The electrical potential difference across human ileostomy mucosa.

Some of the characteristics of the electrical potential across human ileostomy mucosa were assessed by measuring potential difference (P.D.) between ileostomy lumen and forearm skin in 28 subjects, 19 of whom had had ulcerative colitis and 9 Crohn's disease. The mean P.D. at 3 to 5 cm from the tip of the ileostomy was 17.2 mv +/- 0.6 (SEM) in the ulcerative colitis group and 16.5 mv +/- 1.1 in the Crohn's disease group. The P.D. was highest at the tips of ileostomies and decreased to about half the tip level at 10 to 15 cm deep to the tip. Even at this distance from the tip, P.D. was apparently higher than values reported in normal ileum. P.D. rose during the first few weeks after colectomy and reached a stable value at about 2 months. Plasma aldosterone levels were normal in 6 subjects but despite this, administration of an aldosterone antagonist, spironolactone, caused a fall in P.D. These apparently conflicting observations suggest that the raised P.D. was maintained, at least in part, as a response to normal levels of aldosterone and an increased sensitivity to aldosterone by ileal mucosa near to an ileostomy is postulated. A significant correlation between P.D. and salivary Na:K ratios also supports a relationship between P.D. and aldosterone levels. Another patient, with a jejunostomy, also had a high transmucosal P.D., suggesting that jejunal mucosa may respond in a similar manner. No evidence in favor of active K secretion was discovered, because K concentrations in ileostomy ejecta were no greater than those which could be predicted as a passive response to the P.D. except in some subjects during the 1st week after surgery.