Effects of carbocromene on myocardial oxygen consumption in isolated dog hearts

In isolated empty beating and isovolumetrically working supported dog hearts, the effects of intracoronary administration of the antianginal agent carbocromene (chromonar) and its corresponding acid metabolite on coronary blood flow and myocardial oxygen consumption were investigated. After administration of 1.0 and 2.0 mg of carbocromene per heart, coronary flow increased significantly between 61 (P less than .05) and 155% (P less than .01) in both types of experiments. However, the carbocromene acid did not alter coronary flow. Both compounds decreased with the used doses myocardial oxygen consumption between 18 (P less than .05) and 36% (P less than .05) in empty beating as well as in working hearts. Both agents did not cause significant changes in heart rate and inotropy of the isolated hearts in both types of experiments. It is suggested that carbocromene decreases myocardial oxygen consumption by a direct effect on myocardial oxygen metabolism as is evident from the fact that this decrease is not accompanied by changes in any of the parameters which influence oxygen consumption. This effect of the drug is independent from its coronary vasodilating properties as the metabolite doses not change coronary flow but decreases myocardial oxygen consumption in both types of experiments.