EPI, LV systolic pressure increased 9 + 6 mm Hg (mean increase 18%, P < .05) over the baseline value. No significant changes in LV systolic pressure at other times or in LV mid-diastolic pressures were noted. Carotid blood flow was reduced significantly for 4 min (mean reduction range, 43% to 53%). Following calcium chloride, neither LV pressures nor carotid flow were changed significantly. The results of this study show that during CPR EPI produces transient elevation of LV systolic pressure and significant reduction of carotid flow, whereas calcium chloride produces no significant effect on LV pressure or carotid flow when administered 10 min after EPI. creased cardiac index 52.4 mL/kg/min over baseline. The dopamine was stopped and the animals were allowed to return to baseline. Dopamine, 10 t~g/kg/min, was administered again after pretreatment with 0.15 mg/kg of verapamil, and increased cardiac index 47.9 mL/kg/min over the second baseline control. The resuits were not statistically different using the Student t test for paired data (P > .05). In addition verapamil pretreatment did not significantly alter dopamine's effect on the other measured and derived hemodynamic parameters evaluated in this study. It is concluded that verapamil does not affect dopamine's ability to augment cardiac output in the dosages tested.