Endotoxin increases vasopressin release independently of known physiological stimuli

Abstract

Plasma vasopressin (AVP) increased after endotoxin administration in freely behaving unanesthetized rats. The factors that mediated this vasopressin response were determined. Endotoxin (150 .mu.g/kg i.v.) elicited a significant increase in plasma AVP concentration. This response was accompanied by unchanged plasma osmolality, hypotension, increased hematocrit (reflecting decreased plasma volume), hypothermia and hyperglycemia. Pretreatment with the prostaglandin synthesis inhibitor, indomethacin (5 mg/kg s.c.), had no effect on the vasopressin response to endotoxin but abolished or significantly attenuated the changes in blood pressure, hematocrit, temperature and plasma glucose while leaving plasma osmolality unaltered. Endotoxin stimulates vasopressin secretion into plasma independently of changes in plasma osmolality, systemic blood pressure, plasma volume, body temperature or plasma glucose. Vasopressin responses to endotoxin are not mediated by prostaglandins, whereas prostaglandins do play a role in endotoxin''s effect on blood pressure, plasma volume, temperature and plasma glucose.