Objective: To define the profiles of endothelin (ET), both big ET and active 21 amino acid ET (ET 1-21) in the plasma and peritoneal cavity of rats with peritonitis.
Design: Open laboratory study.
Setting: University hospital, Norway.
Material: 170 adult male Wistar rats.
Interventions: Lethal peritonitis was induced by making a 4 mm caecal perforation.
Main outcome measures: Mortality, together with concentrations of total ET, ET 1-21 (measured by two radioimmunoassays), bacteria, endotoxin, tumor necrosis factor (TNF), interleukin 6 (IL-6), and lactate at baseline, two hours, and then four-hourly intervals for 24 hours.
Results: ET reached its maximum at 8 hours, and had returned to baseline after 24 hours. In the first phase of septicaemia there was more big ET than ET 1-21, but the proportions had equalised by 8 hours. There were higher concentrations of both big ET and ET 1-21 in peritoneal fluid than in plasma.
Conclusions: In rats with peritonitis the profiles of big ET and ET 1-21 closely followed mortality, and blood concentrations of bacteria, endotoxin, TNF, IL-6, and lactate.