We evaluated the effects of nitrendipine, a calcium antagonist of the dihydropyridine group, on cerebral blood flow (CBF) in nine patients with mild to moderate hypertension. The CBF was determined under placebo, 2 h after the first dose (short term) and after 4 weeks (long term) of regular nitrendipine treatment. The CBF was determined using the xenon-133 method. All patients were on placebo for 2-4 weeks before nitrendipine administration. The mean age was 48 years (range of 35-67 years). Blood pressure fell from 169 +/- 19/110 +/- 16 to 147 +/- 12/94 +/- 11 mm Hg after the first dose and to 140 +/- 12/92 +/- 9 mm Hg after long-term administration (p less than 0.01). The corresponding CBF did not change significantly from 37.5 +/- 4.8 ml/100 g/min before to 38.7 +/- 4.5 ml/100 g/min 2 h after the first dose and 38.1 +/- 6.0 ml/100 g/min after long-term administration of nitrendipine (p = 0.3 and p = 0.8, respectively). In conclusion, nitrendipine did not alter the CBF of mildly to moderately hypertensive patients. Particularly, the CBF was maintained during short-term and long-term administration despite significant blood pressure reduction.