THE EFFECTS OF INSULIN AND GLYCINE ON HEPATIC GLUCOSE OUTPUT IN NORMAL, HYPOPHYSECTOMIZED, ADRENAL DENERVATED, AND ADRENALECTOMIZED DOGS

Abstract

Direct observations of the effects of insulin (sub-cut.) and glycine (oral) on glucose and lactic acid, in portal, hepatic, and arterial blood were made in normal, hypophysectomized, adrenal denervated, and adrenalectomized animals by the angiostomy technique without anesthesia. Retention or output by the liver is expressed in terms of mg. of substance per 100 cc. of blood. In normal dogs there is a positive correlation between fasting arterial blood sugar level and hepatic glucose output (r = 0.54 in 24 dogs). There is also a correlation showing an inverse relationship between fasting hepatic glucose output and the change in glucose output by the liver 20 mins. after insulin (r =[long dash]0.95 in 12 dogs). Normal dogs react to the oral adm. of 20 g. of glycine by an average increase of 17 mg. in blood sugar and approximately 100% increase in hepatic glucose output (30 mins.). An increased hepatic output of urea lags behind the increase in glucose output. The fasting hepatic glucose output in hypophysectomized animals averages less than 50% of the value for normal dogs, and does not increase during the hypoglycemic stage of insulin action as it does in normal animals. The changes in hepatic glucose output and blood sugar level after glycine is administered to the hypophysectomized dog are comparable to those of the normal animal. The fasting hepatic glucose output of the adrenal denervated dog is suggestively but not significantly lower than in the normal. As in the hypophysectomized prep., insulin does not increase hepatic glucose output. These animals uniformly show insulin shock about 1 hr. after inj. Adrenalectomized dogs maintained on a high Na low K diet exhibit blood sugar and hepatic glucose output values comparable to those of adrenal denervated dogs, and the changes after insulin inj. are similar.