Hemodynamic effects of intravenous and oral pindolol and atenolol were assessed in ten healthy volunteers by left ventricular echocardiography and systolic time intervals. Measurements were made at rest and during hand-grip-induced isometric exercise. Drug doses were pindolol 0.015 mg/kg intravenously and 10 mg/day orally, atenolol 0.1 mg/kg intravenously, and 50 mg/day orally. Heart rate at rest was reduced by both drugs. The reduction caused by atenolol during oral treatment was significantly greater (p less than 0.01). Intravenously only pindolol reduced mean arterial pressure. During oral treatment atenolol reduced the mean arterial pressure nonsignificantly. Both drugs lowered heart rate during isometric exercise, atenolol being significantly more effective. During oral treatment atenolol blunted the heart-rate reaction to exercise. Mean arterial pressure during isometric exercise rose slightly with both drugs after intravenous administration. During oral treatment only atenolol reduced the mean arterial pressure significantly. Intravenous atenolol reduced cardiac contractility at rest, indicated by significant decreases in fractional shortening, ejection fraction, and the mean velocity of circumferential fiber shortening. In contrast, intravenous pindolol and oral therapy with either drug did not change contractility. Intravenous atenolol raised total peripheral resistance. The preejection period/left ventricular ejection time ratio decreased with intravenous pindolol, while atenolol increased it. In conclusion, atenolol had more negative inotropic and chronotropic effects, especially after acute intravenous administration. Only atenolol reduced cardiac output and increased peripheral resistance. After repeated oral administration, these effects were less apparent.(ABSTRACT TRUNCATED AT 250 WORDS)