title: The lack of the effect of DA-1 and DA-2 dopamine agonists on the isolated guinea-pig atria.
abstract: 1 The effects of dopamine and both DA-1 and DA-2 dopamine receptor agonists have been studied on the contractile force of electrically driven guinea-pig left atria and frequency of spontaneously beating right atria. 2 Pretreatment of animals with reserpine caused a parallel rightward shift of the concentration-response curve to dopamine of either preparation. 3 Propranolol, but not domperidone, shifted to the right the dose-response curve for the positive inotropic and chronotropic effects of dopamine. 4 Neither apomorphine, fenoldopam, bromocriptine nor piribedil had effects on the frequency and contractile force of the isolated guinea-pig atria. 5 These results suggest that DA-1 and DA-2 dopamine receptors are neither directly nor indirectly (prejunctional effect) involved in the inotropic and chronotropic effects of dopamine in isolated guinea-pig atria.
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D001971:Bromocriptine / Q000494:pharmacology; D004294:Domperidone / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D018818:Fenoldopam; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D010891:Piribedil / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology*; D011954:Receptors, Dopamine / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D001552:Benzazepines; D011954:Receptors, Dopamine; D014665:Vasodilator Agents; D001971:Bromocriptine; D004294:Domperidone; D011433:Propranolol; D010891:Piribedil; D018818:Fenoldopam; D001058:Apomorphine