AJP - Heart and Circulatory Physiology, Vol 250, Issue 5 731-H735, Copyright © 1986 by American Physiological Society
Electrophysiological properties of cultured adult rat ventricular cardiac muscle cells
C. F. Meier Jr, G. M. Briggs and W. C. Claycomb
Action and resting potential characteristics of isolated adult rat
myocardial cells maintained in culture for 10-28 days are described.
Resting potentials averaged -76.3 +/- 2 mV in 5 mM extracellular [K+]
([K+]o). Resting potentials changed by 54.3 mV/decade change in [K+]o for
concentrations greater than 5 mM. The average maximum rate of rise of
action potential (Vmax) was 117.7 +/- 10 V/s with overshoots of 34.6 +/-
2.5 mV. Action potential durations (APD) to 0 and -40 mV and full
repolarization were 21.8 +/- 3.9, 36.3 +/- 6.0, and 206 +/- 16.9 ms
respectively. Action potential configurations were qualitatively similar to
those previously reported by others for rat myocardial tissue or freshly
dissociated cells. Tetrodotoxin (4 micrograms/ml) decreased Vmax to less
than 24 V/s and decreased overshoot and APD. Isoproterenol (10(-8) M)
decreased APD with slight elevation of the overshoot. Verapamil (10(-5) to
10(-4) M) depressed overshoot and plateau while slowing the final phase of
repolarization. Verapamil (10(-4) M) depressed upstroke velocity and
blocked excitability. While APDs recorded from these cultured cells are
apparently longer than those reported by others for rat myocardial APDs,
the values of all other electrophysiological parameters recorded are within
the limits previously reported for normal rat myocardial tissue. These data
indicate that adult rat myocardial cells maintained in tissue culture for
10-28 days possess electrophysiological properties and responses to
pharmacological agents similar to adult rat myocardial tissue or undamaged
freshly isolated cells.
