Section 29
Chapter 28,939

Potassium currents in cardiac cells

Carmeliet, E.; Biermans, G.; Callewaert, G.; Vereecke, J.

Experientia 43(11-12): 1175-1184


ISSN/ISBN: 0014-4754
PMID: 2446912
DOI: 10.1007/bf01945519
Accession: 028938539

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The kinetic properties of the inwardly rectifying K current and the transient outward current in cardiac cells were investigated. In sheep Purkinje fibers superfused with Na-free K-free solution, time-dependent changes in the conductance of the inward rectifier are described. In patch clamp experiments the inward rectifier inactivates during hyperpolarization, as can be seen by a decrease in the open state probability. Using whole cell clamp on ventricular myocytes it is demonstrated that the inactivation during hyperpolarization is due to blocking of the channel by external Na, Mg and Ca. The channels responsible for the transient outward current in cow, sheep and rabbit Purkinje fibers are identified using single channel recording. It is demonstrated that in all three preparations the channels are K-selective. The channel in cow Purkinje cells has a large conductance and is regulated by voltage and internal Ca concentration. The channels identified in the sheep and rabbit cells have a much smaller conductance.

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