Document Detail

L-type Ca2+ channel and Na+/Ca2+ exchange inhibitors reduce Ca2+ accumulation in reperfused skeletal muscle.
MedLine Citation:
PMID:  8926255     Owner:  NLM     Status:  MEDLINE    
It is known that extracellular Ca2+ accumulates within skeletal muscle after prolonged periods of ischemia and reperfusion. In this study, we determined whether the L-type Ca2+ channel and the Na+/Ca2+ exchanger mediated Ca2+ influx and whether Ca2+ accumulation limited the metabolic and contractile recovery of reperfused skeletal muscle. Contracting rat hindlimbs (1-Hz twitch) exposed to 40 min of no-flow ischemia were reperfused with diltiazem (500 microM) or 3,4-dichlorobenzamil (300 microM) to block the Na+/Ca2+ exchanger and/or the L-type Ca2+ channel. High inhibitor concentrations were used to counter the binding of diltiazem and 3,4-dichlorobenzamil to albumin and red blood cells. Muscle Ca2+ accumulation, contractile function, and energy metabolism were assessed by measuring intracellular Ca2+ concentration ([Ca2+]i), Ca2+ influx, twitch tension, and high-energy phosphagens [ATP, total adenine nucleotides (TAN) and phosphocreatine (PCr)]. Compared with control reperfusion, diltiazem and 3,4-dichlorobenzamil reduced Ca2+ influx and attenuated the rise in [Ca2+]i in the fast-oxidative glycolytic plantaris (Pl) and the fast-glycolytic white gastrocnemius (WG). The inhibitor-induced decrease in Ca2+ influx was 1.5- to 2-fold greater with 3,4-dichlorobenzamil than with diltiazem. Coinciding with the reduced Ca2+ accumulation, diltiazem and 3,4-dichlorobenzamil enhanced the resynthesis of ATP (Pl and WG), PCr (Pl and WG), and TAN (Pl) compared with control reperfusion. 3,4-Dichlorobenzamil also augmented twitch-tension recovery. We conclude that Ca2+ accumulation during reperfusion 1) arises from L-type Ca2+ channel and Na+/Ca2+ exchange activation; and 2) impairs the metabolic and contractile recovery of skeletal muscle.
D G Welsh; M I Lindinger
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  80     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 Apr 
Date Detail:
Created Date:  1996-11-27     Completed Date:  1996-11-27     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1263-9     Citation Subset:  IM    
Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada.
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MeSH Terms
Adenosine Triphosphate / metabolism
Calcium / metabolism*
Calcium Channel Blockers / pharmacology*
Calcium Channels / drug effects*
Ion Transport / drug effects*
Muscle, Skeletal / drug effects*
Rats, Sprague-Dawley
Sodium / metabolism
Reg. No./Substance:
0/Calcium Channel Blockers; 0/Calcium Channels; 56-65-5/Adenosine Triphosphate; 7440-23-5/Sodium; 7440-70-2/Calcium

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