Physiological modulation of jejunal sensitivity in health and in irritable bowel syndrome.

OBJECTIVES: In irritable bowel syndrome (IBS), enhanced sensitivity to distention of the small bowel has been demonstrated. We sought to compare, in healthy subjects and in IBS patients, the effects on jejunal sensitivity and compliance of feeding, nonperceived rectal mechanoreceptor stimulation, and the above two stimuli in combination.
METHODS: Eleven female IBS patients (49 +/- 13 yr)--six with predominant constipation (IBS-C), and five with predominant diarrhea (IBS-D)--and seven healthy female controls (39 +/- 13 yr) participated. Jejunal distention was applied during fasting, 30 min after a 400-kcal meal, and also during simultaneous nonperceived rectal stimulation.
RESULTS: Jejunal sensitivity was increased after feeding in IBS patients (p = 0.004), specifically in IBS-C patients (p = 0.0001) and in controls (p = 0.02), and was reduced during rectal stimulation in IBS patients (p = 0.0001)--both in IBS-D (p = 0.0001) and in IBS-C (p = 0.03) patients--but not significantly so in controls (p = 0.06). Jejunal sensitivity remained unaltered in both IBS patients and controls during concurrent feeding and rectal stimulation.
CONCLUSIONS: Physiological stimuli in different parts of the gut modify the intensity of jejunal perception, and the interaction of such stimuli further modifies enteric sensitivity. Nonperceived rectal stimulation appears to modify the intensity of jejunal perception to a greater extent in IBS than in health.