Myocardial action potential configuration

Measurement of the Concentration of Test Article in in vitro Systems 

Franz MR (1991) Method and theory of monophasic action potential recording. Progress in Cardiovascular Diseases 6 347-368 

Herron W, Towers C, Templeton A (2004) Experiences in method development for the analysis of in vitor study solutions for content. J Pharmacol Toxicol Methods 49 211-216 

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It is established that Ca + and K+ are involved in maintenance and termination of the plateau phase of the cardiac action potential. Furthermore, intracellular calcium concentration controls membrane K+ permeability via the various conductance components for K+ (gK], gK2, glx) (69) It is also established that action potential duration and myocardial tension development are integrally related (13). In view of previous observations and explanations for the excitation-contraction coupling process and the effects of calcium inhibitory compounds upon the cardiac action potential of ventricular muscle and Purkinje fibers, one possible explanation for the effects observed in ventricular muscle preparations is that low concentrations of calcium inhibitory compounds reduce the amount of intracellular free calcium in the vicinity of the K+ channel, thereby changing the channel s configuration resulting in a reduction in gK+ and delayed repolarization of the ventricular muscle action potential. 

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