Lipoprotein lipase in rats sensitized to endotoxin by surgical trauma

Abstract

Rats are sensitized to the lethal effects of endotoxin 24 hr after the implantation of intravascular catheters. In view of this observation, selected metabolic and hemodynamic changes were compared in conscious rats subjected to endotoxic shock with and without prior surgical cannulation of a carotid artery and external jugular vein (NS = nonsurgical; S = surgical). Emphasis was placed upon alterations in heart and adipose tissue lipoprotein lipase (LPL) activity due to surgical trauma and endotoxic shock. Only one-tenth the endotoxin dose required to cause death in 50–70% of 24 hr fasted NS rats (2.0 mg/100 g) was necessary to produce a similar effect in S rats 24 hr post-surgery (0.2 mg/100 g). Mean arterial blood pressure decreased from 128 ± 5.3 to 76 ± 8.2 mm Hg by 1 hr postendotoxin in the S group. Blood glucose levels were increased 95 and 57% within the first 2 hr after endotoxin in NS and S rats, respectively. Plasma free fatty acid (FFA) content was reduced 1.5 hr postendotoxin and returned to control levels by 4 hr in S rats. NS rat plasma FFA content remained reduced through the fourth hour. S rats responded to endotoxin with an increased plasma triglyceride concentration at 4 hr while no significant change was evident in NS rats. Heart LPL activity was significantly increased in S rats compared to NS rats while endotoxin administration reduced myocardial LPL activities in both groups. Neither surgical trauma nor endotoxic shock affected adipose tissue LPL activity. The decrease in myocardial LPL activity in endotoxic shock may represent a specific effect of endotoxemia on this tissue's capability to clear triglycerides.