The effect of dietary and sulfur compounds in alleviating 3-methylindole-induced pulmonary toxicity in goats.

The present experiment was designed to determine the effect of tissue concentrations of glutathione (GSH) and GSH-S-transferase activity on 3-methylindole (3MI)-induced pulmonary toxicity in vivo. Forty goats were given high protein, normal protein, high cysteine, high sulfate or diethyl maleate (DEM) to vary tissue concentrations of GSH before i.v. infusion of 3MI. The severity of lung lesion was scored. Tissue GSH concentration, GSH-S-transferase activity and cytochrome P-450 content were measured. Compared to goats fed normal protein diet, high cysteine or high sulfate increased the tissue GSH levels and reduced the severity of the lung lesion induced by 3MI. Pretreatment with DEM, by which the tissue GSH was depleted, increased the severity of 3MI-induced lung lesion. Tissue GSH-S-transferase activity was not changed. These results indicate that the tissue concentration of conjugating agents play an important role in 3MI-induced lung disease.