Intra-luminal nicotine reduces smooth muscle tone and contractile activityin the distal large bowel

Background Nicotine may be of therapeutic value in ulcerative colitis (UC), although its mechanism of action has not been established. Objective To examine the effect of a solution of nicotine on sustained rest ing pressure (tone) and contractile activity in the human colon. Methods Ten healthy volunteers, and seven with UC in symptomatic remission took part; all were non-smokers. All 17 subjects were given nicotine or pla cebo solution on two separate occasions in a randomized sequence. A water-p erfused manometry catheter, with openings at 5, 10 and 15 cm from the tip, was placed by rigid sigmoidoscopy in the recto-sigmoid region. Baseline ton e and activity were measured for 15 min prior to instillation of 20 ml of s aline alone or with nicotine, 1.2 mg, at pH 4.5. Observations were made ove r the subsequent 15-20 min. Results Baseline spontaneous activity in all subjects showed both high- and low-frequency components; in three patients with UC, the low-frequency act ivity was of high amplitude, The nicotine reduced both tone and activity in all subjects, with reduction or abolition of the large contractions in UC, Tone in all 17 subjects was reduced significantly at 3 min after nicotine (P = 0.000015, sign test); the rate of recovery varied in individuals, Resu lts from normals and UC did not differ significantly from each other, No si gnificant change in tone or activity was observed with the saline solution. Conclusion Intra-luminal nicotine significantly reduces both smooth muscle tone and contractile activity in the recto-sigmoid colon in both normal sub jects and patients with UC. Eur J Gastroenterol Hepatol 11:1299-1304 (C) 19 99 Lippincott Williams & Wilkins.