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.
Department of Physiology and Pharmacology, School of Medicine, Murcia, Spain.
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S
Alarcón
J
J
Hernández
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ML
Laorden
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