title: Hypotensive and vascular effects of labetalol in the normotensive rat and dog.
abstract: A new antihypertensive agent, labetalol, has potent hypotensive effects in the anesthetized rat and dog when given intravenously and also in the unanesthetized beagle when given orally. Labetalol slightly increased renal blood flow of the anesthetized dog while decreasing blood pressure. Labetalol slightly increased blood flow of canine femoral artery under constant pressure perfusion. However as compared with hydralazine, labetalol seems to have no marked vasodilatatory effect which accounts for its hypotensive effect. Pharmacologically, labetalol possessed both alpha- and beta-blocking activities, though weaker than phentolamine and propranolol respectively. Another specific action of labetalol was that it has stronger beta-blocking action on beta1 receptor (heart rate response) than on beta2 receptor (blood pressure response). Like several other beta-blockers, labetalol seems to block neuronal uptake of noradrenaline.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D005263:Femoral Artery / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D007668:Kidney / Q000098:blood supply; D007741:Labetalol / Q000494:pharmacology*; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D012039:Regional Blood Flow / Q000187:drug effects; D014666:Vasomotor System / Q000187:drug effects*
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D004983:Ethanolamines; D011433:Propranolol; D007545:Isoproterenol; D007741:Labetalol; D010646:Phentolamine