title: Effects of an antihypertensive agent, nipradilol, on isolated coronary artery of the dog.
abstract: Effects of nipradilol on proximal, middle and distal portions of left coronary arteries of the dog were investigated in vitro. Nipradilol (10(-7)-10(-3) M) produced a concentration-dependent relaxation in helical strips of isolated coronary artery under potassium contracture. The relaxation in the middle portions was most pronounced, it was 10% of the equimolar concentrations of nitroglycerin and significantly greater than that of propranolol. In the proximal portions of the coronary arteries, nipradilol (3 X 10(-8)-3 X 10(-7) M) showed a tendency to augment the contractile responses to norepinephrine; in the middle portions it reversed the relaxant responses to norepinephrine into contractile effects in a concentration-dependent manner. In distal portions, nipradilol significantly decreased the relaxant responses of the strips to norepinephrine. The findings demonstrate direct vasodilating and beta-adrenoceptor blocking actions of nipradilol in isolated coronary arteries of the dog.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D005996:Nitroglycerin / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology
chemical_list: D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D011412:Propanolamines; D011433:Propranolol; C036089:nipradilol; D005996:Nitroglycerin; D011188:Potassium; D009638:Norepinephrine