Catabolism of human very low density lipoproteins in vitro: a fluorescent phospholipid method for monitoring lipolysis.

The catabolism of human plasma very low density lipoproteins (VLDL) by purified bovine milk lipoprotein lipase has been measured in vitro using a fluorescent phospholipid as a method to monitor lipolysis. Dansyl phosphatidylethanolamine (DPE) was incorporated into VLDL to form DPE-VLDL, and the rate of catabolism was followed by measuring the increase in fluorescence at 490 nm after the addition of the enzyme. The studies were performed with VLDL isolated from 20 normal individuals. In addition, the VLDL from 8 mildly obese subjects with primary hypertriglyceridemia (Type IV phenotype) was studied. With this in vitro system and with a constant amount of lipoprotein lipase, the rate of lipolysis did not differ in normal and in these hypertriglyceridemic subjects. Furthermore, there was no correlation between the rates of hydrolysis and the plasma levels of triglyceride or high density lipoprotein cholesterol.