Electrophysiological effects of opioid receptor selective agonists on guinea-pig papillary muscle.
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 ventricular 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 potential characteristics. However, U.-50,488H (10(-5),5.10(-5) M) caused a concentration-dependent reduction in the maximum rate of depolarization of phase 0 (Vmax) and in the action potential duration measured at 50% repolarization, APD50 and 90% repolarization, APD90. 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.
Alarcón
S
S
Department of Physiology and Pharmacology, University School of Medicine, Murcia, Spain.
Hernández
J
J
Laorden
M L
ML
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000200:Action Potentials / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D004745:Enkephalins / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology; D017465:Receptors, Opioid, delta / Q000819:agonists*; D017473:Receptors, Opioid, kappa / Q000819:agonists*; D017450:Receptors, Opioid, mu / Q000819:agonists*
D004745:Enkephalins; D011759:Pyrrolidines; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D020881:Enkephalin, D-Penicillamine (2,5)-