Na+-Ca2+ exchange contributes to increase of cytosolic Ca2+ concentration during depolarization in heart muscle
- 1 April 1986
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Cell Physiology
- Vol. 250 (4), C651-C656
- https://doi.org/10.1152/ajpcell.1986.250.4.c651
Abstract
The possible role of Na+-Ca2+ exchange in contributing to depolarization-induced increase in cytosolic Ca2+ concentration ([Ca2+]i) of isolated rat ventricular myocytes was investigated. Measured with the Ca2+-sensitive indicator quin 2, [Ca2+]i increased from 177 +/- 12 (mean +/- SE, n = 11) to 468 +/- 41 nM when cells were depolarized with solutions containing 50 mM KCl [high extracellular K+ concentration ([K+]o)]. Approximately 73% of this high-[K+]o-induced increase in [Ca2+]i was abolished by the Ca2+ channel blocker verapamil (5 microM). For cells pretreated with 10 mM caffeine to deplete the Ca2+ stored in sarcoplasmic reticulum, 50 mM KCl still produced an increase in [Ca2+]i, even in the presence of 5 microM verapamil. However, if extracellular Na+ was replaced by Li+ or tris(hydroxymethyl)aminomethane, this increase was completely abolished. The results suggest that, in addition to voltage-sensitive Ca2+ channels, voltage-sensitive Na+-Ca2+ exchange can also contribute to the increase in [Ca2+]i on depolarization. Therefore both Ca2+ transport systems may play important roles in regulating cardiac excitation and contraction.This publication has 40 references indexed in Scilit:
- Intracellular Ca indicator Quin-2 inhibits Ca2+ inflow via Nai/Cao exchange in squid axonNature, 1985
- Do caffeine and metabolic inhibitors increase free calcium in the heart? Interpretation of conflicting intracellular calcium measurementsJournal of Molecular and Cellular Cardiology, 1985
- Excitation-contraction coupling in cardiac Purkinje fibers. Effects of caffeine on the intracellular [Ca2+] transient, membrane currents, and contraction.The Journal of general physiology, 1984
- Transmembrane Na+ and Ca2+ electrochemical gradients in cardiac muscle and their relationship to force development.The Journal of general physiology, 1982
- The "late" Ca channel in squid axons.The Journal of general physiology, 1981
- Calcium ChannelAnnual Review of Neuroscience, 1981
- Sodium-calcium exchange in regulation of cardiac contractility. Evidence for an electrogenic, voltage-dependent mechanism.The Journal of general physiology, 1979
- Calcium influx in internally dialyzed squid giant axons.The Journal of general physiology, 1978
- Slow inward current and contraction of sheep cardiac Purkinje fibers.The Journal of general physiology, 1975
- High Potassium and Low Sodium Contractures in Sheep Cardiac MuscleThe Journal of general physiology, 1971