Cardiovascular effects of dopamine after central administration into conscious cats.
Dopamine (30 and 45 mug) administered intracerebroventricular (i.c.v.) to a group of 10 conscious normotensive cats caused dose-related increases in blood pressure and heart rate. In 4 of these animals the initial cardiovascular stimulant effects of i.c.v. dopamine were followed by hypotension and bradycardia. 2 alpha-Methyldopamine (30 and 45 mug i.c.v.) produced qualitatively similar responses to dopamine except that the cardiovascular stimulant effects were smaller and the secondary depressant effects somewhat more prolonged. 3 Both stimulant and depressant effects of i.c.v. dopamine and alpha-methyldopamine were greatly inhibited by autonomic ganglion blockade or by adrenergic neurone blockade. 4 The cardiovascular stimulant effects of both i.c.v. dopamine and i.c.v. alpha-methyldopamine were selectively inhibited by beta-adrenoceptor blocking agents whilst the cardiovascular depressant effects of these substances were abolished by the alpha-adrenoceptor blocker phentolamine or by the dopamine-beta-hydroxylase inhibitor disulfiram. 5 Haloperidol by either i.c.v. or the intravenous route abolished both cardiovascular stimulant and depressant effects of i.c.v. dopamine, whilst pimozide by either route inhibited only the cardiovascular stimulant effects. 6 In 2 cats, injection of dopamine into the cisterna magna produced predominantly depressant effects on the cardiovascular system except with a higher dose which induced biphasic responses.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D002946:Cisterna Magna; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors; D005260:Female; D005730:Ganglionic Blockers / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007267:Injections; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008750:Methyldopa / Q000494:pharmacology; D011954:Receptors, Dopamine / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D005730:Ganglionic Blockers; D011954:Receptors, Dopamine; D008750:Methyldopa; D004299:Dopamine beta-Hydroxylase; D007545:Isoproterenol; D004298:Dopamine