446 V. BLOOD LIPIDS 



phospholipid, and total lipid, respectively, is proportional in the insulin- 

 treated depancreatized dogs. The averages of the ratios of these constitu- 

 ents to each other are remarkably uniform in the normal and depancreatized 

 dogs. However, there is one marked difference which is quite apparent. 

 The cholesterol fraction present as the ester has completely disappeared in 

 the pancreatectomized insulin-treated dogs. Whereas the combined chol- 

 esterol makes up 23% of the total cholesterol in the blood of normal dogs, 

 it accounts for only 1% in the experimental animals. However, the es- 

 terified cholesterol still comprises approximately 75% of the total chole- 

 sterol in the liver of the insulin-treated operated animals. 578 



The effect of insulin in preventing the hyperlipemia of depancreatized 

 dogs is completely reversed when the animals are fed raw pancreas by 

 mouth. 579 Under such conditions, the values for the several blood lipids 

 were found to be markedly increased above the preoperative level. The 

 ratio of cholesterol ester to total cholesterol was increased from a preopera- 

 tive level of 23% to one of 45%. The response was likewise similar if 

 raw pancreas was added to the diet of the operated dog after the blood 

 lipids had been depressed by previous treatment with insulin alone. When 

 the feeding of the raw pancreas was suspended and the insulin injections 

 were continued, the level of blood lipids rapidly dropped. There is no 

 explanation for this phenomenon; it seems possible that the relatively 

 large intake of cholesterol, phospholipid, and total lipids present in the 

 250 g. of raw pancreas fed daily may have been partially responsible for 

 the increased blood lipid values. Insulin does not alter the concentration 

 of the blood lipids in normal men with adequate glycogen stores. 533,580 

 However, Rony and Ching 581 reported that, although insulin is without 

 effect on the blood lipids of fasting dogs, it is able to inhibit alimentary 

 hyperlipemia in these animals. 



In addition to the depressing effect which insulin exerts on the blood 

 lipids, it will also decrease or completely abolish any existing ketonemia 

 and ketonuria. However, the reaction within the body depends somewhat 

 upon the accompanying nutritional conditions. When carbohydrate re- 

 serves are available, the injection of insulin results in an immediate de- 

 crease in blood ketones, which occurs concomitantly with the oxidation of 

 carbohydrate. 582,583 On the other hand, when the carbohydrate reserves 



578 A. Kaplan and I. L. Chaikoff, J. Biol. Chem., 108, 201-216 (1935). 

 679 I. L. Chaikoff and A. Kaplan, J. Biol. Chem., 112, 155-165 (1935). 

 580 H. U. Hartmann, Biochem. Z., 146, 307-317 (1924). 



681 H. R. Rony and T. T. Ching, Endocrinology, 14, 355-363 (1930). 



682 L. Salomonsen, Am. J. Diseases Children, 40, 718-724 (1930). 



683 M. Somogyi, /. Biol. Chem., HI, 219-227 (1941). 



