The influence of isosorbide dinitrate (ISDN) and food ingestion on superior mesenteric artery impedance was investigated in 24 healthy volunteers (age 40 +/- 2.7 years). Superior mesenteric artery circulation was assessed by duplex ultrasound. Pulsatility index (PI) was considered as a parameter of vascular resistance and was calculated as the peak-to-peak amplitude of the waveform divided by the mean amplitude. The subjects were randomly allocated to four groups (ISDN, meal, ISDN + meal, meal + ISDN). PI measurements were performed in resting and fasting conditions and serially for 1 h after sublingual 5 mg ISDN, ingestion of a 300-kcal, 300-ml mixed liquid meal; sublingual 5 mg ISDN followed 10 min later by the test meal; and ingestion of the test meal followed 5 min later by sublingual 5 mg ISDN. Five minutes after 5 mg sublingual ISDN, PI had increased from 6.8 to 12.4, while after intake of a meal PI had decreased from 7.6 to 4.9. Separate effects of 5 mg ISDN and meal intake lasted for at least 1 h. The reflex vasoconstrictive effect of 5 mg ISDN on the superior mesenteric artery circulation was counterbalanced by ingestion of a meal in healthy volunteers.