BUTYRATE ABSORPTION AND LACTATE SECRETION IN ULCERATIVE-COLITIS

PURPOSE: Fecal electrolytes and organic anion concentrations are alter ed in ulcerative colitis, presumably reflecting changes in colon epith elial transport. Information of mucosal absorption of butyrate in acti ve ulcerative proctosigmoiditis is not available. METHODS: Dialysis ba gs containing 70 mmol/liter of butyrate in an isotonic electrolyte sol ution were placed in the rectum for 30 minutes. Net absorption or secr etion rates of butyrate, lactate, and electrolytes were determined in the rectum of 12 patients with active ulcerative colitis (UC) and in 1 0 patients with quiescent UC and then compared with 10 healthy control s. RESULTS: Net flux rates demonstrated a considerable absorption of b utyrate in patients with active inflammation of 7.5 +/- 0.4 mu mol/cm( 2)/h and quiescent colitis of 6.6 +/- 0.4 mu mol/cm(2)/h, equal to abs orption in healthy controls of 6.3 +/- 0.5 mu mol/cm(2)/h, P = 0.12. D espite normal butyrate absorption, sodium absorption was compromised i n active ulcerative colitis (11.5 +/- 1.4 mu mol/cm(2)/h) compared wit h quiescent (15.4 +/- 1.0 mu mol/cm(2)/h) and controls (18.7 +/- 0.8 m u mol/cm(2)/h) (P = 0.0006). Mucosal secretion of L-lactate was minima l in both healthy controls and quiescent UC but significantly increase d in patients with proctosigmoiditis (0.2 +/- 0.1 mu mol/cm(2)/h, 0.2 +/- 0.1 mu mol/cm(2)/h vs. 0.9 +/- 0.2 mu mol/cm(2)/h; P = 0.0001). Ap pearance of D-lactate was negligible in all three groups. CONCLUSIONS: This study demonstrates that rectal butyrate absorption is normal in UC, and it follows that butyrate supplied in enemas can be expected to be absorbed. The inflamed colonic mucosa secretes L-lactate, and the increased fecal lactate concentrations can be explained by mucosal ori gin of lactate.