Involvement of central alpha-adrenoceptors in the hypotensive and bradycardic effects of (--)-delta 9-trans-tetrahydrocannabinol.
I.v. administration of (--)-delta9-trans-tetrahydrocannabinol (delta 9-THC) to chloralose-anesthetized cats produced a decrease in blood pressure and heart rate. Studies conducted to investigate the mechanism of these changes revealed that the hypotensive and bradycardic effects of delta 9-THC (0.1 mg/kg, i.v.) could be significantly antagonized following intraventricular (i.v.t.) perfusion with alpha-adrenergic receptor blocking agent phentolamine, while a larger dose of delta 9-THC (0.25 mg/kg, i.v.) still produced significant hypotension and bradycardia. I.v.t. perfusion of phentolamine (100 mug/min for 30 min) caused a fall in blood pressure and heart rate which were reversible and produced blockade of central alpha-adrenergic receptors. These results provide evidence for the involvement of central alpha-adrenergic receptors in the hypotensive and bradycardic actions of delta 9-THC and indicate that other receptor mechanisms may also be involved in mediating these responses observed following administration of delta 9-THC.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002415:Cats; D003864:Depression, Chemical; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D013759:Dronabinol; D010646:Phentolamine