We studied plasma catecholamine levels in 10 patients with frequent spontaneous episodes of coronary artery spasm to evaluate the role of the sympathetic nervous system. Peripheral venous norepinephrine in supine and upright postures, urinary excretion of catecholamines, and functional testing of the sympathetic nervous system did not differ from the same measurements in control subjects. Arterial and coronary sinus levels of norepinephrine and epinephrine drawn early in ischemia were not elevated over baseline; coronary sinus norepinephrine levels were higher than those in arterial samples and rose from 315 +/- 32 (pg/ml +/- SE) at the onset of ST elevation to 490 +/- 49 pg/ml late in ischemia (p less than 0.05). Plasma epinephrine levels, higher in arterial than coronary sinus samples, also rose significantly only late in ischemia, from 44 +/- 14 pg/ml to 148 +/- 35 pg/ml (p less than 0.05) in arterial blood and from 33 +/- 10 pg/ml to 108 +/- 29 pg/ml in coronary sinus samples (p less than 0.05). Generalized sympathetic nervous system activation is not likely to be the sole cause of coronary artery spasm.