Effect of altered repolarization course induced by antiarrhythmic drugs and constant current pulses on duration of premature action potentials in canine cardiac Purkinje fibers.

Journal of Cardiovascular Pharmacology
Y NakayaB Surawicz

Abstract

The purpose of this study was to elucidate the mechanism of the upward shift of the electrical restitution curve, i.e., the lengthening of premature action potential duration (APDt) expressed as percentage of basic APD, induced by class I antiarrhythmic drugs in dog Purkinje fibers. In this study, six class I antiarrhythmic drugs lengthened APDt at a diastolic interval of 20 ms by 2.5-14.1%. The drugs also decreased the ratio of APD at 50% to APD at 90% of repolarization from 70.8 +/- 1.8% (n = 60) to 47.4-60.8%. The relation between the decrease in the ratio of APD50 to APD90 of the basic AP and lengthening of the normalized APDt was linear (r = 0.92; p less than 0.01). We attributed the lengthening of normalized APDt to the decreased ratio of APD50 to APD90, and applied repolarizing current pulses in short (less than or equal to 2 mm) fibers to simulate the drug-induced decrease in the ratio of APD50 to APD90. The altered repolarization course of basic AP by the current pulse during late plateau and early phase 3 caused APDt lengthening. The relation between the current-induced decrease in the ratio of APD50 to APD90 of the basic AP and the lengthening of normalized APDt was linear (r = 0.91; p less than 0.01). The slope of r...Continue Reading

Citations

Oct 12, 2005·Journal of Electrocardiology·Hiroyuki KimuraJyunichi Miyaki
May 13, 2015·International Journal of Cardiology·Pablo A ChialeMarcelo V Elizari
Dec 21, 2011·Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics·Alejandro GarzónFlavio H Fenton
Nov 14, 1998·The American Journal of Physiology·M L KollerR F Gilmour

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