Publication Date:
1988-08-12
Description:
Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bridge, J H -- Spitzer, K W -- Ershler, P R -- HL31140/HL/NHLBI NIH HHS/ -- HL34288/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1988 Aug 12;241(4867):823-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, UT.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3406740" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Caffeine/pharmacology
;
Electric Stimulation
;
Guinea Pigs
;
Heart/*physiology
;
In Vitro Techniques
;
Membrane Potentials/drug effects
;
*Myocardial Contraction/drug effects
;
Perfusion
;
Sarcolemma/drug effects/physiology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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