Decreased Citrate Synthesis by Lymphocytes from Alloxan-Diabetic Rat

Abstract

Summary

The effect of alloxan-diabetes on the ability of rat splenic lymphocytes to synthesize citrate has been studied. Untreated and insulin-treated diabetic as well as normal rats were used for these studies. For the in vivo studies, [l-¹⁴C]labeled acetate was injected into rats intravenously, 15 min after an intravenous injection of mono-fluoroacetate. The animals were sacrificed 30 min later and the amount of labeled citrate in the blood and spleen of the rats was determined. The splenic tissue of untreated diabetic rats contained significantly decreased amounts of labeled citrate as compared to insulin-treated and control rat spleens. No such differences were observed in the bloods of the three groups.

In another study, the splenic tissue of diabetic rats was incubated in vitro with tracer quantities of labeled acetate and substrates. The diabetic rat spleen was found to produce significantly decreased amounts of citrate in contrast to the spleen of normal or insulin-treated rats.

A method to isolate splenic lymphocytes has been described. The isolated splenic lymphocytes from the various groups of rats were lysed and the cell suspensions were incubated with labeled and unlabeled acetyl CoA and oxaloacetate. The labeled citrate synthesized by the diabetic rat lymphocyte suspensions was found to be significantly lower than that synthesized by suspensions from normal or insulin-treated rats. These studies indicate that splenic lymphocytes from untreated diabetic rats exhibit decreased ability to synthesize citrate.