Active and inactive renin after captopril (SQ 14225) administration in hypertensive patients

The changes in active and inactive renin after oral administration of captopril (SQ 14225) were studied in 29 hypertensive patients. Inactive renin was calculated as plasma renin activity (PRA) after cold storage (total renin) minus PRA before cold storage (active renin). The patients were divided into 2 groups, responders and non-responders, according to the response of active renin to captopril. In 9 responders, the active renin increased markedly, while the inactive renin decreased. On the other hand, in 20 non-responders, both renin activities increased only slightly. Total renin increased markedly in responders; it increased in much smaller degree but significantly in non-responders. These data suggest that captopril promotes the conversion of inactive renin to active one and augments the renin release as a whole.