Document Detail


PKC-alpha mediates flow-stimulated superoxide production in thick ascending limbs.
MedLine Citation:
PMID:  20053794     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We showed that luminal flow increases net superoxide (O(2)(-)) production via NADPH oxidase in thick ascending limbs. Protein kinase C (PKC) activates NADPH oxidase activity in phagocytes, cardiomyocytes, aortic endothelial cells, vascular smooth muscle cells, and renal mesangial cells. However, the flow-activated pathway that induces NADPH oxidase activity in thick ascending limbs is unclear. We hypothesized that PKC mediates flow-stimulated net O(2)(-) production by thick ascending limbs. Initiation of flow (20 nl/min) increased net O(2)(-) production from 4 +/- 1 to 61 +/- 12 AU/s (P < 0.007; n = 5). The NADPH oxidase inhibitor apocynin completely blocked the flow-induced increase in net O(2)(-) production (2 +/- 1 vs. 1 +/- 1 AU/s; P > 0.05; n = 5). Flow-stimulated O(2)(-) was also blocked in p47(phox)-deficient mice. We measured flow-stimulated PKC activity with a fluorescence resonance energy transfer (FRET)-based membrane-targeted PKC activity reporter and found that the FRET ratio increased from 0.87 +/- 0.02 to 0.96 +/- 0.04 AU (P < 0.05; n = 6). In the absence of flow, the PKC activator phorbol 12-myristate 13-acetate (200 nM) enhanced net O(2)(-) production from 5 +/- 2 to 92 +/- 6 AU/s (P < 0.001; n = 6). The PKC-alpha- and betaI-selective inhibitor Gö 6976 (100 nM) decreased flow-stimulated net O(2)(-) production from 54 +/- 15 to 2 +/- 1 AU/s (P < 0.04; n = 5). Flow-induced net O(2)(-) production was inhibited in thick ascending limbs transduced with dominant-negative (dn)PKC-alpha but not dnPKCbetaI or LacZ (Delta = 11 +/- 3 AU/s for dnPKCalpha, 55 +/- 7 AU/s for dnPKCbetaI, and 63 +/- 7 AU/s for LacZ; P < 0.001; n = 6). We concluded that flow stimulates net O(2)(-) production in thick ascending limbs via PKC-alpha-mediated activation of NADPH oxidase.
Authors:
Nancy J Hong; Guillermo B Silva; Jeffrey L Garvin
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-01-06
Journal Detail:
Title:  American journal of physiology. Renal physiology     Volume:  298     ISSN:  1522-1466     ISO Abbreviation:  Am. J. Physiol. Renal Physiol.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-23     Completed Date:  2010-04-22     Revised Date:  2011-07-27    
Medline Journal Info:
Nlm Unique ID:  100901990     Medline TA:  Am J Physiol Renal Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  F885-91     Citation Subset:  IM    
Affiliation:
Department of Internal Medicine, Hypertension and Vascular Research Division, Henry Ford Hospital, 2799 West Grand Blvd., Detroit, MI 48202, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Gene Expression Regulation, Enzymologic
Isoenzymes
Kidney Medulla / metabolism
Loop of Henle / metabolism*
Male
Mice
Mice, Inbred C57BL
NADPH Oxidase / genetics,  metabolism
Protein Kinase C / genetics,  metabolism
Protein Kinase C-alpha / metabolism*
Rats
Rats, Sprague-Dawley
Superoxides / metabolism*
Grant Support
ID/Acronym/Agency:
HL-28982/HL/NHLBI NIH HHS; HL-70985/HL/NHLBI NIH HHS; HL-90550/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Isoenzymes; 11062-77-4/Superoxides; EC 1.6.3.1/NADPH Oxidase; EC 1.6.3.1/neutrophil cytosolic factor 1; EC 2.7.1.-/protein kinase C beta; EC 2.7.11.13/Protein Kinase C; EC 2.7.11.13/Protein Kinase C-alpha
Comments/Corrections
Comment In:
Am J Physiol Renal Physiol. 2010 Apr;298(4):F883-4   [PMID:  20130124 ]

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