As an agent potentially capable of inducing ischemia in patients with coronary artery disease, dopamine administered intravenously was evaluated as a pharmacologic stress agent by supine radionuclide angiography, and the results were compared with ergometer exercise. In a preliminary group of 11 subjects (4 normal subjects and 7 patients with coronary disease), dopamine alone was administered in increments of 2.5 micrograms/kg per min to a maximum of 15 micrograms/kg per min. There were significant differences between exercise and dopamine in maximal stress heart rates, 129.3 +/- 30.0 versus 88.0 +/- 35.8 beats/min (p less than 0.05) in normal subjects and 118.9 +/- 21.1 versus 87.6 +/- 22.6 beats/min (p less than 0.05) in patients with coronary disease, as well as in maximal stress rate-pressure products, 213.3 +/- 51.4 versus 155.0 +/- 52.5 mm Hg/min X 10(2) (p less than 0.02) in normal subjects and 216.0 +/- 45.6 versus 161.0 +/- 48.6 mm Hg/min X 10(2) (p less than 0.003) in patients with coronary disease. As a result, in these patients the ejection fraction response was significantly different: -3.3 +/- 4.5% with exercise versus + 6.3 +/- 4.6% with dopamine (p less than 0.05). In a second group of 41 subjects (9 normal subjects and 32 patients with coronary disease), atropine (0.6 mg) was administered intravenously before and after every second dopamine dose increment. This produced statistically similar maximal stress heart rates as compared with exercise in all subjects, rate-pressure products in normal subjects and slightly higher values with dopamine in patients with coronary disease: 200.3 +/- 47.2 versus 183.1 +/- 43.0 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)