Effect of bulbocapnine as a peripheral dopamine receptor antagonists in the anesthetized cat.
We have found bulbocapnine to be an effective, apparently competitive inhibitor of dopamine depressor responses in the anesthetized, phenoxybenzamine-treated cat. The duration of action of the compound as a dopaminergic antagonist exceeded 3 hrs after an intravenous dose of 8 mg/kg. In the same preparation, however bulbocapnine did not at all inhibit the depressor responses to acetylcholine, histamine and isoproterenol, indicating a selectivity of action. Although administration of a high dose of propranolol (2 mg/kg, i.v.) did not alter the response of the alpha-receptor blocked cat to dopamine, the subsequent infusion of bulbocapnine remained effective. These results suggest that dopamine is acting as a blood pressure depressor agent via a unique receptor mechanism.
D000758:Anesthesia; D000818:Animals; D001060:Aporphines / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011955:Receptors, Drug / Q000187:drug effects*; D013997:Time Factors; D014665:Vasodilator Agents / Q000494:pharmacology
D001060:Aporphines; D011955:Receptors, Drug; D014665:Vasodilator Agents; D010643:Phenoxybenzamine; D011433:Propranolol; D007545:Isoproterenol; D004298:Dopamine