Potentiation by naloxone of pressor reflexes.
1 The effect of intravenous naloxone, and opiate antagonist, was studied on the pressor responses elicited by stimulation of afferent nerves (vagus and laryngeal superior nerves) in anaesthetized dogs. 2 Although naloxone (0.1 mg/kg i.v.) alone failed to modify basic blood pressure, the pressor responses induced by stimulation of either the vagus or laryngeal nerve were potentiated by naloxone. 3 Morphine (0.2 mg/kg i.v.) suppressed these two cardiovascular responses. These depressor effects of morphine were reversed by subsequent injection of naloxone (0.1 mg/kg i.v.). 4 The results suggest the involvement of endogenous opiate peptides in pressor reflexes elicited by stimulation of the afferent nerves.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology*; D009475:Neurons, Afferent / Q000502:physiology; D012018:Reflex / Q000187:drug effects*
D009270:Naloxone; D009020:Morphine