[Changes of angiotensin II and angiotensin-converting enzyme in cor pulmonale with respiratory failure]

Angiotensin II (ATII), angiotensin-converting enzyme (ACE) and plasma renin activity (PRA) were measured by radioimmunoassay and fluorometry in 55 cases of cor pulmonale with type II respiratory failure, 48 healthy people and 46 COPD patients.

1. The concentration of ATII in respiratory failure group was higher than that in the healthy people and in the COPD patients. The activity of ACE was lower and PRA was higher in the respiratory failure group than those in the other groups. 2. ATII in the dead was higher than that in the remittent. 3. After oxygen treatment, ATII of the patients with PaO2 greater than 8.0 kPa was lower than that of the patients with PaO2 less than 8.0 kPa, but ACE and PRA of the former were lower than those of the latter. 4. ATII and ACE of the respiratory failure group were closely related to PaO2. It was concluded that during hypoxemia one of the responses to high ATII in the human body was the decrease of ACE. But both the increase of PRA and the insufficient decrease of ACE in the patients with respiratory failure enhance the concentration of ATII. Also the concentration of ATII was related to the prognosis of the patients, and merely supplying the patient with oxygen cannot restore normal ATII. So, in addition to oxygen treatment, it is significant to inhibit PRA and ACE and use ATII as an indicator while dealing with cor pulmonale with cardiac and respiratory failure.