Central cardiovascular effects of morphinomimetic peptides in dogs.
Morphinomimetic peptides were injected into the cisterna magna of chloralosed dogs. Methionine enkepalin (500 microgram/kg i.c.) was found ineffective but beta-endorphin (50 microgram/kg i.c.) induced an initial and transient increase in blood pressure and heart rate followed by a delayed hypotension and bradycardia. The synthetic pentapeptides, [d-ala2]met-enkephalin (500 microgram/kg i.c.), [d-ala2]met-enkephalinamide 500 microgram/kg i.c.) also induced a marked hypotensive, bradycardic and sympatho-inhibitory effect. High doses of naloxone (100 microgram/kg i.v.) were required to antagonize these effects transiently.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002946:Cisterna Magna; D004285:Dogs; D004723:Endorphins / Q000008:administration & dosage / Q000494:pharmacology*; D004745:Enkephalins / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007267:Injections; D008297:Male
D004723:Endorphins; D004745:Enkephalins