The effect of in vitro captopril and angiotensin II on plasma renin activity.

Samples of plasma from ten normotensive volunteers and ten hypertensive patients were assayed for plasma renin activity before and after the addition of either captopril or captopril and angiotensin II. The study was repeated after treating portions of the same specimens with trypsin, to activate the inactive renin component. The results indicate that inactive renin is not converted to the active form by captopril in vitro, nor does the addition of angiotensin II inactivate the active form. These data are consistent with the in vivo findings that changes in active and inactive renin occur independently under conditions of challenge by captopril or angiotensin II analogues.