Angiotensin-converting enzyme (ACE) in sepsis

Angiotensin-converting enzyme (ACE) is localized to the luminal surface of pulmonary endothelial cells, where it converts angiotensin I and activates bradykinin. Sepsis may result in endothelial cell dysfunction. We have previously reported that the marked decrease in serum ACE in patients with the Adult Respiratory Distress Syndrome (ARDS) is present only in septic patients. Serum was evaluated in seven baboons made septic by the infusion of live E coli. There was a significant decline in serum ACE from a control value of 41.5 +/- 4.2 to 25.8 +/- 2.2 at 8 h (P less than 0.05), which correlated with the 65 +/- 11 torr decline in mean arterial pressure. There was no change in PaO2. We conclude that sepsis results in marked depletion of serum ACE activity, which corresponds to the decrease in mean arterial pressure, and may reflect reduced bradykinin inactivation.