The study demonstrates that Na+-Ca2+ exchange in cardiac sarcolemmal vesicles is an electrogenic process, which may play a key role in controlling myocardial tension development.
May modulate myocardial tension via electrogenic exchange; leaves open in vivo role and clinical relevance.
The effect of membrane potential on the Na+-Ca2+ exchange activity of isolated sarcolemmal vesicles from dog ventricles is examined. Na+-Ca2+ exchange is monitored as Nai+-dependent Ca2+ uptake as described by Reeves and Sutko ((1979) Proc. Natl. Acad. Sci. U. S. A. 76,590-594). Membrane potential is controlled by varying internal and external K+ in the presence of valinomycin. Inside-positive potentials stimulate Nai+-dependent Ca2+ influx. This stimulation is independent of Ca2+ concentration. The results indicate that Na+-Ca2+ exchange by itself can generate a substantial potential (approximately -60mV) in the sarcolemmal vesicles. The data are consistent with an electrogenic Na+-Ca2+ exchange mechanism in which three or more Na+ are exchanged for one Ca2+. This electrogenic exchange may have important implications in the control of myocardial tension development.
No takes yet. Share an insight, caveat, or question.
Philipson et al. (1980) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: