RT Journal Article
SR Electronic
T1 The effects of verapamil and lidocaine on the automatic depolarizations in guinea-pig ventricular myocardium.
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 294
OP 303
VO 207
IS 2
A1 S Imanishi
A1 R G McAllister, Jr
A1 B Surawicz
YR 1978
UL http://jpet.aspetjournals.org/content/207/2/294.abstract
AB Rhythmic automatic depolarizations (RAD) were produced in guinea-pig papillary muscles depolarized to membrane potentials at which depolarizations depend on membrane currents passing through the slow channel. Verapamil depressed the RAD and decreased their overshoot. These verapamil effects were dependent on its concentration either in the bath (in vitro) or in plasma and myocardium (in vivo). Increase in [Ca++] counteracted the effects of verapamil on RAD. Lidocaine concentrations ranging from 4 to 16 mg/l had no effect on overshoot and only a slight effect on the rate of RAD. We conclude that RAD are more sensitive to nonlethal and presumably therapeutic concentrations of verapamil than to high, presumably toxic, concentrations of lidocaine.