Abstract
The effect of an agent that lowers the taurine concentration of various tissues, guanidinoethane sulfonate (GES), on the activities of enzymes involved in sulfur amino acid metabolism in the tissues of rats fed a taurine-free puritied diet was evaluated. Rats given 1% GES in drinking water profoundly decreased taurine concentration in various tissues. GES slightly but significantly increased the concentration of glutathione in liver, kidneys, and heart. The drug caused decreases in the hepatic activities of cysteine dioxygenase and cysteinesultinic acid decarboxylase which are involved in a metabolic pathway for the conversion of cysteine to taurine. However, the renal and brain cysteinesulfinic decarboxylase activities were not affected by the drug. This drug did not change the activities of cystathionine synthase and γ-glutamyIcysteine synthetase in the liver and kidneys. GES treatment slightly increased the renal but not the hepatic aspartate aminotransferase activity. The depression of taurine synthesis in the liver may be one factor accounting for the potency of this drug to reduce taurine concentration in tissues.
