The effects of nifedipine (20 mg orally) on esophageal body resting tone and perception of esophageal distension were compared with those of placebo in 10 healthy volunteers, using a double-blind crossover design. A 3-cm silicon balloon positioned 10 cm above the lower esophageal sphincter was inflated with 2-20 ml of air, in 2-ml increments. The subjects scored their chest sensations, while pressure in the balloon was continuously recorded. In each experiment three series of measurements were made, at baseline and 15 and 30 min after administration of nifedipine or placebo. Bench tests were run to determine pressure-to-volume relationships for each of the balloons used in the study. Thirty minutes after nifedipine ingestion, a significant decrease in systolic blood pressure (from 112.6 +/- 2.3 to 99.0 +/- 2.0 mm Hg) was observed. Amplitude and duration of esophageal peristaltic contractions were significantly decreased by nifedipine (from 128.1 +/- 16.7 to 98.7 +/- 10.6 mm Hg and from 3.9 +/- 0.3 to 3.3 +/- 0.2 sec, respectively). With balloon volumes of 8 ml and higher, balloon pressures were higher with the balloon in the esophagus than on the bench, the difference being determined by the compliance of the esophagus. This difference rose from 18.5 +/- 6.8 to 40.2 +/- 7.2 mm Hg (8-20 ml) with placebo and from 23.1 +/- 3.7 to 35.9 +/- 5.8 mm Hg with nifedipine. No significant differences between nifedipine and placebo were found. The esophageal sensation scores increased linearly with increasing balloon volume from 6 ml onwards. Nifedipine had no significant effect on the perception of esophageal balloon distension.