Document Detail

Neuronal nitric oxide synthase modulates rat renal microvascular function.
MedLine Citation:
PMID:  9530268     Owner:  NLM     Status:  MEDLINE    
This study was performed to determine the influence of neuronal nitric oxide synthase (nNOS) on renal arteriolar tone under conditions of normal, interrupted, and increased volume delivery to the macula densa segment and on the microvascular responses to angiotensin II (ANG II). Experiments were performed in vitro on afferent (21.2 +/- 0.2 microns) and efferent (18.5 +/- 0.2 microns) arterioles of kidneys harvested from male Sprague-Dawley rats, using the blood-perfused juxtamedullary nephron technique. Superfusion with the specific nNOS inhibitor, S-methyl-L-thiocitrulline (L-SMTC), decreased afferent and efferent arteriolar diameters, and these decreases in arteriolar diameters were prevented by interruption of distal volume delivery by papillectomy. When 10 mM acetazolamide was added to the blood perfusate to increase volume delivery to the macula densa segment, afferent arteriolar vasoconstrictor responses to L-SMTC were enhanced, but this effect was again completely prevented after papillectomy. In contrast, the arteriolar diameter responses to the nonselective NOS inhibitor, N omega-nitro-L-arginine (L-NNA) were only attenuated by papillectomy. L-SMTC (10 microM) enhanced the efferent arteriolar vasoconstrictor response to ANG II but did not alter the afferent arteriolar vasoconstrictor responsiveness to ANG II. In contrast, L-NNA (100 microM) enhanced both afferent and efferent arteriolar vasoconstrictor responses to ANG II. These results indicate that the modulating influence of nNOS on afferent arteriolar tone of juxtamedullary nephrons is dependent on distal tubular fluid flow. Furthermore, nNOS exerts a differential modulatory action on the juxtamedullary micro-vasculature by enhancing efferent, but not afferent, arteriolar responsiveness to ANG II.
A Ichihara; E W Inscho; J D Imig; L G Navar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  274     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1998 Mar 
Date Detail:
Created Date:  1998-04-14     Completed Date:  1998-04-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  F516-24     Citation Subset:  IM    
Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112-2699, USA.
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MeSH Terms
Acetazolamide / pharmacology
Acetylcholine / pharmacology
Angiotensin II / pharmacology
Arterioles / physiology*
Citrulline / analogs & derivatives,  pharmacology
Enzyme Inhibitors / pharmacology
Kidney / blood supply*
Kidney Tubules, Distal / blood supply,  innervation
Neurons / enzymology*
Nitric Oxide Synthase / antagonists & inhibitors,  physiology*
Rats, Sprague-Dawley
Thiourea / analogs & derivatives,  pharmacology
Vasomotor System / physiology
Video Recording
Grant Support
Reg. No./Substance:
0/Enzyme Inhibitors; 11128-99-7/Angiotensin II; 156719-41-4/S-methylthiocitrulline; 372-75-8/Citrulline; 51-84-3/Acetylcholine; 59-66-5/Acetazolamide; 62-56-6/Thiourea; EC Oxide Synthase

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