Effect of the Ca2+ antagonist lidoflazine on normoxic and anoxic contractions of canine coronary arterial smooth muscle.

Anoxia augments contractions of isolated canine coronary arteries to 5-hydroxytryptamine and norepinephrine. Lidoflazine inhibits normoxic contractions to both monoamines and the further increases in tension seen with anoxia in rings exposed to 5-hydroxytryptamine; further increases in tension caused by anoxia in presence of norepinephrine were not affected by lidoflazine. These experiments demonstrate that anoxia can cause constriction of large coronary arteries and that lidoflazine depresses both anoxic and normoxic contractions of coronary smooth muscle.