Identification of dopamine receptor subtypes in the hypotensive action of SK&F 85174 in anesthetized rats.
1 We have performed experiments to determine the effect of SK&F 85174 on blood pressure in anaesthetized rats and identify dopamine receptor subtype(s) involved in its action. 2 SK&F 85174 decreased blood pressure in a dose-related manner. There were no significant changes in heart rate. The hypotensive action was short-lasting and was significantly antagonized by the selective DA1-receptor antagonist. SCH 23390 (100 micrograms/kg). This dose of SCH 23390 did not alter the hypotension produced by the DA2-receptor agonist, quinpirole. 3 The DA2-receptor antagonist, domperidone (25 micrograms/kg), did not significantly alter the hypotension produced by lower doses of SK&F 85174, but antagonized the hypotensive action of the highest dose of SK&F 85174 by about 35%. This dose of domperidone antagonized the hypotension produced by quinpirole by 85% without affecting the hypotensive action of the DA1-receptor agonist, fenoldopam. 4 These results show that at lower doses of SK&F 85174, the hypotension is due primarily to DA1-receptor activation, whereas DA2-receptor activation may also contribute to the blood pressure decrease produced by higher doses of SK&F 85174.
D000758:Anesthesia; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D004294:Domperidone / Q000494:pharmacology; D004873:Ergolines / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*
D014150:Antipsychotic Agents; D001552:Benzazepines; D004873:Ergolines; D011954:Receptors, Dopamine; D019257:Quinpirole; D004294:Domperidone; C045977:SK&F 85174