Cardiovascular effects of prazosin in normotensive and genetically hypertensive rats.
1. The cardiovascular effects of prazosin, a new antihypertensive drug, were studied in normotensive and genetically hypertensive rats. 2. Prazosin, infused intra-arterially, lowered vascular resistance in the blood-perfused rat hind limb. This effect was dependent on the presence of intact sympathetic innervation to the limb; no direct vasodilatation was demonstrated. In this preparation prazosin infusion reduced vasoconstrictor responses to noradrenaline. 3. In the saline-perfused rat mesenteric artery preparation prazosin reduced responses to noradrenaline and sympathetic nerve stimulation but not those to serotonin and vasopressin. Prazosin was more potent than phentolamine, on a molar basis, in reducing the vasoconstrictor effects of noradrenaline. 4. A comparison of the effects of prazosin injected intravenously and into a lateral cerebral ventricle failed to show any central action of the drug on blood pressure. Experiments using the donor blood-perfused, vascularly isolated rat hind limb preparation confirmed that the sympatholytic effect of prazosin occurred within the limb itself.
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects*; D006614:Hindlimb / Q000098:blood supply; D006973:Hypertension / Q000503:physiopathology*; D008638:Mesenteric Arteries / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D010879:Piperazines / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology*; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects
D000959:Antihypertensive Agents; D010879:Piperazines; D011799:Quinazolines; D009638:Norepinephrine