Physiological Significance of the Secretion of Endogenous Insulin into the Portal Circulation: V. The Quantitative Importance of the Liver in the Disposition of Glucose Loads

Abstract

The quantitative importance of the liver in the disposition of glucose loads was studied in eleven dogs by ex-amining the capacity of the liver to take up glucose during the in-fusion of graded loads of glucose varying from 53 to 1,037 mg. per min. Dogs with portacaval shunts were used to permit measurement of net hepatic rather than splanchnic glucose balance. The data indicate that, at all levels of glucose administration, the liver plays a quantitatively significant role in disposing of the infused loads. The greater the glucose load, the greater the amount of glucose disposed of by a change in net hepatic glucose balance. With large loads not only did hepatic glucose output cease, but the liver extracted in excess of 200 mg. of glucose per minute from the perfusing blood, resulting in a net hepatic glucose conservation of as much as 13.5 gm. per hour. With small glucose loads averaging 70.5 mg. per minute, the liver accounted for the disappearance of 53.7 and the peripheral tissues for 46.3% of the infused load. When large loads varying from 447 to 1,037 mg. per minute were administered, no less than 24.4% and an average of 29% of the utilized load disappeared from the glucose pool as a consequence of a change in hepatic glucose balance.