title: Subsensitivity of the presynaptic dopamine receptors in cat heart after the termination of chronic haloperidol treatment.
abstract: The effects of chronic haloperidol treatment on presynaptic dopamine receptor sensitivity were studied on cat cardioaccelerator nerve terminals. Apomorphine and N, N-dimethyldopamine, two dopamine receptor agonists, caused inhibition of heart rate increase produced by postganglionic cardioaccelerator nerve stimulation. After termination of chronic haloperidol treatment, inhibition induced by apomorphine and N, N-dimethyldopamine was attenuated. The hypotensive and bradycardic effects of apomorphine did not change. Chronic haloperidol treatment did not alter the positive chronotropic responses of tyramine, isoproterenol or norepinephrine. These results suggest that presynaptic dopamine receptors on cat cardioaccelerator nerve terminals become subsensitive following withdrawal of chronic haloperidol treatment.
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D005260:Female; D006220:Haloperidol / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011954:Receptors, Dopamine / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology; D014439:Tyramine / Q000494:pharmacology
chemical_list: D011954:Receptors, Dopamine; D006220:Haloperidol; D007545:Isoproterenol; D001058:Apomorphine; D009638:Norepinephrine; D014439:Tyramine