Effects of gemfibrozil on triglyceride metabolism in Dahl salt-sensitive rats

Hypertriglyceridemia is a common feature of patients with increased blood pressure as well as several rodent models of hypertension. The goal of this study was to evaluate the effects of gemfibrozil on established abnormalities of triglyceride (TG) secretion and TG clearance in the Dahl salt-sensitive rat. Consequently, Dahl salt-sensitive rats received 12 days treatment with gemfibrozil (30 mg/kg/day) or vehicle by p.o. gavage and the following measurements were made: 1) fasting plasma TG levels; 2) TG secretion rate after suppression of TG removal with Triton WR 1339; 3) TG removal rate (half-time of disappearance of prelabeled very low density lipoprotein); and 4) lipoprotein lipase (LPL) activity and mRNA in soleus muscle, fat and liver tissues. Gemfibrozil produced a 50% reduction in fasting plasma TG concentrations, with no effect on TG secretion rate (17 +/- 2 vs. 15 +/- 1 mg/100 g b.wt./hr). The half-time of prelabeled very low density lipoprotein-TG removal was significantly lower in drug-treated animals (3.9 +/- 0.3 vs. 6.1 +/- 0.9 min), and this was associated with a tissue-specific increase in LPL activity in soleus muscle (153 +/- 5 vs. 135 +/- 5 U/g, P < .02). Expression of LPL mRNA, relative to beta-actin mRNA, was similar in both groups of rats. Thus, in this rodent model of hypertension and dyslipidemia, gemfibrozil lowers plasma TG levels by 50% with no effect on TG secretion; the hypotriglyceridemic effect is due mainly to an increase in TG removal rate associated with a post-transcriptional increase in LPL activity in skeletal muscle.