[Effect of endotoxin on plasma angiotensin-converting enzyme in dogs]

We calculated angiotensin converting enzyme (ACE) index (ACE/CO) to exclude the influence of pulmonary perfusion and investigated the relationship among ACE, ACE index, hemodynamic changes in 6 endotoxin dogs. Systemic arterial pressure and cardiac output (CO) decreased significantly after 3 mg.kg-1 of endotoxin administration, but neither pulmonary arterial pressure nor pulmonary arterial wedge pressure changed. Lung wet/dry ratio was higher. Although endotoxin administration caused the pulmonary capillary endothelial damage in this experiment, plasma ACE showed a nonsignificant increase. The main reason may be related to the reduction of surface area of pulmonary capillary endothelial cells caused by the decrease in cardiac output. The increased ACE index lasted for 15 to 90 min and began to return to baseline at 120 min after endotoxin administration. We conclude that ACE index is more useful than plasma ACE as an early marker of the pulmonary capillary endothelial damage induced by endotoxin.