title: A pharmacological investigation on a possible calcium antagonistic action of propranolol.
abstract: The present study was designed to investigate the mechanisms of smooth muscle relaxant effects of propranolol. The relaxant effects of the drug on potassium (K+)-contracture or lanthanum (La3+)-contracture were studied using smooth muscle preparations of dog coronary artery and colon in comparison with those of nitroglycerin, nifedipine and papaverine. Nitroglycerin relaxed the coronary artery preparations under K+-contracture as well as La3+-contracture, but did not relax the colon preparations under K+- and La3+-contracture. Papaverine relaxed both types of smooth muscles under K+- and La3+-contracture. Nifedipine relaxed the coronary artery and the colon preparations under K+-contracture, but did not relax them under La3+-contracture. Propranolol produced the same relaxant effects on both preparations as nifedipine. Furthermore, propranolol concentration-dependently inhibited the calcium-induced contractions of the coronary arterial preparations. The results suggest that propranolol, like nifedipine, may have a calcium antagonistic action in the cell membrane of smooth muscles.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D005260:Female; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D014665:Vasodilator Agents; D007811:Lanthanum; D011433:Propranolol; D011188:Potassium; D002118:Calcium