Angiotensin-converting enzyme inhibition augments coronary release of tissue plasminogen activator in women but not in men.

The renin-angiotensin system regulates the vascular fibrinolytic balance. In the human forearm vasculature, angiotensin-converting enzyme (ACE) inhibitors (ACE-Is) increase the release of t-PA through endogenous bradykinin. We tested the hypothesis that ACE inhibition and sex modulate the endogenous coronary release of tissue plasminogen activator (t-PA) in hypertensive patients. Seventy-three patients underwent diagnostic coronary angiography and had normal coronary angiograms. Thirty-three patients (21 men and 12 women) were treated with imidapril (5 mg/day) for 4 weeks (ACE-I group), and 40 (23 men and 17 women) were not treated with ACE-I (non-ACE-I group). All of the women were postmenopausal. Coronary blood flow in the left anterior descending artery was evaluated by measuring Doppler flow velocity. Net coronary t-PA release was determined as (coronary sinus-aorta gradient of t-PA)x(coronary blood flow)x[(100-hematocrit)/100]. Age, arterial pressure, heart rate, lipid levels, coronary flow, and the plasma level of t-PA at either aorta or coronary sinus were comparable among the 4 groups. In women, net t-PA release in the ACE-I group was significantly higher than that in the other groups (P<0.05; man non-ACE-I group: 1.4+/-2.6 ng/mL; woman non-ACE-I group: 1.4+/-3.1 ng/mL; man ACE-I group: -1.8+/-2.8 ng/mL; woman ACE-I group: 14.8+/-3.6 ng/mL). Correction for smoking status gave similar results. There was a significant negative correlation between serum ACE activity and coronary t-PA release in women (r=-0.38; P<0.05) but not in men. ACE inhibition increases coronary release of t-PA in women but not in men.