PMID: 10549Oct 15, 1976

Influence of low extracellular pH upon the Ca inward current and isometric contractile force in mammalian ventricular myocardium

Pflügers Archiv : European journal of physiology
M KohlhardtH R Figulla

Abstract

In isolated papillary muscles of cats the changes in Ca inward current and isometric contractile force following a decrease of extracellular pH from 7.4 to 5.5 were studied. The Ca current was analyzed (a) by measuring the upstroke velocity of Ca-mediated action potentials and (b) in voltage clamp experiments using the double sucrose gap technique. 1. At a pH of 5.5 the upstroke velocity of the Ca-mediated action potential decreased to 65% of the control, while overshoot and action potential duration remained almost unchanged. Furthermore, the relative refractory period was prolonged and in some cases, a "Wenckebach-like" phenomenon occurred. In voltage clamp experiments, the slow inward current was found to be diminished to 50-60% of the initial control value and over a broad voltage range the current voltage relationship curve was shifted to weaker currents. Acidosis did not influence the steady state inactivation but altered the kinetics of inactivation of the slow inward current and induced an increase of tauinactivation and taurecovery. This indicates that acidosis exerts a complex effect on the slow membrane channel. 2. The normal response of the Ca current towards variations of the extracellular Ca concentration (0.5-4 m...Continue Reading

References

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Citations

Oct 1, 1982·Pflügers Archiv : European journal of physiology·G Isenberg, U Klöckner
Sep 1, 1982·Pflügers Archiv : European journal of physiology·Y Kurachi
Jan 1, 1988·Cardiovascular Drugs and Therapy·W A Coetzee
Jan 1, 1988·Cardiovascular Drugs and Therapy·W MarkiewiczJ Wikman-Coffelt
Feb 1, 1981·Journal of Molecular and Cellular Cardiology·A YataniM Goto
Sep 1, 1995·Journal of Molecular and Cellular Cardiology·G J Rozanski, R C Witt
Jul 20, 2002·Life Sciences·Kaoru HattoriI Muramatsu
Jan 1, 1983·Progress in Cardiovascular Diseases·E C Keung, R S Aronson
Jan 1, 1985·Journal of Molecular and Cellular Cardiology·B VanheelI Leusen
Jul 2, 2008·Brazilian Journal of Medical and Biological Research = Revista Brasileira De Pesquisas Médicas E Biológicas·A C CelottoP R B Evora
Feb 1, 1987·Circulation Research·D G Allen, C H Orchard
Oct 1, 1988·Circulation Research·R J SolaroD G Allen
May 1, 1978·Circulation Research·E Carmeliet
Mar 20, 1998·Circulation Research·M C Camilión de HurtadoH E Cingolani
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Jul 1, 1987·The American Journal of Physiology·D Kim, T W Smith
Sep 1, 1989·The Journal of Pharmacy and Pharmacology·M Shahid, I W Rodger

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