Depressed transmembrane potentials during experimentally induced ventricular failure in cats.

Transmembrane potentials and isometric force were recorded in right ventricular muscles from cats with right ventricular failure 3-127 days after chronic partial pulmonary artery obstruction. For the majority of failed muscles (at 36°C, 30 stimuli/ min), resting potential, action potential overshoot, action potential maximum rate of rise, isometric active force at optimal length (Po), and dP/dt were decreased compared with the same parameters in normal muscles. Time to peak force and duration of contraction were unaltered. Action potential configuration was changed and action potential duration was lengthened in failed muscles. Epinephrine ( 1 ( H M ) markedly increased Po and resting potential in severely depolarized failed muscles. These data suggest that electrical depression might exacerbate the contractile deficit in experimental chronic right ventricular failure.