Lipoprotein receptor activity of peritoneal macrophages from insulin-deficient mice

Summary Binding, uptake and degradation of¹²⁵I-labeled normal very low density lipoprotein(¹²⁵I-n-VLDL) from normal swine plasma and¹²⁵I-labeled β-migrating VLDL (¹²⁵I-β-VLDL) from hypercholesterolemic rabbit plasma by peritoneal macrophages of mice rendered insulin-deficient by streptozotocin (250 mg/kg) were studied. It was found that the amount of binding, uptake and degradation of¹²⁵I-n-VLDL by macrophages from the diabetic mice was 2-fold or 2.5-fold higher than by macrophages from normal mice, resulting from an increase in the binding capacity of VLDL receptors on the macrophages from the insulin-deficient rodents. In contrast, the binding, uptake and degradation of¹²⁵I-β-VLDL by macrophages from diabetic mice were reduced to only about 45 % of normal levels because of a decrease in the number and affinity of the receptors for β-VLDL. These experimental results indicate that n-VLDL is more important than β-VLDL in the pathogenes is of atherosclerosis in insulin-dependent diabetes.