S. Alarcon et al., ELECTROPHYSIOLOGICAL EFFECTS OF OPIOID RECEPTOR-SELECTIVE AGONISTS ONGUINEA-PIG PAPILLARY-MUSCLE, Regulatory peptides, 55(2), 1995, pp. 149-154
The cardiac electrophysiological effects of DAMGO, DPDPE and U-50,488H
which are selective opioid agonists for mu, delta and kappa receptors
, respectively, were studied in the isolated guinea-pig right ventricu
lar papillary muscles. Neither DAMGO (5.10(-6)-5.10(-5)M) nor DPDPE (5
.10(-6)-5.10(-5)M) produced any significant effect on the action poten
tial characteristics. However, U-50,488H (10(-5), 5.10(-5) M) caused a
concentration-dependent reduction in the maximum rate of depolarizati
on of phase 0 (V-max) and in the action potential duration measured at
50% repolarization, APD(50) and 90% repolarization, APD(90). At 5.10(
-5) M it also produced a decrease of action potential amplitude (APA).
These results suggest that the reported electrophysiological effects
of U-50,488H on the cardiac muscle action potential, may be, at least
in part, explained by a direct cardiac action.