Endotoxin shock in the piglet: beneficial effects of serotonin antagonism

In anaesthetized piglets the intravenous injection of a lethal dose of endotoxin, 0·5 mg/kg, resulted in a progressively evolving deterioration of cardiovascular performance (hypotension, decrease in cardiac output), in an increase in pulmonary vascular resistance and in the death of all animals within 210 min following endotoxin administration. The induced endotoxic shock was without significant influence on serotonin concentration in total blood and on the monoamine content of the duodenal enterochromaffin cells. Pretreatment with two selective 5-HT₂ receptor antagonists resulted in a reduction of the endotoxin-induced increase in pulmonary vascular resistance and in an increase in survival time, suggesting the possible involvement of serotonin in the typical pulmonary vascular changes during endotoxin shock.