We studied on the inhibitory effects of reduced glutathione on the intestinal secretion induced by four kinds of bacterial enterotoxins in bioassay. Escherichia coli ST(heat stable enterotoxin)-induced intestinal secretion was completely
inhibited
by
reduced glutathione. The intestinal secretions induced by cholera enterotoxin, Escherichia coli LT(heat labile enterotoxin) and Yersinia enterotoxin were also significantly inhibited by reduced glutathione.
In addition, Escherichia coli ST-induced intestinal secretion was also inhibited by thiol-compounds (thiouracil, thiosalicylate and cysteine) and their inhibitory effects were marked like the effect of reduced glutathione. But radical
scavengers(allopurinol, uric acid and ascorbic acid) did not inhibit Escherichia coli ST-induced intestinal secretion. Diethyldithiocarbamate and aminotriazole, which are inhibitors of superoxide dismutase and catalase respectively, did not
influence
the ST-induced intestinal secretion either.
The mixture of Escherichia coli ST and reduced glutathione lost its enterotoxic activity in infant mouse assay, but Escherichia coli ST and PBS mixture did not. Subcutaneous injection of reduced glutathione also indicated that this drug would
inhibit
intestinal secretion not by enzyme inactivation(i.e, guanylate cyclase) but by direct inactivation of Escherichia coli ST.
All these results suggest that the inhibitory effect of reduced glutathione on several bacterial enterotoxins-induced intestinal secretion is due to direct interaction between enterotoxins and reduced glutathione, probably thiol-disulfide
exchange.
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