Epinephrine-induced automaticity of canine cardiac Purkinje fibers and its relationship to the adenylate cyclase-adenosine 3',5'-monophosphate system
We studied the relationship between epinephrine-induced increases in automaticity and in the adenylate cyclase-adenosine 3',5'-monophosphate (cAMP) system in canine cardiac Purkinje fibers. In intact Purkinje fiber bundles superfused with Tyrode's solution, epinephrine induced a conce...
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Published in | The Journal of pharmacology and experimental therapeutics Vol. 205; no. 1; pp. 175 - 182 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Pharmacology and Experimental Therapeutics
01.04.1978
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Subjects | |
Online Access | Get full text |
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Summary: | We studied the relationship between epinephrine-induced increases in automaticity and in the adenylate cyclase-adenosine 3',5'-monophosphate
(cAMP) system in canine cardiac Purkinje fibers. In intact Purkinje fiber bundles superfused with Tyrode's solution, epinephrine
induced a concentration-dependent increase in automaticity and in cAMP content. Both of these effects were reduced by propranolol.
Decreasing the temperature of the superfusate from 37 degrees to 25 degrees C blocked the epinephrine-induced increase in
automaticity, but not the increase in cAMP content. Addition of the metabolic blocking agent, iodoacetate, to the superfusate
did not block the effect on Purkinje fiber automaticity, but the cAMP content did not increase. In Purkinje fiber bundle whole
homogenates adenylate cyclase was stimulated more by isoproterenol than by epinephrine. Low concentrations of phenylephrine
decreased adenylate cyclase activity; higher concentrations induced an increase toward control values. Iodoacetate did not
significantly alter cyclase activity and did not affect its response to epinephrine. These students have shown that although
intact Purkinje fiber bundles respond to epinephrine with increases in automaticity and cAMP content, these two events can
be dissociated under appropriate conditions. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3565 1521-0103 |