Adenosine triphosphate alters the selenite-induced contracture and negative inotropic effect on cardiac muscle contractions

Selenium is known to play an important role in the physiology of many diffe rent cell types and extracellular application of selenite causes cellular d ysfunction in many different types of tissues. In a previous study, we have shown that in rat ventricles, sodium selenite (greater than or equal to1 m M) caused an increase in the resting tension and a decrease in contractile force, in a time-dependent manner. In the present study, we have shown that sodium selenite caused a contracture state both in Langendorff perfused he arts and isolated papillary muscles. We also showed that the application of extracellular ATP (0.1 mM) markedly reduced this detrimental effect of sod ium selenite on ventricular contraction in Langendorff perfused hearts and delayed it in isolated papillary muscle preparations. In contrast, isoprote renol (0.1 muM) did not seem to influence this action of sodium selenite in papillary muscle preparations. Possible reasons for this protective effect of ATP to selenite-induced contracture are also discussed.