-hour periods. We used the ASSOC program (S.A.G.E.) to estimate narrow sense heritability, including sex, age, body mass index, and study center as covariates in the model. The 1128 participants, from 273 families, had a mean age of 47 years, body mass index of 25.0 kg/m2, and an estimated glomerular filtration rate (CKD-EPI) of 98 mL/min/1.73 m2. The heritability of serum concentration was highest for calcium, 37% and lowest for sodium, 13%. The heritability of 24-hour urine clearances, excretions, and fractional excretions ranged from 15%, 10%, and 16%, respectively, for potassium to 45%, 44%, and 51%, respectively, for calcium. All probability values were significant. The heritability for phosphate-related phenotypes was lower than that for calcium. Thus, the serum and urine concentrations as well as urinary excretion and renal handling of electrolytes are heritable in the general adult population. The phenotypic variance attributable to additive genetic factors was variable and was higher for calcium. These results pave the way for identifying genetic variants involved in electrolyte homeostasis in the general population.

Abstract P151: Salt Sensitivity in Male and Female C57BL/6J Mice: Role of Renal Angiotensin and Dopamine Receptors and Sodium Transporters

To test if there is a sex difference in the salt sensitivity of C57Bl/6J mice, we studied blood pressure (BP), renal dopamine receptors, and sodium transporters in response to high salt diet (4% NaCl, 1 wk) and candesartan. Similar to males, the night-time systolic BP (SBP, telemetry, n=4) in females started to increase on day 1, peaked on day 2 (130±1 vs 117±1, mm Hg) and remained at high levels (126±1); the daytime SBP started to increase on day 2 that became significant on day 6 (124±1 vs 111±1). The high salt-diet induced-increase in SBP was prevented by candesartan (1 mg/kg, 1 wk, subcutaneously via osmotic mini-pump) (82±3 vs. 117±2 in males; 86±2 vs. 121±1 in females, under anesthesia, n=5/group). There were no sex differences in the SBP response to diet and candesartan, food and water intakes, urinary excretions of water and electrolytes, and serum concentrations of creatinine and electrolytes on high and normal salt diet. In females fed a high salt diet, candesartan increased renal D 1 R (151±12, immunoblotting, % of control, n=5/group) and D 5 R (156±5) but not D 2 R, D 3 R , or D 4 R protein expression, increased renal mRNA expression of D 1 R(160±17) but not D 5 R (real-time PCR), and decreased the renal protein expressions of sodium-hydrogen exchanger isoform 3 (36±6), sodium-potassium-2 chloride cotransporter (8±2), sodium-chloride cotransporter (30±3), and α (55±4), β (60±8) and γ (9±1) epithelial sodium channel, but not type 2 sodium phosphate cotransporter and α1Na + K + ATPase. Those changes were also seen in males except that renal D 1 R protein expression was not increased. Under normal salt intake, AT 1A R KO females (C57Bl/6J background) had increased renal protein expressions of D 1 R (152±8), D 5 R (131±6), and D 4 R (114±4), but not D 2 R and D 3 R; renal protein expressions of sodium-hydrogen exchanger isoform 3 (47±8), sodium-potassium-2 chloride cotransporter (52±11), and α (42±9) and γ (46±7) epithelial sodium channel were decreased. We conclude that the increase in BP caused by high salt diet and the effect of AT 1 R blockade on BP, renal dopamine receptors and sodium transporters are similar in male and female C57Bl/6J mice . The consequences of the sex-related differential regulation of D 1 R and D 5 R, in pathophysiology, other than BP, remain to be determined.

Abstract 035: Fetal Growth Restriction is Associated with Spontaneous Gestational Hypertension in African Green Monkeys

Hypertensive pregnancy disorders, including gestational hypertension (GH) and preeclampsia (PE), are a major cause of worldwide maternal and fetal mortality. The only treatment for PE is delivery of the infant and placenta. Elucidating the cause of GH and PE is critical for improving diagnosis and therapy. This study provides the pregnant African Green Monkey (AGM; Chlorocebus aethiops sabeus ) as the first known nonhuman model of spontaneous GH with pathophysiological characteristics of PE. Here, maternal blood pressures, water balance, renal electrolyte excretion, and fetal birth weight are characterized in AGMs. Following ketamine sedation (15 mg/kg i.m.), systolic blood pressures (SBP) were obtained in AGMs using forearm plethysmography. Animals were defined as normotensive (NT; SBP &lt; 120 mmHg), hypertensive (HT; SBP ≥ 140 mmHg), or GH (SBP increased from non-HT to ≥15 mmHg in 3 rd trimester). Nonpregnant SBP for NT AGMs was 98.7 ± 3.7 mmHg (n = 18), for HT AGMs was 154.7 ± 5.7 mmHg (n = 6), and for GH AGMs was 111.3 ± 6.1 mmHg (n = 7). Third trimester SBP for NT AGMs was 102.9 ± 4.0 mmHg (n = 13), and for GH AGMs was 146.3 ± 4.6 mmHg (n = 7). SBP decreased by 5.2 ± 8.1 mmHg in NT pregnancies (n = 5) and increased 35.0 ± 8.1 mmHg in GH pregnancies (n = 6).There were no differences in water intake or 24-hour urinary Na + /K + excretions among AGMs regardless of group. Infant birth weight was lower in GH AGMs than that of NT AGMs (GH 233.1 ± 27.0 g, n = 5; NT 314.5 ± 16.7 g, n = 7; p&lt;0.05). These data show GH in the AGM is associated with fetal growth restriction, decreased late pregnancy SBP in controls, and increased SBP in GH, similar to human pregnancies. Future studies include examination of renal glomerular structure, placental histopathology and transcriptomics, protein excretions, and plasma PE biomarkers to further establish this animal as a spontaneous model of GH and possibly PE. The AGM, having diverged from the human lineage approximately 29 million years ago, has close genetic homology to humans. This evolutionary history has led to a shared organ physiology, circadian rhythmicity, upright posture, and complex familial and behavior systems with humans, making it a highly translational animal model of hypertensive pregnancy disorders critical to cardiovascular research.

Abstract P316: Gonad Dependent Changes in Kallikrein Kinin System Behavior and Renal Electrolyte Excretion After Rectifying Outer Medulla K + Channel Blockade in Spontaneously Hypertensive Rats

The kallikrein kinin system (KKS) is involved in blood pressure (BP) regulation by a mechanism not completely defined. Our previous reports have shown that high K + intake or prepuberal gonadectomy (Gx) diminish BP with a simultaneous increase in urine kallikrein activity (UKa) and plasma aldosterone (PA) levels, revealing a link between those systems. Thus, since K + may be involved in the regulation of KKS, we explored the rectifying outer medulla K + (ROMK) channel blockade using glibenclamide (Gli) in different gonad contexts.Spontaneously hypertensive rats of both sexes, half of them Gx at weaning, were studied at 12 weeks of age (n = 32). Glucose solution (4%) with or without Gli (10 mg/kg bwt) was orally administered in the last 3 days of the experiment. We analyzed BP, glomerular filtration rate, PA, daily urine Na + and K + excretion and UKa. Renal cortex kallikrein activity (RKa) and UKa were determined by colorimetric assay. Renal mRNA levels of Kcjn1 (ROMK), Atp1α1 (Na + K + Atpase) and Klk1 (kallikrein 1) genes were determined by quantitative real time PCR. Urine Na + /K + increased after Gli treatment (0.55 ± 0.03 vs 1.34 ± 0.30, p &lt;0.05) due to a K + excretion decrease in intact male and ovariectomized rats and to a Na + excretion increase in intact female. These changes were concomitant with increased GFR within the normal range (0.51 ± 0.06 vs 0.76 ± 0.06 ml/min/100g bwt p &lt; 0.01) and no differences in BP and PA among groups. After Gli treatment, renal cortex Klk1 and RKa levels increased in intact males (297 and 137 %, p &lt; 0.05, respectively), while in orchidectomized group Klk1 and UKa levels increased (179 and 230 %, p &lt; 0.05; respectively). Kcjn1 and Atp1α1 mRNA levels decreased in renal medulla of all groups (1.29 ± 0.28 vs 0.32 ± 0.11 and 0.94 ± 0.23 vs 0.20 ± 0.02, p &lt; 0.01, respectively). Taken together, gonad dependent changes were seen in urine Na + and K + excretion and KKS behavior after ROMK blockade without changes in the BP and aldosterone. Moreover, the repression in Kcjn1 and Atp1α1 genes could be related to the observed ion transport changes.

Coffee with High but Not Low Caffeine Content Augments Fluid and Electrolyte Excretion at Rest.

Low levels of caffeine ingestion do not induce dehydration at rest, while it is not clear if larger doses do have an acute diuretic effect. The aim of the present investigation was to examine the acute effect of low and high levels of caffeine, via coffee, on fluid balance in habitual coffee drinkers (at least one per day) at rest. Ten healthy adults (eight males and two females; age: 27 ± 5 years, weight: 89.5 ± 14.8 kg, height: 1.75 ± 0.08 m, and body mass index: 29.1 ± 4.4 kg m-2) ingested 200 mL of water (W), coffee with low caffeine (3 mg kg-1, LCAF), or coffee with high caffeine (6 mg kg-1, HCAF) on three respective separate occasions. All sessions were performed at 09:00 in the morning in a counterbalanced, crossover manner, at least 5 days apart. Subjects remained in the laboratory while urine samples were collected every 60 min for 3 h post ingestion. Absolute caffeine consumption was 269 ± 45 and 537 ± 89 mg for the LCAF and HCAF, respectively. Coffee ingestion at the HCAF trial induced greater diuresis during the 3-h period (613 ± 101 mL, P < 0.05), when compared to W (356 ± 53 mL) and LCAF (316 ± 38 mL). In addition, cumulative urinary osmotic excretion was significantly greater in the HCAF (425 ± 92 mmol, P < 0.05), as compared to the W (249 ± 36 mmol) and LCAF (177 ± 16 mmol) trials. The data indicate that caffeine intake of 6 mg kg-1 in the form of coffee can induce an acute diuretic effect, while 3 mg kg-1 do not disturb fluid balance in healthy casual coffee drinking adults at rest.

Evaluation of in Vivo Diuretic Activity of Methanolic Extracts of Clutia Abyssinica (Euphorbiaceae) Roots in Wistar Albino Rats

Introduction: Most parts of the plant Clutia abyssinica is traditionally used in different diseases because of their medicinal properties. The roots are widely used traditionally, as diuretic purpose, liver problems, enlarged spleen and kidney problems. The present study was carried out to evaluate the diuretic effect of methanolic extracts of Clutia abyssinica roots in rats in comparison with standard drug furosemide. Methodology: Thirty rats of either sex were randomly allocated into five groups of six each. The rats were pretreated with physiological saline (0.9% NaCl, po) at a dose of 25 ml/kg, to impose uniform water and salt load. The control group received normal saline (20 ml/kg po), the standard group received furosemide (10mg/kg, po) and the test groups were administered different doses of the crude methanolic extract (100, 200 and 400mg/kg, po) respectively and urine was collected from individual rat for a period of 24 hrs. The urine volume and concentration of urine electrolytes were measured. Result: At medium (M200) and maximum (M400) doses of Clutia abyssinica had a significant urine output at the end of 6 hr (p<0.001) and 24hr (p<0.05) when compared with control group. Effect on electrolyte excretion showed in both 6hr and 24hr had an increased natriuresis (p<0.001 for both time of collection) and kaliuresis (p<0.05 for 6hr and p<0.001 for 24hr urine) at M400 dose, while the kaliuresis effect was smaller at M100 doses when compared with standard. The plant was also found to be safe at a maximum dose of 2000 mg/kg for methanolic extracts. Conclusions: These findings indicate that crude extract of Clutia abyssinica roots has good diuretic activity on rat model. However, future studies should focus on its exact mechanisms of action and isolating the phytochemical component(s) responsible for diuresis. Keywords: Diuretics, Clutia abyssinica, natriuretic index, saluretic index

Robust circadian clock oscillation and osmotic rhythms in inner medulla reflecting cortico-medullary osmotic gradient rhythm in rodent kidney

Circadian clocks in mammals function in most organs and tissues throughout the body. Various renal functions such as the glomerular filtration and excretion of electrolytes exhibit circadian rhythms. Although it has been reported that the expression of the clock genes composing molecular oscillators show apparent daily rhythms in rodent kidneys, functional variations of regional clocks are not yet fully understood. In this study, using macroscopic bioluminescence imaging method of the PER2::Luciferase knock-in mouse kidney, we reveal that strong and robust circadian clock oscillation is observed in the medulla. In addition, the osmotic pressure in the inner medulla shows apparent daily fluctuation, but not in the cortex. Quantitative-PCR analysis of the genes contributing to the generation of high osmotic pressure or the water re-absorption in the inner medulla, such as vasopressin receptors (V1aR, V2R), urea transporter (UT-A2) and water channel (Aqp2) show diurnal variations as well as clock genes. Deficiency of an essential clock gene Bmal1 impairs day-night variations of osmotic pressure gradient in the inner medulla, suggesting that circadian clocks in the medulla part of the kidney may regulate the circadian rhythm of cortico-medullary osmotic pressure gradient, and may contribute physiological day-night rhythm of urination.

Tubuloglomerular feedback responses in offspring of dexamethasone-treated ewes.

Via developmental programming, prenatal perturbations, such as exposure to glucocorticoids and maternal malnutrition alter kidney development and contribute to the development of hypertension. To examine the possibility that alterations in tubuloglomerular feedback (TGF) contribute to the development of hypertension in offspring following maternal dexamethasone treatment (Dex) in early gestation, studies were conducted in fetal sheep and lambs. Pregnant ewes were infused with dexamethasone (0.48 mg/h) at 26-28 days gestation. No differences were observed in mean arterial pressure, glomerular filtration rate. or electrolyte excretion rates between the Dex and Untreated fetuses or lambs. Gestational exposure to Dex markedly enhanced TGF sensitivity, as the turning point in Dex-treated fetuses was significantly lower (12.9 ± 0.9 nl/min; P < 0.05) compared with Untreated fetuses (17.0 ± 1.0 nl/min). This resetting of TGF sensitivity persisted after birth (P < 0.01). TGF reactivity did not differ between the groups in fetuses or lambs. In response to nitric oxide inhibition, TGF sensitivity increased (the turning point decreased) and reactivity increased in Untreated fetuses and lambs, but these effects were blunted in the Dex-treated fetuses and lambs. Our data suggest that an altered TGF response may be an underlying renal mechanism contributing to the development of hypertension in the Dex model of fetal programming. The lower tonic level of NO production in these dexamethasone-exposed offspring may contribute to the development of hypertension as adults.

Diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats: Role of muscarinic acetylcholine receptors.

Luteolin is a very common phenolic compound found in a wide variety of natural products. Although several biological properties have already been described regarding the beneficial effect of luteolin in the cardiovascular and renal system, no scientific research explored its potential effect as a diuretic agent in experimental trials. Groups of male normotensive (NTR) and spontaneously hypertensive rats (SHR) were orally treated with vehicle, hydrochlorothiazide or luteolin. In another experimental set, in order to verify the possible mechanisms of luteolin-induced diuresis, NTR were treated with vehicle, hydrochlorothiazide, amiloride, L-NAME, indomethacin or atropine, 1h before receiving luteolin. The cumulative urine volume, electrolytes excretion, pH and osmolality were measured at the end of the experiment (after 8h). Luteolin, at dose of 3mg/kg, was able to induce both diuretic and natriuretic effect in NTR and SHR groups, without interfering with urinary pH, K+ or Cl- levels. While Ca2+ content remained unchanged in urine from luteolin-treated group of NTR, luteolin reduced Ca2+ excretion in urine from SHR. The treatment with HCTZ and amiloride intensified luteolin-induced diuresis and natriuresis, with an interesting potassium-sparing effect, in addition to an increase in urinary osmolality levels. Moreover, the diuretic and natriuretic action of luteolin was fully avoided in the presence of atropine, a non-selective muscarinic receptor antagonist. This study revealed the diuretic and natriuretic effect of luteolin in normotensive and hypertensive rats. Our data also showed the involvement of muscarinic acetylcholine receptors for the renal effects of luteolin.

Ethnopharmacological investigations of the cardio-renal properties of a native species from the region of Pantanal, state of Mato Grosso do Sul, Brazil

Ethnopharmacological relevanceAcanthospermum hispidum DC. is an important medicinal herb that belongs to family Asteraceae, popularly used as a diuretic and hypotensive in the region of Pantanal, state of Mato Grosso do Sul, Brazil. Despite the relevance of this species throughout the country, there are no detailed studies about its possible ethnobotanical indication. AimTo carry out a detailed ethnopharmacological investigation of the cardio-renal properties of A. hispidum. Materials and methodsFirst, a detailed morpho-anatomical study with the purpose of characterizing and providing quality control parameters for the species was carried out. Then, purified aqueous extract (ESAH) was obtained and a detailed phytochemical investigation about its main secondary metabolites was performed. In addition, a thorough acute toxicological study was conducted to evaluate the actual toxic effects of this preparation. Finally, the possible diuretic and hypotensive effects of ESAH on male Wistar rats (30, 100, 300mg/kg; intraduodenally) were evaluated, and using pharmacological antagonists or inhibitors, the involvement of prostaglandin/cAMP and nitric oxide/cGMP pathway and potassium channels in ESAH-induced hypotension was investigated. ResultsThe analyses performed by liquid chromatography–mass spectrometry showed that the main secondary metabolites present in ESAH were phenolic compounds, such as caffeoylquinic acids (chlorogenic acid), dicaffeoylquinic acids and glycosylated flavonoids (quercetin glucoside and galactoside). ESAH did not induce any acute toxic effects and did not affect the urinary volume or renal excretion of electrolytes in Wistar rats. On the other hand, intraduodenal administration of ESAH induces a significant acute hypotensive effect. Previous treatment with N(G)-nitro-L-arginine methyl ester, methylene blue, or tetraethylammonium fully avoided the hypotensive effect of ESAH. All other parameters were not affected by treatment with ESAH. ConclusionData obtained in this study allow us to suggest that ESAH obtained from A. hispidum presents an important acute hypotensive effect, which appears to be dependent on the nitric oxide/cGMP pathway. This study presents new evidences about the therapeutic potential of this species when acute hypotensive response is required.

Oleanolic acid modulates the renin-angiotensin system and cardiac natriuretic hormone concomitantly with volume and pressure balance in rats

Oleanolic acid is known to possess beneficial effects on the regulation of the cardiovascular homeostasis. However, the exact nature of the role of oleanolic acid on the regulation of body fluid balance and blood pressure homeostasis and its mechanisms involved are not well defined. Experiments were performed to identify the effects of oleanolic acid on the renin-angiotensin system and cardiac natriuretic hormone (ANP) system, and also renal function and blood pressure in normotensive and renovascular hypertensive rats. The change in the plasma levels of hormones and the expressions of renin, angiotensin II receptors, ANP, natriuretic peptide receptor-C, M2 muscarinic receptor and GIRK4 were determined in the kidney, heart and aorta. Oleanolic acid was administered orally for 1 or 3 weeks. Here, we found that oleanolic acid suppressed plasma levels of renin activity and aldosterone and intrarenal levels of renin and angiotensin II type 1 receptor expression and increased angiotensin II type 2 receptor in normotensive and hypertensive rats. Also, oleanolic acid increased plasma levels of ANP. Further, oleanolic acid suppressed angiotensin II type 1 receptor and natriuretic peptide receptor-C expression and increased angiotensin II type 2 receptor and ANP expression in the heart and aorta. Along with these changes, oleanolic acid accentuated urinary volume, electrolyte excretion and glomerular filtration rate in normotensive rats and suppressed arterial blood pressure in hypertensive rats. These findings suggest that beneficial effects of oleanolic acid on the cardiorenal system are closely associated with its roles on the renin-angiotensin system and cardiac natriuretic hormone system.

Perivascular radiofrequency renal denervation lowers blood pressure and ameliorates cardiorenal fibrosis in spontaneously hypertensive rats.

BackgroundCatheter-based renal denervation (RDN) is a promising approach to treat hypertension, but innervation patterns limit the response to endovascular RDN and the post-procedural renal artery narrowing or stenosis questions the endovascular ablation strategy. This study was performed to investigate the anti-hypertensive and target organ protective effects of perivascular RDN in spontaneously hypertensive rats (SHR).MethodsSHR and normotensive Wistar-Kyoto (WKY) rats were divided into sham group (n = 10), radiofrequency ablation group (n = 20) in which rats received bilateral perivascular ablation with radiofrequency energy (2 watts), and chemical (10% phenol in 95% ethanol) ablation group (n = 12). The tail-cuff blood pressure was measured before the ablation and on day 14 and day 28 after the procedure. The plasma levels of creatinine, urea nitrogen, and catecholamines, urinary excretion of electrolytes and protein, and myocardial and glomerular fibrosis were analyzed and compared among the groups on day 28 after the procedure.ResultsWe identified that 2-watt is the optimal radiofrequency power for perivascular RDN in rats. Perivascular radiofrequency and chemical ablation achieved roughly comparable blood pressure reduction in SHR but not in WKY on day 14 and day 28 following the procedure. Radiofrequency-mediated ablation substantially destroyed the renal nerves surrounding the renal arteries of both SHR and WKY without damaging the renal arteries and diminished the expression of tyrosine hydroxylase, the enzyme marker for postganglionic sympathetic nerves. Additionally, perivascular radiofrequency ablation also decreased the plasma catecholamines of SHR. Interestingly, both radiofrequency and chemical ablation decreased the myocardial and glomerular fibrosis of SHR, while neither increased the plasma creatinine and blood urea nitrogen nor affected the urinary excretion of electrolytes and protein when compared to sham group.ConclusionsRadiofrequency-mediated perivascular RDN may become a feasible procedure against hypertension, and provide similar anti-hypertensive and target organ protective effects as does the chemical ablation.

Circadian Rhythm in Kidney Tissue Oxygenation in the Rat

Blood pressure, renal hemodynamics, electrolyte, and water excretion all display diurnal oscillation. Disturbance of these patterns is associated with hypertension and chronic kidney disease. Kidney oxygenation is dependent on oxygen delivery and consumption that in turn are determined by renal hemodynamics and metabolism. We hypothesized that kidney oxygenation also demonstrates 24-h periodicity. Telemetric oxygen-sensitive carbon paste electrodes were implanted in Sprague-Dawley rats (250–300 g), either in renal medulla (n = 9) or cortex (n = 7). Arterial pressure (MAP) and heart rate (HR) were monitored by telemetry in a separate group (n = 8). Data from 5 consecutive days were analyzed for rhythmicity by cosinor analysis. Diurnal electrolyte excretion was assessed by metabolic cages. During lights-off, oxygen levels increased to 105.3 ± 2.1% in cortex and 105.2 ± 3.8% in medulla. MAP was 97.3 ± 1.5 mmHg and HR was 394.0 ± 7.9 bpm during lights-off phase and 93.5 ± 1.3 mmHg and 327.8 ± 8.9 bpm during lights-on. During lights-on, oxygen levels decreased to 94.6 ± 1.4% in cortex and 94.2 ± 8.5% in medulla. There was significant 24-h periodicity in cortex and medulla oxygenation. Potassium excretion (1,737 ± 779 vs. 895 ± 132 μmol/12 h, P = 0.005) and the distal Na+/K+ exchange (0.72 ± 0.02 vs. 0.59 ± 0.02 P < 0.001) were highest in the lights-off phase, this phase difference was not found for sodium excretion (P = 0.4). It seems that oxygen levels in the kidneys follow the pattern of oxygen delivery, which is known to be determined by renal blood flow and peaks in the active phase (lights-off).