Effects of a K ionophore, lonomycin A, on the action potential in canine cardiac Purkinje fibers

Japanese Journal of Pharmacology
K Tsuchida, H Aihara

Abstract

Effects of a K ionophore, lonomycin A (K+:Na+ = 6:1), on the action potential and contractile force in canine cardiac Purkinje fibers were examined. Lonomycin A increased the developed and resting tensions. The agent shortened the action potential, decreased the plateau height and suppressed the automaticity. In addition, lonomycin A also shortened the duration of the slow action potential response, and it shortened the action potential duration to about the same extent in the presence and absence of tetrodotoxin. In quiescent Purkinje fibers, lonomycin A decreased K content in both 1.8 mM Ca Tyrode's solution (contracture observed) and 0.18 mM Ca Tyrode's solution (contracture not observed). These results suggest that lonomycin A-induced changes in the action potential configuration of Purkinje fibers is mainly due to the increase in K conductance, and the increase is induced irrespective of the degree of the increased [Ca2+]i.

References

Apr 1, 1975·The American Journal of Physiology·K Shigenobu, N Sperelakis
May 1, 1985·Japanese Journal of Pharmacology·K TsuchidaS Chiba
Nov 1, 1967·Proceedings of the National Academy of Sciences of the United States of America·B C PressmanJ H Johnson
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Mar 1, 1973·The Journal of Physiology·T F McDonald, D P MacLeod

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Citations

Nov 22, 2013·ISRN Pharmacology·Katsuharu TsuchidaYukiko Naito

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