Control of the frog heart relaxation by Na-Ca exchange

Details

Serval ID
serval:BIB_1B2AF2A6261A
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Control of the frog heart relaxation by Na-Ca exchange
Journal
European Journal of Cardiology
Author(s)
Vassort  G. M., Roulet  M. J., Mongo  K. G., Ventura-Clapier  R. F.
ISSN
0301-4711 (Print)
Publication state
Published
Issued date
06/1978
Volume
7 Suppl
Pages
17-25
Notes
Journal Article --- Old month value: Jun
Abstract
Frog heart relaxation was analysed under voltage clamp conditions as the tension decay observed after membrane potential had been stepped back to its resting value. It appeared mostly exponential with a time constant of about 190 msec. Relaxation rate decreased with the external Na concentration. It fell to 1/10 in a Na-free solution. Relaxation rate decreased also following an increase in the intracellular Na content by application of veratrine. When switching from a high to a low Na-containing solution the relaxation rate reached rapidly a value transiently higher than the steady-state's (and vice versa). In Na-free solution, adrenaline accelerated tension decay, an effect not noticeable on frog heart in Ringer solution. In frog myocardium, part of the intracellular Ca concentration decrease which occurs during each cardiac cycle directly results from a calcium extrusion carried out by the Na-Ca exchange. Such a Ca decrease, besides internal Ca storage, should play a primary role in the relaxation of contractile tissues whose cells have a large surface/volume ratio.
Keywords
Animals Anura Calcium/*physiology Epinephrine/pharmacology Heart/drug effects/*physiology Ion Exchange Membrane Potentials *Myocardial Contraction/drug effects Sodium/pharmacology/*physiology Veratrine/pharmacology
Pubmed
Web of science
Create date
24/01/2008 20:33
Last modification date
20/08/2019 12:51
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