Acute effects of vitamin A on the kinetics of endotoxin in conscious rabbits.

Abstract

Vitamin A reduces the pathophysiological effects of endotoxin in animals, but the mechanism and the lowest effective dose are not clear. An intravenous bolus of endotoxin 20 microg. kg(-1) was given to 30 rabbits. In 10 of them, 1000 IE. kg(-1) retinyl palmitate was injected intravenously 1 h before the endotoxin and in another 10 rabbits 1 h after the endotoxin. A one-compartment open model was fitted to the time-concentration profile of endotoxin in plasma. The half-life of endotoxin was half as long when vitamin A was given for prophylaxis (median 35 min) and for treatment (33 min) than in the controls (67 min; p < 0.004). The plasma concentrations of immunoglobulin G and M endotoxin-core antibodies, the leucocyte count and the acid-base balance did not differ between the groups during the experiment, but the pyrogenic reaction was more pronounced in the controls. A fairly low dose of vitamin A reduced the half-life of endotoxin.