Study on the Mechanism of Endogenous Hypertriglyceridemia

From the Aspect of Post-Heparin Lipolytic Activity

Abstract

The aim of present study is to attempt to elucidate the mechanism of endogenous hypertriglyceridemia and to classify them by means of post-heparin lipolytic activity (PHLA) and immuno reactive insulin (IRI) assay. PHLA was measured in 28 high and 35 normal triglyceride subjects by modification of Fredrickson's method, in which Triolein, Tricaprylin and Ediol were used as substrates. PHLA values were found to be not significantly different between high and normal triglyceride groups. However, PHLA×10^-3/TG pool, which indicate the lipolytic activity per circulating plasma triglyceride content, were significantly reduced in high triglyceride group. The possibility appeared to exist that the activity may be influenced independently regarding two substrates by glucose loading only in high triglyceride subjects. Hypercholesterolemia and abnormality of glucose tolerance in these subjects seemed to have no relation to PHLA under the series of present investigation, but α-lipoprotein concentration correlated significantly with PHLA×10^-3/TG pool. Based on these findings high triglyceride subjects can be classified from the aspects of regulatory mechanism into three categories, 1) overproduction type 2) impaired removal type 3) combined type, and each incidence under present investigation were 0/24, 11/24, 13/24 respectively. Most of Type IV subjects were found to belong to impaired removal type.
Furthermore, the effects of high fat and high carbohydrate diet on PHLA of 12 normal and high triglyceride subjects were studied. PHLA values appeared to be increased following high fat feeding, which was accompanied with the decrease of triglyceride in serum and in very low density lipoprotein.