RESUMO
In erythrocytes from diabetic rats the generation of radioactive metabolites from 3H- or 14C-labeled D-glucose occurs at a lower rate than in cells from control animals, while the total production of L-lactic acid is the same in both cell types. The radioisotopic anomaly is not corrected by agents causing phosphofructokinase activation and is not attributable to interference of metabolites generated from either glycogen or 2,3-diphospho-D-glycerate. It is mimicked by preincubating the erythrocytes at a high concentration of D-glucose and suppressed in diabetic rats treated with insulin in order to lower the blood glucose concentration prior to sacrifice. These findings suggest isotopic dilution of the 3H- or 14C-labeled tracer by endogenous unlabeled D-glucose. The influence of factors such as the concentration of erythrocytes in the incubation medium, the concentration of extracellular D-glucose, and the length of incubation upon radioactive metabolic variables is also compatible with the postulated phenomenon of isotopic dilution.
