A PHARMACOLOGICAL INVESTIGATION ON A POSSIBLE CALCIUM ANTAGONISTIC ACTION OF PROPRANOLOL

  • 1 January 1983
    • journal article
    • research article
    • Vol. 262  (1) , 99-108
Abstract
The mechanisms of smooth muscle relaxant effects of propranolol were investigated. The relaxant effects of the drug on K+ contracture or 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. Propranolol concentration-dependently inhibited the Ca-induced contractions of the coronary arterial preparations. Propranolol, like nifedipine, may have a Ca antagonistic action in the cell membrane of smooth muscles.