AJP - Heart and Circulatory Physiology, Vol 246, Issue 4 630-H634, Copyright © 1984 by American Physiological Society
Injection of protein kinase inhibitor into cultured heart cells blocks calcium slow channels
G. Bkaily and N. Sperelakis
An inhibitor of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent
protein kinase was injected into cultured heart cells (reaggregates) by the
phosphatidylcholine liposome method. The inhibitor blocked both the
isoproterenol-induced slow action potentials and the spontaneously
occurring slow action potentials of these cells. The inhibitory effect of
protein kinase inhibitor was prevented by denaturation or reversed by the
injection of the catalytic subunit of cAMP-dependent protein kinase. These
findings support the phosphorylation hypothesis for the myocardial slow
channels, namely that the slow channel protein must be phosphorylated for
the channel to be available for voltage activation.
