In guinea-pig Langendorff hearts, Na-salicylate (1.9, 3.8 and 7.6 mmol/l) concentration-dependently reduced the contractile force (--9.1, --51.0 and --75.1%, respectively) and the coronary resistance. The influence of the uncoupling agent 2.4-dinitrophenol (0.02 mmol/l) was comparable to that of the largest concentration of Na-salicylate. From the three congeners of Na-salicylate that were tested, only 3.5-diiodosalicylate (0.03 mmol/l) reduced the contractility whereas Na-benzoate (42 mmol/l) and m-iodobenzoate (1.2 mmol/l) were inactive. These results suggest that the cardiac effects of salicylate-like compounds in vitro are caused by an uncoupling of the oxidative phosphorylation.
