Hypertriglyceridemia associated with decreased post-heparin plasma hepatic triglyceride lipase activity in hypoxic rats

Abstract

Exposure of sated rats to 45% N2 in air for 5h increased serum triglyceride levels by 212% over the levels in normoxic rats. This increase in triglyceride levels was accompanied by a decrease in plasma triglyceride hydrolase activity after intravenous injection of heparin. Further fractionation of the activity by inhibition of lipoprotein lipase indicated that the low triglyceride hydrolase activity is mainly due to a reduction in hepatic triglyceride lipase, which is inversely correlated with the serum triglyceride level. The hypoxic exposure decreased the arterial blood [acetoacetate]/[beta-hydroxybutyrate] ratio in the sated rats, which is believed to reflect the oxidation-reduction state in hepatic mitochondria, but did not affect the level of serum enzymes indicative of tissue damage. On the other hand, triglyceride levels did not change during hypoxic exposure in fasted rats. Thus, hypertriglyceridemia in sated rats following exposure to hypoxia may result from impaired removal of circulating triglycerides by hepatic triglyceride lipase located in the sinusoidal surface of the liver.