Metabolism of glutathione. V. An effect of insulin.

Glutathione and the products of its hydrolysis were determined by methods of this laboratory (I) ; glucose was determined by the method of Somogyi (2) and of Nelson (3). Rats were anesthetized with ether, blood was removed from the vena cava, and other tissues were removed, weighed, and immediately homogenized with cold 5 per cent trichloroacetic acid (about 10 ml. per 1 gm.), filtered, and the filtrates used in the analyses. Glutathione added to homogenates in water was recovered in yields of 98 to 105 per cent by this procedure. Total carbohydrate of the liver was determined as glucose following hydrolysis of the tissue with 0.6 N HCl in the autoclave. Male rats of the Sprague-Dawley strain, 200 to 250 gm., and adult rabbits, males and females, were fasted 16 hours before the start of an experiment. It was found that in the series of rats receiving 5 units of insulin the content of glutathione of the liver was decreased in a straight line relationship with time for periods of about 90 minutes. The mean values were controls, 128 mg. per cent; at 30 minutes, 100 mg. per cent; at 60 minutes, 72 mg. per cent; at 90 minutes, 40 mg. per cent; and at 120 minutes, 22 mg. per cent (standard error of each point about f20 mg. per cent, of the line f9 mg. per cent). The tissues of paired groups of animals were analyzed at 120 minutes so that a comparison of other tissues could be made; these results are given in Table I. It is apparent that the changes in liver tissue were highly significant, but significant changes in other tissues