Effects of morphine: an electrophysiological study on guinea-pig papillary muscle.
Intracellular microelectrodes were used to study the electrophysiological effects of morphine on guinea-pig papillary muscle. Morphine (5 x 10(-4) M) caused a significant decrease in the maximum rate of depolarization. At high concentrations (5 x 10(-3) M) morphine induced a decrease in the action potential amplitude and a prolongation of the action potential duration. The administration of naloxone (10(-7) M) partially antagonized the cardiac electrophysiological effects of morphine. These results suggest that the electrophysiological effects of morphine may be due to an interaction with opioid receptors.
Alarcón
S
S
Department of Physiology and Pharmacology, School of Medicine, Murcia, Spain.
Hernández
J
J
Laorden
M L
ML
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004594:Electrophysiology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D010210:Papillary Muscles / Q000187:drug effects
D009270:Naloxone; D009020:Morphine