Plasma levels of cyclic GMP and endothelin in postmenopausal women with unstable coronary artery disease

Many women with typical anginal chest pain have normal coronary angiograms, which may be due to altered endothelial function. We evaluated the endothe lial markers cyclic GMP (cGMP) and immunoreactive endothelin (ir-ET) regard ing presence of coronary atherosclerosis in women with clinical signs of un stable coronary artery disease (CAD). Plasma levels of cGMP and ir-ET were determined in 118 patients and 84 controls. Ischaemia was evaluated at an e xercise test. Of the patients 20% had normal vessels, 14% insignificant CAD and 66% significant stenosis at coronary angiography. Mean (95% CI) concen tration of cGMP (nmol/l) was higher in patients than in controls (5.05 (4.5 3; 5.58) vs. 3.79 (3.34; 4.23)). Separating patients according to daily int ake of nitroglycerin, only patients with this medication had significantly higher cGMP level (5.73 (4.88; 6.58)), whereas the difference between those without (4.35 (3.76; 4.94)) and controls disappeared. Patients with ischae mia at exercise test had higher cGMP level than those without (6.01 (5.13; 6.88) vs. 4.30 (3.66; 4.94)), even after adjusting for nitroglycerin treatm ent. ir-ET (pmol/l) was lower in patients with normal vessels than patients with coronary atherosclerosis (0.83 (0.78; 0.88) vs. 0.98 (0.92; 1.04)) an d than the control group (0.91 (0.87; 0.94)). The difference between the co ntrol group and patients with atherosclerosis was also significant. Patient s with unstable CAD and long-term nitroglycerin treatment have increased cG MP level. Patients with exercise-induced ischaemia have higher cGMP level t han those without, irrespective of nitroglycerin treatment, which may refle ct a general compensatory mechanism. Patients with normal vessels have low level of ir-ET, indicating different mechanisms for ischaemia/angina in the se patients compared with patients with atherosclerosis.