RECTAL TONE, DISTENSIBILITY, AND PERCEPTION - REPRODUCIBILITY AND RESPONSE TO DIFFERENT DISTENSIONS

Increasing interest; is focusing on the role of intestinal tone, diste nsibility, and mechanosensation in the genesis of abdominal symptoms. Experimental approaches usually feature balloon distension of the bowe l with measurements of perception, tone, and compliance and/or elastan ce; however, the methodologies are standardized incompletely. We exami ned the reproducibility of repeated assessments of sensory perception, basal tone, and compliance and/or elastance of the rectum during dist ension. We also evaluated the response to inflations that varied in re gard to control of pressure or volume, pattern of distension, and rate of inflation. Five healthy volunteers were studied under two separate protocols. The first featured a series of experiments on each of 5 da ys; the other consisted of 2 separate days of study. Repeated distensi ons evoked reproducible responses of sensation and compliance and/or e lastance on a single day, providing a conditioning distension preceded them. Day-to-day variability was also sufficiently small to allow val id comparisons to be made on different days in healthy persons. The co nfiguration of the distension profile (phasic, staircase, or ramp) and the rate of inflation (from 1 to 40 ml/s) had little effect on disten sibility or perception. Perceptions were sometimes transient and somet imes constant, but no relationship was found between these temporal fe atures and the magnitude of the stimulus. These observations help prov ide a basis as to how the responses to rectal distension can be best s tudied.