['The angiotensin-converting enzyme (ACE) DD-genotype is associated with increased plasma and myocardial ACE-activity. The influence of the ACE insertion/deletion (I/D) polymorphism on the effects of ACE-inhibition on vascular responses has not been previously described.', 'In the randomised, double-blind QUinapril On Vascular ACE and Determinants of Ischemia Study (QUO VADIS), 149 patients undergoing coronary bypass surgery were randomised to receive either the ACE inhibitor, quinapril, or placebo. In 82 patients, we obtained ACE-genotype, and measured vascular responses to angiotensin II (Ang II) in left internal mammary arteries.', 'In the placebo group, the mean maximal vasoconstriction to Ang II was significantly lower in patients with the DD-genotype than in those with the ID/II genotype (36.2+/-5.11% [n=13] vs. 55.6+/-4.57% [n=25]; p=0.01). In the quinapril group, the mean maximal vasoconstriction to Ang II was similar between DD- and ID/II-genotype (59.6+/-9.19% [n=8] vs. 57.7+/-4.07% [n=35]; p=0.85).'] Do vascular effects of quinapril completely depend on ACE insertion/deletion polymorphism?