['Previous studies have suggested that endothelin (ET)-1 with its marked vasoconstrictive potency may play a role in the induction of coronary artery spasms. Furthermore, it was demonstrated using in-vitro vessel preparations that the secretion of ET-1 by the vascular endothelium is enhanced in the presence of atherosclerotic alterations. The objective of the present study was to investigate a) the effects of ergometric exercise on ET-1 plasma concentrations in 10 patients with coronary artery disease (CAD) as compared to an age and sex matched control group and b) the modulatory role of the orally administered organic nitrate, pentaerithrityltetranitrat (PETN), in patients with CAD.', '10 male patients with CAD confirmed by coronarography and 10 male healthy controls underwent a bicycle ergometry according to the WHO-standards upt to 125 watts. Venous blood samples for determination of ANP and ET-1 plasma concentrations were drawn in supine position directly before and 5 min after ergometric exercise. Subsequently, patients were randomized and treated for 3 days in a crossover design either with placebo or PETN (150 mg b.i.d.).', 'Basal plasma levels of ET-1 were 6.1 +/- 0.7 pg/ml (patients) and 5.5 +/- 0.6 pg/ml (controls), resp. (n.s.). After ergometric exercise ET-1 plasma concentrations rose significantly (7.3 +/- 0.9 pg/ml; p < 0.05) in the placebo-treated patient group, whereas they remained constant (5.5 +/- 0.7 pg/ml) in the PETN-treated patient group. Blood pressure and heart rate were not modified by the PETN-treatment. ET-1 plasma levels remained unaffected by ergometric exercise in controls.'] Is the exercise-induced increase in plasma levels of endothelin-1 enhanced in patients with atherosclerotic coronary artery disease . Modulation by pentaerithrityltetranitrat ( PETN )?