Postrest shortening of the action potential duration in rabbits: in vitro and in vivo correlation.

摘要: Previous evidence has shown that the action potential duration of rabbit ventricular muscle cells shortens after a rest period (postrest shortening). However, there not been much research on postrest shortening in intact heart. We recorded transmembrane potentials (TAPs) isolated papillary from ventricle with glass microelectrodes and monophasic (MAPs) left endocardium contact electrodes. In vitro experiments, repetitive regular stimuli (S1) at cycle length 1 sec were followed by single extrastimulus (S2) coupling intervals (S1S2) ranging between 0.5 8 sec. The increase S1S2 interval resulted progressive TAP elicited S2, which was abolished simultaneous application mmol/L 4-aminopyridine 2 micromol/L ryanodine. vivo right pacing 0.35 0.25 3 also MAP S2. This is first report to demonstrate heart, probably occurs because mechanism analogous observed muscle.