Duplex ultrasound scanning has been used to assess mesenteric blood flow in normal and disease states. To investigate this technique we studied nine normal volunteers at rest and under conditions known to modify intestinal blood flow. After a baseline mesenteric duplex scan, each subject was given one of three treatments in random order: (1) test meal (710 kcal), (2) intravenous glucagon (40 micrograms/min), or (3) intravenous vasopressin (0.2 units/min). Peak systolic and diastolic velocities and vessel diameters were measured at intervals after treatment in the celiac and the superior mesenteric arteries (SMAs) and the right common carotid artery. Resting velocities did not differ among the groups. Peak systolic velocity increased significantly in both celiac and SMAs after the meal, with maximal changes in the celiac artery preceding those in the SMA in most subjects. Early diastolic flow reversal in the SMA was consistently lost after the meal (eight of nine subjects). Velocity changes after glucagon closely paralleled those after the meal. Vasopressin produced significant decreases in peak systolic velocity in both visceral vessels. No changes in vessel diameter were noted after any treatment. Coefficient of variation for repeated measures of peak velocities was 19% in the celiac and 12% to 16% in the SMA and the common carotid. The coefficient of variation for repeated measurements of arterial diameter was 6% to 8% in the SMA and 11% in the celiac artery. Clinically relevant changes in mesenteric hemodynamics can be reproducibly detected and quantitated by means of current duplex ultrasound technology. The similarities between the visceral arterial responses to a meal and glucagon are of interest.(ABSTRACT TRUNCATED AT 250 WORDS)