VARIATIONS IN THE ANGIOTENSIN-CONVERTING ENZYME IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE AND CHRONIC RESPIRATORY INSUFFICIENCY

Maintained hypoxia has been reported to induce inactivation of the Ang iotensin Converting Enzyme (ACE). Variations have also been observed i n patients with chronic obstructive pulmonary disease (COPD) who have chronic hypoxemia and loss of the vascular endothelium. Objectives: 1) to determine serum ACE activity in patients with COPD treated with an d without continuous ambulatory oxygen therapy (CAOT); 2) to verify wh ether there is a correlation between ACE and any hematological, spirom etric or gasometric parameter. Methods: fifty-eight patients fulfillin g clinical and spirometric parameters of COPD were studied. Patients w ere assigned to two groups of therapy: A) Group A, without Continuous Ambulatory Oxygen Therapy (CAOT): 31 males and 1 female (mean age: 64. 8+/-6.52). B) Group B (with CAOT): 23 males and 3 females (mean age ye ars: 63.76+/-8 years). The following procedures were performed: spirom etry, gasometry, blood chemistry, and serum ACE measurements by means of a radioenzymatic assay. The Student ''t'' test with the Bonferroni correction and Pearson regression analysis were used for the statistic al analysis. Results: significant differences were observed for ACE va lues between Group A and Group B: 42.81+/-11.30 vs. 33.40+/-9.43 mumol /min/l, with a p value of 0.001, and also between Group B and referenc e values: 33.40+/-9.43 vs. 39.70+/-9.65 mumol/min/l, with a p value of 0,002. No differences were observed between Group A and reference val ues. No correlations wer found between ACE and any of the variables st udied. Conclusions: ACE was not decreased in all patients with COPD. A CE was decreased only in patients with COPD and respiratory insufficie ncy requiring CAOT and with advanced disease. This results can be corr elated with changes in vascular endothelium, pulmonar parenchyma and m etabolism. It could be a marker of poor prognosis or advanced disease.