INVOLVEMENT OF ASPARTATE GLUTAMATE ANTIPORTER IN UNCOUPLING EFFECT OFFATTY-ACIDS IN HEART-MITOCHONDRIA/

Earlier it was shown that fatty acid-induced uncoupling in liver mitoc hondria is suppressed by the substrates of the aspartate/glutamate ant iporter (V. N. Samartsev, A. V. Smirnov, I. P. Zeldi, O. V. Markova, E . N. Mokhova, and V. P. Skutachev (1997) Biochim. Biophys. Acta, 1319, 251-257). In this study it is shown that in heart mitochondria aspart ate, glutamate, and diethyl pyrocarbonate do not affect oxygen consump tion and membrane potential in the presence of laurate at pH 7.4. Thes e compounds have a weak (versus carboxyatractylate) coupling effect at pH 7.0. This effect is manifested only in the presence of carboxyatra ctylate, magnesium, and phosphate in the incubation medium. It is sugg ested that these tissue-specific effects are due not only to the speci fic characteristics of aspartate/glutamate antiporter, but also to the differences in the content of endogenous metabolites in heart mitocho ndria.