Effects of the Concentration of Medium Glucose on Glucose Disappearance and Oxidative Metabolism by Liver Slices of Rats

Abstract

Liver slices of Sprague-Dawley rat were incubated with various concentration of 04·glucose in the incubation medium. A constant condition was main· tained by periodic replacement of the incubation medium and gas phase throughout the experimental period, during whichhourly samples were withdrawn and analyzed for glucose disappearance rate, and the rate of oxidation of C14·glucose into CO2, From 32 cases of experiments in which concentrations of C14·glucose in the incubation medium were varied, the following results were obtained. 1. Every metabolic rate vs, concentration curve for glucose disappearance rate, relative specific activity and C02 production rate from 04'glucose represents characteristic diphasic nature as in the process of enzyme reaction, arid approaches to a plateau at the medium concentration of about 150 mg%. 2. A plateau value for glucose disappearance was 65,uM/hr/gm, for RSA, 70% and for CO2 production rate from CI4'glucose, 70,uM/hr/gm. Fractions of glucose disappeared into CO2 or RGD were average 19% for all ranges of glucose concentrations. 3. Km values for enzyme concerned with glucose transport at the cell membrane and oxidative metabolism were 3.33 x 10-4 M/L and 3.62 x 1O-4M/ L respectively. These Km values imply that glucose oxidation in the metabolic pool would be interfered by penetration lag at the cell membrane.