scholarly journals Acute hypoxia and endogenous renal endothelin.

1994 ◽  
Vol 4 (11) ◽  
pp. 1920-1924
Author(s):  
A Nir ◽  
A L Clavell ◽  
D Heublein ◽  
L L Aarhus ◽  
J C Burnett

Endothelin (ET) is a potent vasoconstrictor peptide of endothelial cell origin. Recent studies have suggested a nonvascular paracrine and/or autocrine role for endothelin in the kidney. This study was designed to elucidate the renal ET response to acute moderate hypoxia, as reflected by urinary ET excretory rate and renal tissue ET immunoreactivity, and to correlate these responses to the hemodynamic and excretory changes during hypoxia. Experiments were conducted in two groups of anesthetized dogs: hypoxic group (10% O2 ventilation: PO2, 44 mm Hg; N = 7) and time control group (room air ventilation: PO2, 111 mm Hg; N = 6). After 60 min of hypoxia or room air ventilation, kidneys were harvested and stained immunohistochemically for ET. Acute moderate hypoxia was associated with significant increases in urinary ET excretion, urine flow, urinary sodium excretion, and fractional excretion of sodium (P < 0.05). There was no significant change in GFR, RBF, renal vascular resistance, or mean arterial pressure. Renal immunohistochemistry for ET revealed increased staining in the proximal and distal tubules in the hypoxic group as compared with controls. This study demonstrates that acute moderate hypoxia results in increased urinary ET excretion and renal tubular ET immunoreactivity, in association with diuresis and natriuresis, and suggests a nonvascular role of endogenously produced renal ET in the regulation of sodium homeostasis during hypoxia.

1991 ◽  
Vol 261 (4) ◽  
pp. F567-F570 ◽  
Author(s):  
A. A. Khraibi

In Okamoto spontaneously hypertensive rats (SHR), elevated arterial blood pressure is not transmitted to the renal interstitium, and therefore pressure natriuretic and diuretic responses are attenuated. The objective of this study was to determine the effect of increasing renal interstitial hydrostatic pressure (RIHP) by direct renal interstitial volume expansion (DRIVE) on natriuresis and diuresis of SHR and Wistar-Kyoto rats (WKY). Unilateral nephrectomy and implantation of two polyethylene (PE) matrices were performed 3-4 wk before the acute experiment. Four groups of rats, two experimental and two time control, were used. A control clearance period was taken in all groups. In experimental groups and at the beginning and middle of the second period DRIVE was accomplished by bolus injection of a solution of 2.5% human albumin in saline directly into interstitium through one of the PE matrices. In time-control groups saline was infused in renal interstitium at the beginning of the second period. The second PE matrix was used to continuously measure RIHP in all groups. In experimental groups, DRIVE produced a significant increase in RIHP from 3.8 +/- 0.4 to 5.7 +/- 0.8 mmHg (P less than 0.05) in SHR and 4.3 +/- 0.4 to 7.1 +/- 0.5 mmHg (P less than 0.05) in WKY. In both groups the significant increase in RIHP was associated with significant increases in urinary sodium excretion (UNaV), fractional excretion of sodium (FENa), and urine flow rate (V).(ABSTRACT TRUNCATED AT 250 WORDS)


2018 ◽  
Vol 43 (9) ◽  
pp. 956-968 ◽  
Author(s):  
Quadri K. Alabi ◽  
Rufus O. Akomolafe ◽  
Modinat A. Adefisayo ◽  
Olaoluwa S. Olukiran ◽  
Aliyat O. Nafiu ◽  
...  

The beneficial effects of kolaviron, a natural biflavonoid from the seeds of Garcinia kola, have been attributed to its antioxidant and anti-inflammatory activities. This study was designed to investigate the renoprotective effect of kolaviron in rat model of diclofenac (DFC)-induced acute renal failure. Thirty-five male Wistar rats were divided into 7 groups of 5 rats each as follows: a control group that received propylene glycol orally and treatment groups that received DFC, DFC recovery, DFC followed by kolaviron at 3 different doses, and kolaviron only. DFC-treated rats showed sluggishness, illness, and anorexia. Their urine contained appreciable protein, glucose, and ketone bodies. Histopathological examination of their kidneys revealed profound acute tubular necrosis. DFC treatment significantly increased levels of plasma creatinine, urea, sodium, chloride, potassium ions, and increased renal tissue activities of superoxide dismutase, catalase, levels of malondialdehyde, and hydrogen peroxide. Fractional excretion of sodium and potassium and renal tissue levels of reduced glutathione and prostaglandin E2 (PGE2) decreased significantly in DFC-treated groups. However, kolaviron administration significantly reduced the toxic effect of DFC on PGE2 release; plasma levels of creatinine, urea, glucose, and electrolytes; and significantly attenuated renal tubular and oxidative damages. Furthermore, the effects of DFC administration on food consumption, water intake, urine output and urine protein, glucose, ketone bodies, and electrolytes were significantly attenuated in animals treated with kolaviron. The results suggested that kolaviron ameliorated DFC-induced kidney injury in Wistar rats by decreasing renal oxidative damage and restoration of renal PGE2 release back to the basal levels.


2015 ◽  
Vol 3 (3) ◽  
pp. 116-125 ◽  
Author(s):  
Bulent Ergin ◽  
Coert J. Zuurbier ◽  
Rick Bezemer ◽  
Asli Kandil ◽  
Emre Almac ◽  
...  

AbstractBackground and objectives: Acute kidney injury (AKI) is a clinical condition associated with a degree of morbidity and mortality despite supportive care, and ischemia/reperfusion injury (I/R) is one of the main causes of AKI. The pathophysiology of I/R injury is a complex cascade of events including the release of free oxygen radicals followed by damage to proteins, lipids, mitochondria, and deranged tissue oxygenation. In this study, we investigated whether the antioxidant ascorbic acid would be able to largely prevent oxidative stress and consequently, reduce I/R-related injury to the kidneys in terms of oxygenation, inflammation, and renal failure. Materials and methods: Rats were divided into three groups (n = 6/group): (1) a time control group; (2) a group subjected to renal ischemia for 60 min by high aortic occlusion followed by 2 h of reperfusion (I/R); and (3) a group subjected to I/R and treated with an i.v. 100 mg/kg bolus ascorbic acid 15 min before ischemia and continuous infusion of 50 mg/kg/hour for 2 h during reperfusion (I/R + AA). We measured renal tissue oxidative stress, microvascular oxygenation, renal oxygen delivery and consumption, and renal expression of inflammatory and injury markers. Results: We demonstrated that aortic clamping and release resulted in increased oxidative stress and inflammation that was associated with a significant fall in systemic and renal hemodynamics and oxygenation parameters. The treatment of ascorbic acid completely abrogated oxidative stress and inflammatory parameters. However, it only partly improved microcirculatory oxygenation and was without any effect on anuria. Conclusion: The ascorbic acid treatment partly improves microcirculatory oxygenation and prevents oxidative stress without restoring urine output in a severe I/R model of AKI.


1986 ◽  
Vol 251 (2) ◽  
pp. R310-R313 ◽  
Author(s):  
T. R. Schwab ◽  
B. S. Edwards ◽  
D. M. Heublein ◽  
J. C. Burnett

Studies were performed to investigate the role of circulating atrial natriuretic peptide (ANP) in acute volume-expansion natriuresis. Sham-operated (SHAM, n = 6) and right atrial appendectomized (ATRX, n = 12) anesthetized rats underwent acute volume expansion with isoncotic albumin. After equilibration and control periods, volume expansion increased urine flow rate, urinary sodium excretion, fractional excretion of sodium, and circulating ANP. Absolute increases in urine flow rate (delta 46 +/- 4 SHAM; delta 25 +/- 5 microliter/min ATRX), urinary sodium excretion (delta 9.48 +/- 1.01 SHAM; delta 4.77 +/- 1.03 mueq/min ATRX), fractional excretion of sodium (delta 3.16 +/- 0.53 SHAM; delta 1.65 +/- 0.32% ATRX), and ANP (delta 303.3 +/- 35.9 SHAM; delta 156.6 +/- 26.0 pg/ml ATRX) were significantly reduced by right atrial appendectomy. No significant differences in mean arterial pressure, central venous pressure, or glomerular filtration rate during volume expansion were observed between groups. These studies support the hypothesis that right atrial appendectomy in the rat attenuates acute volume expansion-induced increases in circulating ANP and urinary sodium excretion and that the natriuresis of acute volume expansion is mediated in part by an increase in circulating ANP.


1993 ◽  
Vol 264 (3) ◽  
pp. F411-F414 ◽  
Author(s):  
J. A. Haas ◽  
A. A. Khraibi ◽  
M. A. Perrella ◽  
F. G. Knox

Systemic inhibition of nitric oxide synthesis with NG-monomethyl-L-arginine (L-NMMA) increases renal perfusion pressure (RPP) and urinary sodium excretion. Increased RPP has been proposed as one of the mechanisms for the natriuresis caused by intravenous infusion of L-NMMA. We tested the hypothesis that increases in renal interstitial hydrostatic pressure (RIHP) are required for the natriuresis of L-NMMA infusion. Experiments were performed in four groups of Sprague-Dawley rats in which partial aortic clamping and/or bilateral renal decapsulation was performed to control RPP and RIHP. Infusion of L-NMMA (15 mg/kg bolus + 500 micrograms.kg-1 x min-1 continuous infusion) increased RPP (delta+ 14 +/- 1 mmHg), RIHP (delta+ 3.6 +/- 0.7 mmHg), and fractional excretion of sodium (FENa; delta 2.4 +/- 0.6%, P < 0.005). When RPP was prevented from increasing by controlling RPP with an adjustable clamp around the suprarenal aorta, RIHP and FENa did not significantly change. When only RIHP was held constant by bilateral renal decapsulation, FENa was not significantly increased (delta+ 0.68 +/- 0.36%, not significant), despite a significant rise in RPP (delta+ 18 +/- 2 mmHg, P < 0.001). Control of both RPP and RIHP prevented the increase in FENa. Thus, when renal interstitial pressure was controlled, the infusion of L-NMMA did not result in an increase in FENa. These results demonstrate that an increase in RIHP is a necessary component in the natriuresis due to systemic infusion of L-NMMA.


2020 ◽  
Vol 8 (B) ◽  
pp. 262-267
Author(s):  
Walaa Shahin ◽  
Ahmed Bader ◽  
Rawdah Ahmed ◽  
Mona Alattar ◽  
Mona Alfalaki ◽  
...  

BACKGROUND: The risk of acute kidney injury in cystic fibrosis (CF) patients is due to renal tubular affection by CFTR gene. AIM: Our study aimed at early detection of renal impairment in CF patients, to enable careful monitoring and adjustment of nephrotoxic medications. METHODS: Fifty patients with CF were enrolled in our study; they were age- and sex-matched to 40 healthy control children. All subjects were screened by urine analysis, measurements of kidney function tests, fractional excretion of sodium, β2-microglobulin (beta-2-M) excretion, and renal ultrasound examination. Urinary kidney injury molecule-1 (KIM-1) was assayed using ELISA technique. RESULTS: Both urinary beta-2-M and KIM-1 concentrations were significantly higher in CF patients compared to the control group (p < 0.001). The duration of the disease was significantly positively correlated with the urinary beta-2-M and KIM-1 levels (r = 0.6 and 0.7, respectively; p < 0.01). CONCLUSIONS: Our results showed that urinary KIM-1 can be considered as a sensitive early indicator of acute renal injury.


1994 ◽  
Vol 266 (2) ◽  
pp. R578-R583
Author(s):  
Y. Mimura ◽  
F. G. Knox

This study evaluated the effect of acute hypoxia on renal handling of phosphate in rats in the presence and absence of parathyroid hormone (PTH). Hypoxia causes respiratory alkalosis in spontaneously breathing humans and animals. Respiratory alkalosis has been reported to induce a blunted phosphaturic response to PTH. In this study, to avoid the confounding effect of hypocapnia accompanying the hypoxia on phosphate excretion, the rats were ventilated mechanically, and arterial PCO2 levels were controlled. Rats were divided into two main groups depending on the arterial PO2 levels: a hypoxic group (n = 16) and a normoxic group (n = 18). Hypoxia was produced by ventilating with 10% oxygen, and hypocapnia was produced by hyperventilation. In response to PTH, the hypoxic rats without hypocapnia showed a greater increase in fractional excretion of phosphate (FEPi; 37.7 +/- 2.6%, mean +/- SE) compared with normoxic rats (27.4 +/- 2.5%, P < 0.02). During hypocapnia, there was no difference in FEPi between hypoxic and normoxic groups (21.2 +/- 1.5 and 19.5 +/- 1.2%, respectively), and both groups showed a significantly blunted phosphaturic response to PTH compared with normocapnia (P < 0.05 and P < 0.01, respectively). Urinary adenosine 3',5'-cyclic monophosphate (cAMP) increased similarly after PTH infusion between each group. To test whether the phosphaturic effect of PTH in hypoxia and the blunted phosphaturic effect of PTH in hypocapnia are due to steps beyond the generation of cAMP, the phosphaturic response to cAMP infusion was evaluated in 1) hypoxic and normocapnic rats (n = 6), 2) normoxic and normocapnic (control) rats (n = 6), and 3) normoxic and hypocapnic rats (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)


2016 ◽  
Vol 57 (1-2) ◽  
pp. 10-21 ◽  
Author(s):  
Julia Kalenski ◽  
Elina Mancina ◽  
Pascal Paschenda ◽  
Christian Beckers ◽  
Christian Bleilevens ◽  
...  

Background/Aim: The global shortage of donor organs for transplantation has necessitated the expansion of the organ pool through increased use of organs from less ideal donors. Venous systemic oxygen persufflation (VSOP) and oxygenated machine perfusion (OMP) have previously demonstrated beneficial results compared to cold storage (CS) in the preservation of warm-ischemia-damaged kidney grafts. The aim of this study was to compare the efficacy of VSOP and OMP for the preservation of warm-ischemia-damaged porcine kidneys using the recently introduced Ecosol preservation solution compared to CS using Ecosol or histidine-tryptophan-ketoglutarate solution (HTK). Materials and Methods: Kidneys from German Landrace pigs (n = 5/group) were retrieved and washed out with either Ecosol or HTK after 45 min of clamping of the renal pedicle. As controls, kidneys without warm ischemia, cold stored for 24 h in HTK, were employed. Following 24 h of preservation by VSOP, OMP, CS-Ecosol, or CS-HTK, renal function and damage were assessed during 1 h using the isolated perfused porcine kidney model. Results: During reperfusion, urine production was significantly higher in the VSOP and OMP groups than in the CS-HTK group; however, only VSOP could demonstrate lower urine protein concentrations and fractional excretion of sodium, which did not differ from the non-warm-ischemia-damaged control group. VSOP, CS-Ecosol, and controls showed better maintenance of the acid-base balance than CS-HTK. Reduced lipid peroxidation, as reflected in postreperfusion tissue thiobarbituric acid-reactive substance levels, was observed in the VSOP group compared to the OMP group, and the VSOP and CS-Ecosol groups had concentrations similar to the controls. The ratio of reduced to oxidized glutathione was higher in the VSOP, OMP, and CS-Ecosol groups than in the CS-HTK group and controls, with a higher ratio in the VSOP than in the OMP group. Conclusion: VSOP was associated with mitigation of oxidative stress in comparison to OMP and CS. Preservation of warm-ischemia-damaged porcine kidneys by VSOP was improved compared to OMP and CS, and was comparable to preservation of non-warm-ischemia-damaged cold-stored kidneys.


2018 ◽  
Vol 34 (12) ◽  
pp. 2051-2057 ◽  
Author(s):  
Hong Xu ◽  
Ali Hashem ◽  
Anna Witasp ◽  
Rik Mencke ◽  
David Goldsmith ◽  
...  

Abstract Background Recent studies suggest that the phosphaturic hormone fibroblast growth factor 23 (FGF23) is involved in regulation of renal sodium excretion and blood pressure. There is evidence of both direct effects via regulation of the sodium-chloride symporter (NCC) in the distal tubule, and indirect effects through interactions with the renin–angiotensin–aldosterone system. However, clinical data on the association between FGF23 and renal sodium regulation is lacking. Herein, we investigated the associations of FGF23 with renal sodium handling and blood pressure in non-dialysis CKD patients. Methods This was a cross-sectional study encompassing 180 CKD patients Stage 1–5, undergoing renal biopsy. Plasma intact FGF23, 24-h urinary sodium excretion, fractional excretion of sodium (FENa) and blood pressure were measured at baseline. The association between FGF23 and renal sodium handling was explored by multivariate regression analysis. Results The median age was 52.8 years, 60.6% were men and the median estimated glomerular filtration rate (eGFR) was 50.6 mL/min/1.73 m2. In univariate analysis, FGF23 was positively associated with FENa (Spearman’s rho = 0.47; P < 0.001) and systolic blood pressure (rho = 0.17, P < 0.05), but not with plasma sodium, 24-h urinary sodium excretion or mean arterial blood pressure. The association between FGF23 and FENa remained significant after adjustment for potential confounders (multivariable adjusted β coefficient 0.60, P < 0.001). This association was stronger among the 107 individuals with eGFR <60 mL/min/1.73 m2 (β = 0.47, P = 0.04) and in the 73 individuals on any diuretics (β = 0.88, P < 0.001). Adjustment for measured GFR instead of eGFR did not alter the relationship. Conclusions FGF23 is independently associated with increased FENa in non-dialysis CKD patients. These data do not support the notion that FGF23 causes clinically significant sodium retention. Further studies are warranted to explore the mechanism underlying this association.


1998 ◽  
Vol 274 (5) ◽  
pp. F876-F882 ◽  
Author(s):  
So Yeon Chin ◽  
Chi-Tarng Wang ◽  
Dewan S. A. Majid ◽  
L. Gabriel Navar

Experiments were performed in anesthetized male Sprague-Dawley rats to determine whether increased nitric oxide (NO) activity during the development of hypertension exerts a protective effect on renal cortical blood flow (CBF) and medullary blood flow (MBF). The effects of acute NO synthase inhibition on renal function and on CBF and MBF, measured by laser-Doppler flow probes, were evaluated in control and ANG II-infused hypertensive rats, prepared by the infusion of ANG II at a rate of 65 ng/min via osmotic minipumps implanted subcutaneously for 13 days. In normotensive rats ( n = 8), intravenous infusion of N ω-nitro-l-arginine (NLA; 20 μg ⋅ 100 g−1 ⋅ min−1) decreased CBF by 21 ± 4% and MBF by 49 ± 8% and increased blood pressure from 118 ± 1 to 140 ± 2 mmHg. In ANG II-infused rats ( n = 7), CBF and MBF decreased by 46 ± 5% and 25 ± 6%, respectively, during infusion of NLA. Arterial pressure increased from 160 ± 5 to 197 ± 7 mmHg, which was a greater absolute increase than in normotensive controls. Basal renal blood flow (RBF), estimated from p-aminohippurate clearance and hematocrit, was similar in both the control (6.0 ± 0.5 ml ⋅ min−1 ⋅ g−1) and hypertensive (6.0 ± 0.6 ml ⋅ min−1 ⋅ g−1) rats. However, NLA-induced reductions in RBF averaged 60 ± 5% in the hypertensive rats, compared with 31 ± 9% observed in control rats. GFR in control (0.97 ± 0.03 ml ⋅ min−1 ⋅ g−1) and hypertensive rats (0.78 ± 0.12 ml ⋅ min−1 ⋅ g−1) decreased to a similar extent during the first 30-min period of NLA infusion. GFR returned toward control levels in control rats; in contrast, GFR remained significantly decreased in the ANG II-infused rats (0.58 ± 0.11 ml ⋅ min−1 ⋅ g−1). Basal urinary sodium excretion (0.2 ± 0.08 μeq ⋅ min−1 ⋅ g−1), fractional excretion of sodium (0.3 ± 0.13%), and urine flow (4.9 ± 0.39 μl ⋅ min−1 ⋅ g−1) in hypertensive rats did not increase significantly after NLA treatment as occurred in normotensive controls. These data suggest that a compensatory increase in nitric oxide activity partially counteracts the vasoconstrictor influence of elevated ANG II levels to regulate renal hemodynamics and maintain cortical perfusion in the renal circulation.


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