N-Butyrate rectal transport in cirrhotic patients.

Data about colonic mucosa transport of short-chain fatty acids in cirrhotic patients are still lacking. The aim of the present study was to compare the rectal mucosa transport of n-butyrate and its effect on transport of other electrolytes and endoluminal pH in normal subjects and in cirrhotic patients by using a rectal dialysis technique. Thirteen subjects with normal hepatic function tests and 17 cirrhotic patients were enrolled. Dialysis bags containing 80 mmol/liter of butyrate in a neutral pH (6.8) electrolyte solution were placed in the rectum of enrolled subjects for 60 min. Net transport rate was calculated for butyrate, sodium, chloride, potassium, and bicarbonate. The differences in pH between initial and final dialysis solutions was also evaluated in the two groups in the study. Net butyrate absorption was significantly lower in cirrhotic patients than in controls (65.2 +/- 38.6 vs 101.2 +/- 45.3 nmol/min/cm2, respectively; P = 0.02). Furthermore, cirrhotic patients showed a lower HCO3 secretion than controls (-26.9 +/- 19.9 vs -45.1 +/- 20.0, respectively; P = 0.01). No differences were found in transport of the other electrolytes. The pH in the final dialysis solution in cirrhotic patients was not significantly lower than in the controls (7.15 vs 7.35; P = 0.1). In conclusion, the impairment of butyrate absorption and the concurrent reduction of bicarbonate secretion observed in cirrhotic patients may suggest a selective hypoactivity of apical HCO3-/SCFA- antiport located at the colonocyte apical membrane.

Rectal and colonic mesalazine concentration in ulcerative colitis: oral vs. oral plus topical treatment.

AIM: To measure mucosal concentrations of mesalazine in ulcerative colitis patients treated with oral mesalazine alone, compared to patients treated with both topical and oral mesalazine. METHODS: Twenty-two patients with mild to moderate ulcerative colitis were randomized to receive 2.4 g/day of oral mesalazine (11 patients) or 2.4 g/day oral plus 4 g/day of topical mesalazine (11 patients). After 2 weeks of treatment, endoscopic biopsies specimens were taken from the rectum and in descending colon just distal of the splenic flexure and stored to -80 degrees C for later assay (HPLC). Wilcoxon's rank sum test for unpaired data was used for the statistical analysis. RESULTS: Mucosal levels of mesalazine in the rectum were significantly higher in patients who received oral plus topical treatment than in those who had oral treatment alone (52.1 ng/mg, range: 13.6-122.1 vs. 0.2 ng/mg, range: 0.2-9.7, respectively; P < 0.0001). Similarly, in the descending colon, the mucosal concentrations of mesalazine were significantly higher in patients who had oral plus topical treatment than in those receiving oral treatment alone (46.6 ng/mg, range: 6-112.6 vs. 15.9 ng/mg, range: 2.3-42.4, respectively; P=0.01). CONCLUSIONS: Topical treatment of mesalazine significantly increases mucosal concentrations of mesalazine up to the splenic flexure, supporting the rationale to treat left-sided ulcerative colitis with topical formulations of mesalazine.