Cardiovascular effects of etorphine in rats.
1. Cardiovascular effects of intravenously administered etorphine were investigated in mechanically ventilated normotensive rats under pentobarbitone anaesthesia. 2. Etorphine (0.1-2 micrograms kg-1) induced a dose-related bradycardia and hypotension which was prevented by pretreatment with naloxone (0.1 mg kg-1). 3. After bilateral vagotomy etorphine (1 microgram kg-1) produced a pressor effect which was prevented by prazosin (0.5 mg kg-1), but unaltered by adrenalectomy. 4. The bradycardia due to etorphine was abolished by bilateral vagotomy, but only partially reduced by atropine (1 mg kg-1) and still evident after propranolol (1.5 mg kg-1). 5. Etorphine was without effect on blood pressure in the pithed rat, although there was a small bradycardia which was not seen after naloxone. 6. The data presented indicate that etorphine produces an opioid receptor-mediated stimulation of both vagal (partially cholinergic) and sympathetic outflow and a direct cardiodepressant effect.
Roquebert
J
J
UER de Pharmacie, Université de Bordeaux, France.
Delgoulet
C
C
D000315:Adrenalectomy; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D005048:Etorphine / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D009019:Morphinans / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014628:Vagotomy
D009019:Morphinans; D009270:Naloxone; D005048:Etorphine; D001285:Atropine; D011433:Propranolol; D011224:Prazosin