title: Continuous intravenous infusion of LY171555, a potent selective D2 receptor agonist, lowers blood pressure in the conscious rat.
abstract: Cardiovascular responses to sustained infusion of quinpirole (LY171555), a dopamine (DA) D2 receptor agonist, and bolus injection of quinpirole following sustained infusion were examined in conscious, unrestrained Sprague-Dawley rats to investigate the contributions of central and peripheral D2 receptors to the regulation of cardiovascular function. Continuous intravenous administration of quinpirole induced a transient pressor response followed by normalization of mean arterial pressure (MAP) and, at higher doses, a decrease in MAP below control levels. Intravenous bolus injections of quinpirole administered 30 min after termination of the infusion produced dose-dependent depressor responses which were blocked by pretreatment with domperidone, a peripheral D2 antagonist. The data suggest that continuous intravenous administration of quinpirole produces a transient centrally mediated pressor effect which is followed by a more sustained, peripherally mediated depressor response.
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects*; D002395:Catecholamines / Q000097:blood; D004294:Domperidone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; 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*; D017448:Receptors, Dopamine D2
chemical_list: D002395:Catecholamines; D004873:Ergolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D001127:Arginine Vasopressin; D019257:Quinpirole; D004294:Domperidone