Study of ion transport across biopsies of ileostomy in vitro: search for evidence of intestinal 'adaptation' after colectomy.

To explore the possibility that small intestinal 'adaptation' may occur after colectomy we examined the ability of ileal mucosal biopsies, taken from patients with ileostomies, to transport electrolytes in vitro. Ileostomy mucosal electrical potential difference was higher (5.4+/-0.5 mV) than in normal mucosa (3.3+/-0.3, P less than 0.001), resistance was higher (98+/-12, against 40.3+/-2.8 omega cm-2), while short circuit current was lower (54.8+/-6.0; against 89.9+/-6.1 muA.cm-2). Net sodium absorption, 1.25+/-0.41 mumol.cm-2.h-1 (n=6), rose on addition of glucose (15 mM.1-1) to 11.57+/-0.8 mumol.cm-2.h-1 (n=4), and these were similar to results from normal ileum. Net chloride transport was also similar to noraml. In one subject, with intermittent ileostomy diarrhoea, net sodium absorption was normal, 2.14 mumol.cm-2.h-1, but there was marked active chloride secretion, 14.03 mumol.cm-2.h-1. These studies do not provide any evidence of enhanced electrolyte absorption across ileal mucosa as a response to colectomy. Some cases of ileostomy diarrhoea may be due to active chloride secretion.