Activity of serum angiotensin converting enzyme in septic pigs treated with intrapulmonary corticosteroid

To evaluate serum angiotensin converting enzyme activity (S-ACE) in sepsis, its association with haemodynamics and pulmonary function, and the influence of intrapulmonary corticosteroid on its activity in serum.

Randomised, blind, placebo controlled experiment.

Trauma research laboratory.

Sixteen juvenile pigs.

Mechanical ventilation and continuous light anaesthesia. Brief infusion of live Staphylococcus aureus (4 x 10(10) colony forming units) followed by inhalation of nebulised beclomethasone dipropionate 50 micrograms/kg (n = 8) or placebo (n = 7) 30 and 360 minutes after the start of the septic challenge.

S-ACE activity, vascular pressures, lung mechanics, arterial oxygen tension, and global oxygen extraction were measured and calculated at regular intervals. One animal was withdrawn because of pulmonary arterial hypertension at the start of the experiment. The 15 remaining pigs were studied for 12 hours. The septic challenge induced a significant but transient increase in S-ACE activity in 13 animals (mean (SEM) +0.19 (0.06) mu kat/l). There were no significant differences in S-ACE between the groups. Terminal S-ACE correlated with oxygen extraction (r = -0.76, p < 0.01), mean arterial pressure (r = 0.69, p < 0.01), arterial oxygen tension (r = 0.59, p < 0.05) and change in lung/thorax compliance (r = 0.63, p < 0.02).

S-ACE activity increases in response to a Gram positive septic challenge. This is followed by a gradual decline which reflects to some extent the degree of septic lung injury. S-ACE activity is not influenced by intrapulmonarily administered corticosteroid.