Absence of effect of nicotine on rectal sensation, rectal compliance, and anal sphincter pressures in healthy subjects.

We examined the effect of nicotine on rectal sensation, rectal compliance, and anorectal sphincter function in healthy volunteers. Eleven healthy (ex-smoker) subjects were randomized in a double-blind, crossover, placebo-controlled study of 12 mg nicotine-containing chewing gum. All treatment periods (nicotine or placebo chewing gum) were preceded by a control period without chewing gum. Crossover study was done after a washout period of more than seven days. The following measurements were made: highest anorectal sphincter tone, highest anorectal sphincter squeeze tone, percentage relaxation of the anorectal sphincter with rectal balloon distension, threshold of rectal sensation, maximal tolerable volume of air inflation of a rectal balloon, and rectal compliance. There was no significant difference in the two control periods. Chewing placebo gum had no significant effect on any of the measurements when compared with control. Compared with placebo, nicotine did not significantly affect on any of the measurements. We conclude that neither nicotine nor the sham-feeding effect of chewing placebo gum appear to have any effect on anorectal sensorimotor function or on rectal compliance in healthy ex-smokers.