The hemodynamic, anti-ischemic, metabolic, and neurohumoral effects of the phosphodiesterase inhibitor enoximone were investigated in 17 patients (mean age 58 +/- 2 years) with coronary heart disease as established by coronary angiography and positive exercise tests after i.v. application of 0.75 mg/kg body weight. Whereas administration of enoximone resulted in a significant increase in heart rate from 75 +/- 17 to 83 +/- 14 per minute (p less than 0.01), exercise heart rate, blood pressure and myocardial oxygen consumption did not change significantly (p greater than 0.05). At rest, enoximone led to a significant decrease of mean right atrial pressure from 5.7 +/- 2.3 to 3.8 +/- 1.2 mm Hg (p less than 0.01). During exercise there was a significant fall in pulmonary pressure (PAm from 40 +/- 7 to 24 +/- 7 mm Hg, p less than 0.001; PCm from 24 +/- 7 to 14 +/- 6 mm Hg, p less than 0.001) caused by preload reduction and concomitant inotropic increase; there was also a significant rise in cardiac output from 12.7 +/- 5 to 13.8 +/- 5 mm Hg (p less than 0.01) and a decrease of ST-segment depression from 1.97 +/- 0.76 to 0.53 +/- 0.51 mm (p less than 0.001). With improved peripheral and probably coronary blood flow, a concomitant decrease of the metabolic ischemic markers was detected during exercise (potassium 4.44 +/- 0.29 vs. 4.31 +/- 0.30 mval, p less than 0.05; lactate 19 +/- 9 vs. 18 +/- 7 mg/dl; pH 7.28 +/- 0.27 vs. 7.36 +/- 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)