Delayed Removal of ¹²⁵I-Labeled Very Low Density Lipoprotein from Plasma of Rats with Insulin-Deficient Diabetes Mellitus

Summary

The present studies demonstrate that the removal rate of exogenously labelled ¹²⁵I-VLDL-protein is prolonged when total serum from insulin-deficient rats combined with isolated ¹²⁵I-VLDL is injected into normal recipient rats (6.8±0.7 vs 4.2±0.4 min; p < 0.01), but not when ¹²⁵I-VLDL-protein is isolated and injected alone (4.2±0.8 vs 4.3±0.8 min). Furthermore, the present studies demonstrate that when isolated ¹²⁵I-VLDL-protein is recombined with either VLDL-free (d > 1.006 g/ml), or lipoprotein-free serum (d > 1.215 g/ml) from insulin-deficient rats, the defect in removal rate of VLDL-protein observed in total serum is reestablished (¹²⁵I-VLDL + VLDL-free serum from insulin-deficient rat vs that from normal rat: 7.6±1.2 vs 4.6±0.7 min, p < 0.05; and ¹²⁵I-VLDL + lipoprotein-free serum from insulin-deficient rat vs that from normal rat: 6.4±0.7 vs 4.1±0.4 min, p < 0.01). These data suggest that a factor or factors exist in lipoprotein-free serum of insulin-deficient rats which interfere with the normal removal of ¹²⁵I-VLDL. Since we have previously demonstrated a prolongation in the removal rate of endogenously labeled VLDL-³H-TG, the defect in removal of VLDL from the plasma of insulin-deficient rats appears to include both the lipid and protein moieties of the VLDL particles.

Key words

Streptozotocin-Induced Diabetes - VLDL Free Plasma - Lipoprotein Free Plasma