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Type: Artigo de periódico
Title: Contribution Of Ca(2+) Transporters To Relaxation In Intact Ventricular Myocytes From Developing Rats.
Author: Bassani, Rosana A
Bassani, José W M
Abstract: The relative contributions of Ca(2+) transporters to intracellular Ca(2+) concentration ([Ca(2+)](i)) decline associated with twitch relaxation were analyzed in intact ventricular myocytes from developing and adult rats. This was accomplished by estimation of individual integrated Ca(2+) fluxes with the use of kinetic parameters calculated from [Ca(2+)](i) measurements during twitches and caffeine-evoked contractures, and from myocardial passive Ca(2+) buffering data. Our main findings were the following: 1) twitch relaxation and [Ca(2+)](i) decline were significantly slower during the first postnatal week than in adults, 2) inhibition of sarcoplasmic reticulum (SR) Ca(2+) accumulation resulted in faster [Ca(2+)](i) decline in young cells than in adult cells, 3) the contributions of the SR Ca(2+) uptake and Na(+)/Ca(2+) exchange (NCX) to twitch relaxation increased from ~75 to 92%, and decreased from 24 to 5%, respectively, from birth to adulthood, and 4) Ca(2+) transport by the sarcolemmal Ca(2+)-ATPase was apparently increased in neonates. Our data indicate that despite a marked increase in NCX contribution to cell relaxation in immature rats, the SR Ca(2+)-ATPase appears to be the predominant transporter responsible for relaxation-associated [Ca(2+)](i) decline from birth to adulthood.
Subject: Aging
Calcium-binding Proteins
Calcium-transporting Atpases
Carbonyl Cyanide P-trifluoromethoxyphenylhydrazone
Heart Ventricles
Myocardial Contraction
Rats, Wistar
Sarcoplasmic Reticulum
Ventricular Function
Citation: American Journal Of Physiology. Heart And Circulatory Physiology. v. 282, n. 6, p. H2406-13, 2002-Jun.
Rights: fechado
Identifier DOI: 10.1152/ajpheart.00320.2001
Date Issue: 2002
Appears in Collections:Unicamp - Artigos e Outros Documentos

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