Effects of octreotide (1.25 micrograms/kg subcutaneously) on colonic tone and visceral perception were evaluated in 10 IBS patients, using a barostat and compared to placebo in a double-blind crossover study. Colonic sensory thresholds were also studied in healthy controls for comparison with IBS patients. Colonic tone was reflected by variations in volume of the barostat balloon. Baseline volume was 117 +/- 38 ml and was not modified by placebo (122 +/- 40 ml) or octreotide (106 +/- 42 ml). After the meal, maximal decrease in balloon volume was 75 +/- 4% following placebo (P < 0.001) beginning after 9 +/- 3 min and lasting 136 +/- 17 min. Following octreotide, the maximal decrease was 69 +/- 16% (NS vs placebo), after 10 +/- 3 min and lasting 140 +/- 22 min. In the second part, discomfort and pain thresholds were evaluated during isobaric distensions (4 mm Hg increments, 5-min duration, 5-min interval with return to pressure 0 between each). The pressure inducing discomfort was 21.2 +/- 5.9 mm Hg following placebo vs 29.6 +/- 6.6 mm Hg following octreotide (P < 0.01). The pressure inducing pain was 24.8 +/- 7.3 mm Hg following placebo vs 33.2 +/- 7.3 mm Hg following octreotide (P < 0.01). In healthy subjects, discomfort and pain were induced by colonic distensions at a mean intraballoon pressure of 32.7 +/- 5.8 mm Hg and 36.7 +/- 3.9 mm Hg, respectively. Compliance curves were not different following placebo and octreotide. Octreotide significantly increases thresholds for visceral perception in IBS patients without modifying compliance during distension nor colonic tone.