Epithelial ion transport in the ileal J-pouch after proctocolectomy in the rat.

Abstract

In ulcerative colitis and polyposis coli, creation of an ileal pouch with ileoanal anastomosis after proctocolectomy has become a common surgical method. The aim of our study was to characterize the adaptation of the epithelial ion transport function in the pouch by using electrophysiologic techniques. Proctocolectomy and ileoanal anastomosis was performed in rats either with (pouch) or without (control) creation of an ileal J-pouch. To characterize the epithelial barrier function, impedance analysis was performed 6 months after surgery. Epithelial resistance was 29 +/- 2 omega.cm2 in controls and was unchanged in the pouch (28 +/- 4 omega.cm2; NS). In contrast, subepithelial resistance increased from 33 +/- 3 omega.cm2 to 54 +/- 5 omega.cm2 (P < 0.01) owing to work hypertrophy of the muscle layers in the pouch. To detect changes in net ion transport, ion tracer fluxes were measured in the Ussing chamber. In control ileum, absorptive net Na and Cl fluxes of similar magnitude were present, indicating that electroneutral NaCl absorption was the predominant ion transport system. Neither Isc nor net Na and Cl fluxes were significantly altered in the pouch. Glucose-coupled Na absorption was measured as the 3-o-methyl-glucose-induced increase in Isc. Km remained unaltered, while Vmax decreased from 7.5 +/- 2.1 mu eq.h-1 cm-2 in controls to 1.7 +/- 0.8 mu eq.h-1 cm-2 (P < 0.05) in the pouch. Then, maximal transport capacity for electrogenic Cl secretion was measured as the Cl-induced increase in Isc blockable by serosal bumetanide (in the presence of theophylline and prostaglandin E1).(ABSTRACT TRUNCATED AT 250 WORDS)