The response of coronary hemodynamics to the intracoronary (i.c.) bolus administration of gallopamil, 1.5 and 3.0 micrograms/kg, was evaluated in 14 patients with normal coronary arteries. Gallopamil, 3.0 micrograms/kg, induced a small and transient decrease in systolic and mean arterial pressure and a small increase in the preejection period. Coronary sinus blood flow increased significantly at 30 s (p less than 0.01) and returned to baseline 10 min after gallopamil administration. Coronary vascular resistance was still reduced at 10 min and returned to baseline at 15 min. Myocardial O2 consumption and extraction decreased significantly (p less than 0.01) at 30 s. While myocardial O2 consumption returned to baseline 15 min after gallopamil administration, myocardial O2 extraction was still significantly reduced at this time. Milder and more transient changes were observed after i.c. administration of the lower dose (1.5 micrograms/kg), and no significant changes were found after i.c. administration of saline. These data show that i.c. gallopamil, in patients with normal coronary arteries, induces direct, transient, and dose-related peripheral coronary vasodilation. The reduction of myocardial O2 consumption and extraction suggests a direct negative inotropic and metabolic effect of gallopamil.