Angiotensin-converting enzyme inhibitor inhibits dehydration-enhanced fever induced by endotoxin in rats

It has been reported that a host develops a marked fever under dehydrated c onditions compared with normally hydrated conditions (11). The present stud y was carried out to investigate whether ANG II is involved in the enhancem ent seen in dehydrated rats of the fever induced by bacterial endotoxin. Th e results showed that intravenous injection of bacterial endotoxin produced a fever in dehydrated rats (rats deprived of water for 24 h) that was sign ificantly greater than that seen in normally hydrated rats. In contrast, de hydration had no effect on the fever induced by intravenous interleukin-1 b eta (IL-1 beta). Under dehydrated conditions, the enhanced endotoxin- induc ed fever was significantly inhibited by the angiotensin-converting enzyme i nhibitor lisinopril, but the IL-1 beta fever was not. These results suggest that the dehydration-induced enhancement of endotoxin fever is due, at lea st in part, to the action of ANG II, which elicits an increased production of pyrogenic cytokines such as IL-1.