Vitamin A exerts potential therapeutic effects in the endotoxaemic pig

Pretreatment with an injection of vitamin A has beneficial effects on cardiac and pulmonary functions in normally bred endotoxaemic pigs. The present study was performed in order to elucidate whether the response of an ongoing infusion of E. coli can be modulated by a single injection of vitamin A.

Sixteen healthy (not vitamin A-depleted) pigs were anaesthetized, monitored, mechanically ventilated and subjected to an infusion of E. coli endotoxin (10 micrograms.kg-1.h-1). This infusion resulted within 30 min in a progressive haemodynamic derangement. When the mean pressure in the pulmonary artery was twice the baseline value, vitamin A (460 IU.kg-1) or a corresponding volume of vehicle was injected intravenously. After sacrificing the animals, the right lung was excised and weighed, and biopsy specimens were taken from the left lung for microscopical examination.

Mean arterial blood pressure was significantly less affected (P < 0.01) between the 1st and 6th hour in endotoxaemic pigs treated with vitamin A than in those given vehicle. The mean lung weight in the vitamin A-treated pigs was significantly lower than that in the vehicle group (164 +/- 5.3 vs 199 +/- 19.8 g; P < 0.01). Microscopical examination showed significantly less oedema (0.93 +/- 0.17 vs 2.00 +/- 0.26; P < 0.01) and microatelectasis (0.56 +/- 0.17 vs 1.75 +/- 0.31; P < 0.01) in the vitamin A group. Endotoxaemia was also accompanied by an initial, steep decline in neutrophil counts in all animals; this decrease was significantly less pronounced (P < 0.05) in vitamin A-injected pigs than in the vehicle-injected group. The major difference was a more rapid restitution in the vitamin A group.

Several manifestations of endotoxaemia were expressed less in the vitamin A group. Thus, vitamin A may turn out to be a tool in the management of endotoxaemia.