Angiotensin II formation in human vasculature after chronic ACE inhibition: A prospective, randomized, placebo-controlled study

The QUO VADIS (the effects of QUinapril On Vascular Ace and Determinants of ISchemia) study was a randomized, double-blind, placebo-controlled trial designed to evaluate the effects of long-term angiotensin-converting enzyme (ACE) inhibition on angiotensin II formation in human vasculature. Patients (n <187) scheduled for coronary artery bypass surgery used study medication 27 +/- 1 days before surgery. Segments of internal mammary arteries were exposed to increasing doses (0.1 nM-1 mu M) of angiotensin I and II in organ baths. The rate of local angiotensin II formation is a function of the reciprocal of the difference between the pEC(50)'s of the dose response curves to angiotensin I and II (-log/mol) and of the area between the curves (units). Quinapril (40 mg) and captopril (3x50 mg) similarly and significantly reduced mean blood pressure compared with placebo (p = 0.04). Difference between pEC(50)'s was 0.90 +/- 0.08 in quinapril patients compared with 0.60 +/- 0.08 for placebo (p