Dissociation Between Plasma Triglyceride Concentration and Tissue Lipoprotein Lipase Deficiency in Insulin-deficient Rats

Insulin deficiency was produced by streptozotocin in young (5-6 wk old) male rats, and measurements were made of plasma triglyceride and glucose concentrations and of lipoprotein lipase (LPL) activity of adipose tissue (epididymal) and muscle (gastrocnemius and soleus). Rats with streptozotocin-induced diabetes underwent a significant reduction in adipose tissue LPL activity (both total and heparin releasable), but the fall in LPL activity in these rats bore little relationship to their rise in plasma triglyceride concentration. Furthermore, muscle LPL activity was essentially unchanged in diabetic rats. Qualitatively similar changes were observed when measurements were made at either 8 a.m. (after the normal evening access to food) or 2 p.m. (6 h after food withdrawal). It is concluded that the hypertriglyceridemia that occurs secondary to insulin deficiency is not a simple function of decreased tissue LPL activity.