Effects of glucose on the metabolization of fructose and glycerol by isolated adipocytes from rat.

Abstract

Isolated white fat cells were incubated in medium containing (1 'C)-fructose (UL), supplemented with either 1 or 5 mM fructose, in the presence or absence of 5 mM glucose. The utilization of fructose for the formation of CO,, fatty acids or glyceride glycerol was very much dependent on its concentration in the medium. It was significantly inhibited by glucose only at fructose concentration of 5 mM. When the cells were incubated in the presence of (l-14C) glycerol, fructose produced a significant increase in the conversion of the tracer to CO,, fatty acids and glyceride glycerol, while glucose produced an increase in the formation of both CO, and fatty acids, but a significant decrease of glyceride glycerol from the same labelled precursor. Glucose causes the effects of fructose, enhancing the uptake of labelled glycerol by the cells, to disappear.

Se incubaron adipocitos aislados de rata en medio conteniendo fructosa-U-C'", suplementado con fructosa 1 6 5 mM, en presencia o en ausencia de g]ucosa 5 mM. La formaci6n de CO,, acidos grasos o glicerol de gliceridos a partir de fructosa era dependiente de la concentraci6n de substrato, siendo inhibida por la glucosa solamente a concentraciones 5 mM dt:: fructosa. Cuando las celulas se incubaron en presencia de glicerol-1-C'\ la fructosa produjo un aumento significativo de la conversion de! trazador a CO,, acidos grasos y glicerol de gliceridos. Sin embargo, la glucosa produjo un aumento de la formaci6n de C02 y acidos grasos, pero un descenso significativo de la formaci6n de glicerol de gliceridos, a partir de! mismo precursor radioactivo. La glucosa produjo la desaparici6n de! efecto de la fructosa aumentando la captaci6n de glicerol radioactivo por !as celulas.