Contraction of isolated porcine coronary arteries is inhibited by high concentrations of propranolol.
Isometric tension responses of isolated porcine coronary artery rings were studied in the presence of concentrations of propranolol higher than those necessary to block effects mediated by beta-adrenergic receptors. Propranolol (50-300 microM) inhibited contractions induced by 30 mM KCl and by histamine, norepinephrine, and acetylcholine in a concentration-dependent, noncompetitive fashion. The (+) propranolol isomer and the racemic mixture were equipotent inhibitors of contraction. Propranolol inhibition was partly reversed by increased extracellular Ca++. These effects of propranolol thus appeared to be independent of beta-blockade and could be relevant to some of the drug's observed but still unexplained in vivo actions.
Carey
E L
EL
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
Robertson
D
D
Wells
J N
JN
Robertson
R M
RM
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D006632:Histamine / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology*; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects*
D006633:Histamine Antagonists; D006632:Histamine; D011433:Propranolol; D000109:Acetylcholine; D009638:Norepinephrine