Effects of grisorixin on the distribution of thallium-201 and on the oxidative metabolism in cultured myocardial cells

Previous experiments in the dog and guinea-pig have shown that grisorixin, a monocarboxylic ionophore, can significantly increase the coronary blood flow and the myocardial uptake of 201Tl, as well as have a stimulant effect on the heart. In this study, cultures of myocardial cells were used in order to isolate the cells from the vascular and extracardiac influences so that any ionophorous effect on 201Tl could be evidence. The effects of grisorixin on the oxidative metabolism were simultaneously studied. The activity of the 14CO2 produced by oxidation of [14C]glucose and [14C]octanoate added to the medium of culture and the intra/extracellular ratio of 201Tl concentrations (Tl i/e) were measured. The conclusion is that grisorixin decreases both the intracellular concentration of 201Tl and the fatty-acids oxidation in cultured myocardial cells. The beneficial effects previously observed in vivo were probably the consequence of the strong coronary dilatation and of an indirect stimulation