Document Detail


Luminal flow regulates NO and O2(-) along the nephron.
MedLine Citation:
PMID:  21345976     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Urinary flow is not constant but in fact highly variable, altering the mechanical forces (shear stress, stretch, and pressure) exerted on the epithelial cells of the nephron as well as solute delivery. Nitric oxide (NO) and superoxide (O(2)(-)) play important roles in various processes within the kidney. Reductions in NO and increases in O(2)(-) lead to abnormal NaCl and water absorption and hypertension. In the last few years, luminal flow has been shown to be a regulator of NO and O(2)(-) production along the nephron. Increases in luminal flow enhance fluid, Na, and bicarbonate transport in the proximal tubule. However, we know of no reports directly addressing flow regulation of NO and O(2)(-) in this segment. In the thick ascending limb, flow-stimulated NO and O(2)(-) formation has been extensively studied. Luminal flow stimulates NO production by nitric oxide synthase type 3 and its translocation to the apical membrane in medullary thick ascending limbs. These effects are mediated by flow-induced shear stress. In contrast, flow-induced stretch and NaCl delivery stimulate O(2)(-) production by NADPH oxidase in this segment. The interaction between flow-induced NO and O(2)(-) is complex and involves more than one simply scavenging the other. Flow-induced NO prevents flow from increasing O(2)(-) production via cGMP-dependent protein kinase in thick ascending limbs. In macula densa cells, shear stress increases NO production and this requires that the primary cilia be intact. The role of luminal flow in NO and O(2)(-) production in the distal tubule is not known. In cultured inner medullary collecting duct cells, shear stress enhances nitrite accumulation, a measure of NO production. Although much progress has been made on this subject in the last few years, there are still many unanswered questions.
Authors:
Pablo D Cabral; Jeffrey L Garvin
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Review     Date:  2011-02-23
Journal Detail:
Title:  American journal of physiology. Renal physiology     Volume:  300     ISSN:  1522-1466     ISO Abbreviation:  Am. J. Physiol. Renal Physiol.     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-05-05     Completed Date:  2011-07-01     Revised Date:  2012-05-01    
Medline Journal Info:
Nlm Unique ID:  100901990     Medline TA:  Am J Physiol Renal Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  F1047-53     Citation Subset:  IM    
Affiliation:
Hypertension and Vascular Research Div., Dept. of Internal Medicine, Henry Ford Hospital, Detroit, MI 48202, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Humans
Mechanotransduction, Cellular*
NADPH Oxidase / metabolism
Nephrons / metabolism*
Nitric Oxide / metabolism*
Nitric Oxide Synthase Type III / metabolism
Pressure
Sodium Chloride, Dietary / metabolism
Stress, Mechanical
Superoxides / metabolism*
Urodynamics*
Grant Support
ID/Acronym/Agency:
HL 028982/HL/NHLBI NIH HHS; HL 070985/HL/NHLBI NIH HHS; HL 090550/HL/NHLBI NIH HHS; R01 HL070985-10/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Sodium Chloride, Dietary; 10102-43-9/Nitric Oxide; 11062-77-4/Superoxides; EC 1.14.13.39/Nitric Oxide Synthase Type III; EC 1.6.3.1/NADPH Oxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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