Document Detail

Glucagon-induced changes in the action potential, contraction, and Na+-K+-ATPase of cardiac muscle.
MedLine Citation:
PMID:  126113     Owner:  NLM     Status:  MEDLINE    
The effects of glucagon in concentrations of 0.294 times 10(-6) mol/l, 1.47 times 10(-6) mol/l; 2.94 times 10(-6) mol/l, 5.8 times 10(-6) mol/l, and 1.47 times 10(-5) mol/l on the simultaneously recorded action potentials and contractions; and microsomal and sarcolemmal Na+-tk+-atpase in the myocardium of the guinea pig, rabbit, dog, and pig were investigated. Glucagon in all the concentrations produced an inhibition of the Na+-K+-ATPase associated with an increase in the contractility and shortening of the duration of action potential in dog myocardium. The increase in contraction was concentration-dependent up to a certain concentration. Inhibition of sarcolemmal ATPase was more than that of microsomal ATPase. In none of the concentrations did glucagon produce any significant changes in the Na+-K+-ATPase. In none of the concentrations did glucagon produce any significant changes in the Na+-K+-ATPase, contractility, and action potential duration in the myocardium of guinea pig, rabbit, or pig. These results suggest that glucagon-induced positive inotropic effect might be due to an increase in the Ca++ influx as a result of inhibition of membrane Na+-K+-ATPase. Shortening of the action potential duration might also be due to an increased efflux of potassium as a result of an inhibition of Na+-K+-ATPase.
K Prasad
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article    
Journal Detail:
Title:  Cardiovascular research     Volume:  9     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1975 May 
Date Detail:
Created Date:  1975-12-18     Completed Date:  1975-12-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  355-65     Citation Subset:  IM    
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MeSH Terms
Action Potentials / drug effects*
Adenosine Triphosphatases / metabolism*
Dose-Response Relationship, Drug
Glucagon / pharmacology*
Guinea Pigs
Heart / drug effects*
Microsomes / enzymology
Myocardial Contraction / drug effects*
Myocardium / enzymology*
Papillary Muscles / drug effects
Sarcolemma / enzymology
Reg. No./Substance:
7440-09-7/Potassium; 7440-23-5/Sodium; 7440-70-2/Calcium; 9007-92-5/Glucagon; EC 3.6.1.-/Adenosine Triphosphatases

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

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