scholarly journals Nitric oxide inhibits sodium reabsorption in the isolated perfused cortical collecting duct.

1995 ◽  
Vol 6 (1) ◽  
pp. 89-94
Author(s):  
B A Stoos ◽  
N H Garcia ◽  
J L Garvin

Indirect evidence suggests that nitric oxide inhibits sodium reabsorption by the collecting duct; however, direct evidence is lacking. It was hypothesized that endothelium-derived nitric oxide inhibits sodium flux in the cortical collecting duct by blocking amiloride-sensitive sodium channels. Tubules were obtained from Sprague-Dawley rats pretreated with deoxycorticosterone acetate (5 mg/rat i.m.) 5 to 9 days before the experiment. Nitric oxide was added to the system by either the addition of endothelial cells and the induction of the release of nitric oxide via acetylcholine (10(-7) M) or by the addition of nitric oxide donors. Acetylcholine-induced nitric oxide release from endothelial cells decreased lumen-to-bath sodium flux by 24 +/- 7% (N = 3; P < 0.05). The addition of the nitric oxide donor, spermine NONOate (10(-5) M), decreased net sodium flux 68% from 10.1 +/- 2.0 to 3.6 +/- 2 pmol/mm.min (N = 5; P < 0.025). To assure that the inhibition of sodium flux was due to nitric oxide, another donor, nitroglycerin (2 x 10(-5) M), was used, which decreased sodium flux by 43%. Luminal amiloride (10 microM) decreased net sodium flux by 83% (from 14.8 +/- 1.2 to 2.4 +/- 0.7 pmol/mm.min; N = 5; P < 0.025). The addition of nitric oxide via spermine NONOate to tubules decreased intracellular sodium levels by 26% (N = 6; P < 0.005). The Na(+)-K+ATPase activity of spermine NONOate-treated tubules was 14.7 +/- 3.2 pmol/mm.min compared with the control value of 10.2 +/- 2.0 pmol/mm.min. Nitroglycerin did not significantly affect pump activity either.(ABSTRACT TRUNCATED AT 250 WORDS)

1996 ◽  
Vol 270 (1) ◽  
pp. F206-F210 ◽  
Author(s):  
N. H. Garcia ◽  
S. I. Pomposiello ◽  
J. L. Garvin

Nitric oxide (NO) reduces blood pressure in vivo by two mechanisms, vasodilation and increasing urinary volume: however, the exact mechanism by which it increases urinary volume is not clear. We hypothesized that NO inhibits antidiuretic hormone (ADH)-stimulated fluid reabsorption (J(r)) by the isolated rat cortical collecting duct (CCD) by decreasing water permeability (Pf) and sodium reabsorption (Jna). In the presence of 10(-11) MADH, Jv was 0.15 +/- 0.04 nl.min-1.mm-1; after 10(-6) M spermine nonoate (SPM) was added to the bath. Jv decreased to 0.06 +/- 0.03 nl.min-1.mm-1 (P < 0.03). To investigate whether the inhibition of Jv was the result of decreased Pf and/or Jna, we first tested the effect of SPM on ADH-stimulated Pf. Basal Pf was stimulated to 289.2 +/- 77.3 microns/s after 10(-11) M ADH was added to the bath (P < 0.01). SPM decreased Pf to 159.8 +/- 45.0 microns/s (P < 0.05). To ensure that this effect on Pf was due to NO release, we used another NO donor, nitroglycerin (NTG). Pf was initially -25.8 +/- 18.3 microns/s and increased to 133.9 +/- 30.5 microns/s after addition of 10(-11) M ADH (P < 0.002). NTG, 20 microM, lowered Pf to 92.4 +/- 18.4 microns/s (P < 0.02). In the presence of 10(-9) M ADH, NTG also decreased Pf(P < 0.04). Next we investigated the effect of SPM on ADH-stimulated JNa. In the presence of ADH, JNa was 37.8 +/- 7.3 pmol.min-1.mm-1. After SPM was added, it dropped to 24.3 +/- 5.1 pmol.min-1.mm-1 (P < 0.05). Time controls exhibited no change in ADH-stimulated Jv, Pf, or Jna. We concluded that 1) NO decreases ADH-stimulated water and sodium transport in the isolate CCD, and 2) water reabsorption is inhibited by a primary effect on Pf. A direct effect of NO on the CCD may explain its natriuretic and diuretic effects observed in vivo.


2006 ◽  
Vol 290 (5) ◽  
pp. F1055-F1064 ◽  
Author(s):  
Jian Song ◽  
Xinqun Hu ◽  
Shahla Riazi ◽  
Swasti Tiwari ◽  
James B. Wade ◽  
...  

Hyperinsulinemia is associated with hypertension. Dysregulation of renal distal tubule sodium reabsorption may play a role. We evaluated the regulation of the epithelial sodium channel (ENaC) and the thiazide-sensitive Na-Cl cotransporter (NCC) during chronic hyperinsulinemia in rats and correlated these changes to blood pressure as determined by radiotelemetry. Male Sprague-Dawley rats (∼270 g) underwent one of the following three treatments for 4 wk ( n = 6/group): 1) control; 2) insulin-infused plus 20% dextrose in drinking water; or 3) glucose water-drinking (20% dextrose in water). Mean arterial pressures were increased by insulin and glucose (mmHg at 3 wk): 98 ± 1 (control), 107 ± 2 (insulin), and 109 ± 3 (glucose), P < 0.01. Insulin (but not glucose) increased natriuretic response to benzamil (ENaC inhibitor) and hydrochlorothiazide (NCC inhibitor) on average by 125 and 60%, respectively, relative to control rats, suggesting increased activity of these reabsorptive pathways. Neither insulin nor glucose affected the renal protein abundances of NCC or the ENaC subunits (α, β, and γ) in kidney cortex, outer medulla, or inner medulla in a major way, as determined by immunoblotting. However, insulin and to some extent glucose increased apical localization of these subunits in cortical collecting duct principal cells, as determined by immunoperoxidase labeling. In addition, insulin decreased cortical “with no lysine” kinase (WNK4) abundance (by 16% relative to control), which may have increased NCC activity. Overall, insulin infusion increased blood pressure, and NCC and ENaC activity in rats. Increased apical targeting of ENaC and decreased WNK4 expression may be involved.


Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Brandon A Kemp ◽  
Nancy L Howell ◽  
John J Gildea ◽  
Susanna R Keller ◽  
Shetal H Padia

Intrarenal ghrelin infusion stimulates distal nephron-dependent sodium (Na+) reabsorption in normal rats, but the mechanism is unknown. The main Na+ transporters of the distal nephron segment are the Na+-Cl- co-transporter (NCC) and the epithelial Na+ channel (ENaC). To determine which of these transporters is involved in the antinatriuretic actions of intrarenal ghrelin receptors, uninephrectomized Sprague-Dawley rats received 3 cumulative 1h renal interstitial (RI) infusions of ghrelin (0.3-3 μg/min, N=8) or vehicle (5% dextrose in water, D5W, N=8), prior to harvesting the infused kidney for determination of NCC and ENaC protein expression. Ghrelin-infused rats demonstrated significantly reduced Na+ excretion rates (UNaV) compared to D5W-infused rats (66.7±7.1% of baseline, P<0.01) and significantly increased cortical collecting duct ENaC expression (2.46±0.17 and 1.56±0.19 densitometric units respectively, P<0.01). Renal NCC expression did not change in response to either ghrelin or D5W infusion (4.21±0.58 and 4.13±0.44 densitometric units respectively, P=NS). To test whether the ghrelin-induced increase in collecting duct ENaC expression was responsible for the antinatriuretic actions of ghrelin, we infused ghrelin into the kidney in the presence of amiloride, a selective inhibitor of ENaC activity. Following uninephrectomy, rats were implanted with either a subcutaneous osmotic minipump which systemically delivered amiloride (1.4 ng/min) for 72h to block ENaC activity (N=6), or a minipump that was filled with D5W (N=6). On the day of the study, RI ghrelin (0.3-3 μg/min) or D5W infusion was initiated. RI ghrelin infusion (in the absence of amiloride) significantly reduced UNaV to 58.9±7.2% of baseline, P<0.01; however, in the presence of amiloride, RI ghrelin failed to reduce UNaV, demonstrating values identical to rats that did not receive RI ghrelin. In contrast, studies carried out in the presence of chlorothiazide pumps (to block NCC activity, 1.1 μg/min, N=6), continued to demonstrate ghrelin-induced antinatriuresis (UNaV decreased to 65.3±8.8% of baseline, P<0.01). Mean arterial pressures did not change during any of the acute RI infusions. Thus, intact ENaC function is necessary for ghrelin-induced Na+ reabsorption.


2007 ◽  
Vol 292 (2) ◽  
pp. H893-H903 ◽  
Author(s):  
Galina N. Antonova ◽  
Connie M. Snead ◽  
Alexander S. Antonov ◽  
Christiana Dimitropoulou ◽  
Richard C. Venema ◽  
...  

Large (pathological) amounts of nitric oxide (NO) induce cell injury, whereas low (physiological) NO concentrations often ameliorate cell injury. We tested the hypotheses that pretreatment of endothelial cells with low concentrations of NO (preconditioning) would prevent injury induced by high NO concentrations. Apoptosis, induced in bovine aortic endothelial cells (BAECs) by exposing them to either 4 mM sodium nitroprusside (SNP) or 0.5 mM N-(2-aminoethyl)- N-(2-hydroxy-2-nitrosohydrazino)-1,2-ethylenediamine (spermine NONOate) for 8 h, was abolished by 24-h pretreatment with either 100 μM SNP, 10 μM spermine NONOate, or 100 μM 8-bromo-cGMP (8-Br-cGMP). Repair of BAECs following wounding, measured as the recovery rate of transendothelial electrical resistance, was delayed by 8-h exposure to 4 mM SNP, and this delay was significantly attenuated by 24-h pretreatment with 100 μM SNP. NO preconditioning produced increased association and expression of soluble guanyl cyclase (sGC) and heat shock protein 90 (HSP90). The protective effect of NO preconditioning, but not the injurious effect of 4 mM SNP, was abolished by either a sGC activity inhibitor 1H-[1,2,4]oxadiazolo-[4,3- a]quinoxalin-1-one (ODQ) or a HSP90 binding inhibitor (radicicol) and was mimicked by 8-Br-cGMP. We conclude that preconditioning with a low dose of NO donor accelerates repair and maintains endothelial integrity via a mechanism that includes the HSP90/sGC pathway. HSP90/sGC may thus play a role in the protective effects of NO-generating drugs from injurious stimuli.


Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Casandra M Monzon ◽  
Jeffrey Garvin

About 50% of the Na reabsorbed in thick ascending limbs (TALs) traverses the paracellular pathway. The ionic selectivity of this route is regulated by claudins in the tight junctions. TALs express claudin-19 which has been reported to regulate TAL Na permeability. We showed that nitric oxide (NO) decreases Na/Cl permeability ratio (PNa/PCl) in TALs by increasing the absolute permeabilities of both ions though PCl increased more. However, whether NO affects paracellular permeability via claudin-19 is unknown. We hypothesize that NO regulates the paracellular permselectivity in TALs through this claudin. To test this we perfused TALs from Sprague Dawley rats and measured dilution potentials (a measure of permselectivity) with and without exogenously-added or endogenously-produced NO in the presence or absence of an antibody against an extracellular domain of claudin-19 or Tamm-Horsfall protein (control). Dilution potentials were generated by reducing bath NaCl from 141 to 32 mM. For the NO donor spermine NONOate (SPM): during the control period, the dilution potential was -9.3 ± 1.8 mV. After SPM (200 μM), it was -6.7 ± 1.6 mV (n = 6; p < 0.003). In the presence of the claudin-19 antibody, SPM had no significant effect on dilution potentials (claudin-19 antibody alone: -12.7 ± 2.1 mV vs claudin-19 antibody + SPM: -12.9 ± 2.4 mV; n = 6). The claudin-19 antibody alone had no effect on dilution potentials. In the presence of the Tamm-Horsfall protein, the effect of SPM was still present (Tamm-Horsfall protein antibody alone: -9.7 ± 1.0 mV; Tamm-Horsfall protein antibody + SPM: -6.3 ± 1.1 mV, p<0.006, n = 6). For experiments with endogenously-produced NO, L-arginine the substrate for NO synthase was added. During the control period, the dilution potential was -11.0 ± 1.1 mV. After L-arginine (500 μM) treatment, they were -9.0 ± 1.2 mV (n = 9; p < 0.05). In the presence of the claudin-19 antibody, L-arginine had no significant effect on dilution potentials (claudin-19 antibody alone: -10.1 ± 0.9 mV vs claudin-19 antibody + L-arginine: -10.1 ± 1.0 mV; n = 9). In the presence of the Tamm-Horsfall protein, the effect of L-arginine was still present. We conclude that the actions of NO on the paracellular permselectivity in thick ascending limbs are at least in part mediated by claudin-19.


2009 ◽  
Vol 297 (6) ◽  
pp. F1606-F1613 ◽  
Author(s):  
Libor Kopkan ◽  
Md Abdul H. Khan ◽  
Agnieszka Lis ◽  
Mouhamed S. Awayda ◽  
Dewan S. A. Majid

Although hypercholesterolemia is implicated in the pathophysiology of many renal disorders as well as hypertension, its direct actions in the kidney are not yet clearly understood. In the present study, we evaluated renal responses to administration of cholesterol (8 μg·min−1·100 g body wt−1; bound by polyethylene glycol) into the renal artery of anesthetized male Sprague-Dawley rats. Total renal blood flow (RBF) was measured by a Transonic flow probe, and glomerular filtration rate (GFR) was determined by Inulin clearance. In control rats ( n = 8), cholesterol induced reductions of 10 ± 2% in RBF [baseline (b) 7.6 ± 0.3 μg·min−1·100 g−1], 17 ± 3% in urine flow (b, 10.6 ± 0.9 μg·min−1·100 g−1), 29 ± 3% in sodium excretion (b, 0.96 ± 0.05 μmol·min−1·100 g−1) and 24 ± 2% in nitrite/nitrate excretion (b, 0.22 ± 0.01 nmol·min−1·100 g−1) without an appreciable change in GFR (b, 0.87 ± 0.03 ml·min−1·100 g−1). These renal vasoconstrictor and anti-natriuretic responses to cholesterol were absent in rats pretreated with nitric oxide (NO) synthase inhibitor, nitro-l-arginine methylester (0.5 μg·min−1·100 g−1; n = 6). In rats pretreated with superoxide (O2−) scavenger tempol (50 μg·min−1·100 g−1; n = 6), the cholesterol-induced renal responses remained mostly unchanged, although there was a slight attenuation in anti-natriuretic response. This anti-natriuretic response to cholesterol was abolished in furosemide-pretreated rats (0.3 μg·min−1·100 g−1; n = 6) but remained unchanged in amiloride-pretreated rats (0.2 μg·min−1·100 g−1; n = 5), indicating that Na+/K+/2Cl− cotransport is the dominant mediator of this effect. These data demonstrate that cholesterol-induced acute renal vasoconstrictor and antinatriuretic responses are mediated by a decrease in NO production. These data also indicate that tubular effect of cholesterol on sodium reabsorption is mediated by the furosemide sensitive Na+/K+/2Cl− cotransporter.


1990 ◽  
Vol 258 (5) ◽  
pp. F1320-F1327 ◽  
Author(s):  
H. Kimura ◽  
S. K. Mujais

The present study examined the alterations in the cortical collecting tubule (CCT) Na-K pump that occur after unilateral ureteral obstruction and their consequences on electrolyte excretion. In male Sprague-Dawley rats, unilateral ureteral ligation led to a progressive decrease in intact CCT Na-K pump in situ turnover worsening with the duration of the obstruction: control, 20.1 +/- 0.4; obstructed kidney: 3 h, 14.6 +/- 0.3; 12 h, 12.7 +/- 0.6; 24 h, 12.8 +/- 0.5; 48 h, 11.6 +/- 0.5; and 96 h, 10.6 +/- 0.4 pmol Rb.mm-1.min-1 (all P less than 0.001 vs. control). CCT diameter increased with the duration of obstruction. Release of ureteral obstruction was associated with restitution of pump turnover rate. With 3 h of obstruction, recovery of pump in situ turnover was complete (19.7 +/- 0.4 pmol Rb.mm-1.min-1) by 24 h after release. With more prolonged obstruction (24 h) recovery was partial by 24 h postrelease (16.2 +/- 0.5 pmol Rb.mm-1.min-1) and complete (19.8 +/- 0.7 pmol Rb.mm-1.min-1) by 48 h, suggesting a delay in recovery without the occurrence of irreversible damage. The impairment in Na-K pump in situ turnover was paralleled by an impairment in the ability of the obstructed kidney to excrete an acute potassium load. This parallelism of functional and biochemical studies favors the notion that impairment of CCT Na-K pump in situ turnover contributes significantly to the abnormal potassium excretion that accompanies obstructive damage.


1994 ◽  
Vol 267 (2) ◽  
pp. F325-F330 ◽  
Author(s):  
T. Yang ◽  
Y. Terada ◽  
H. Nonoguchi ◽  
M. Tsujino ◽  
K. Tomita ◽  
...  

We investigated kallikrein-binding protein (KBP) mRNA distribution in the kidney of Sprague-Dawley (SD) rats, spontaneously hypertensive rats (SHR), and Wistar-Kyoto strain (WKY) rats. Northern blot analysis revealed that KBP mRNA was located mainly in the medulla and with lower amounts in SHR than in WKY rats. KBP mRNA in microdissected nephron segments was detected by reverse transcription and polymerase chain reaction (RT-PCR) followed by Southern blot analysis. In SD rats, the most abundant signals were consistently found in inner medullary collecting duct (IMCD), with small amounts in outer medullary collecting duct, proximal convoluted tubule, and glomerulus. No signals were found in connecting tubule and cortical collecting duct. The nephron distribution of KBP mRNA was similar in WKY and SD rats. Only a small amount of signal was found, however, in IMCD of SHR. In conclusion, 1) KBP mRNA was predominantly distributed in the medullary segments of the distal nephron, downstream from the known kallikrein activity site in the collecting duct, and 2) KBP mRNA expression was significantly decreased in the kidney of SHR.


1997 ◽  
Vol 73 ◽  
pp. 164
Author(s):  
Naoko Mrtsuiomi ◽  
Yasuo Matsummura ◽  
Chitose Atashi ◽  
Masanori Takaoka ◽  
Shiro Morimoto

1996 ◽  
Vol 271 (1) ◽  
pp. G27-G35
Author(s):  
J. G. Wood ◽  
Q. Zhang ◽  
Z. Y. Yan ◽  
L. Y. Cheung

We previously observed that endothelin-1 (ET-1)-induced gastric vasoconstriction is enhanced after ischemia-reperfusion. The purpose of our present study was to examine the role of nitric oxide in regulating ET-1-induced vasoconstriction under normal conditions and after ischemia-reperfusion. Using a mechanically perfused stomach segment from chloralose-anesthetized dogs, we examined 1) responses to NG-nitro-L-arginine methyl ester (L-NAME) alone and in combination with L-arginine, 2) whether L-NAME affects ET-1-induced vasoconstriction under normal conditions and after ischemia-reperfusion, and 3) if spermine NONOate inverted question mark1,3-propanediamine-N-[4-1-(3-aminopropyl)-2-hydroxy-2-nitrosohydrazi no] butyl; a nitric oxide donor inverted question mark attenuates the augmented response to ET-1 after ischemia-reperfusion. Our results show that 1) L-NAME significantly increased baseline vascular resistance and this response was reduced by L-arginine, 2) ET-1-induced vasoconstriction was enhanced by L-NAME, and 3) administration of spermine NONOate during reperfusion largely attenuated the vasoconstrictor response to ET-1 after ischemia-reperfusion. Our findings are consistent with the hypothesis that nitric oxide modulates responses to ET-1 under normal conditions, and loss of this vasodilator after ischemia-reperfusion results in an augmented response to ET-1.


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