Effect of colonic perfusion with sulfated and nonsulfated bile acids on mucosal structure and function in the rat

A single-pass perfusion system was used in conscious restrained rats to measure changes in water and electrolyte transport and in protein and deoxyribonucleic acid output after perfusing 5-15-mM solutions of sulfated or nonsulfated bile acids through the colon. Perfusion with 5 mM nonsulfated deoxycholic acid or chenodeoxycholic acid changed net water and sodium absorption to net secretion, provoked marked increases in protein and DNA output into the perfusion effluent, and caused microscopic mucosal damage. In contrast, perfusion with 5 and 15 mM sulfated deoxycholic acid or with 5 mM sulfated chenodeoxycholic acid had no effect on water and electrolyte transport and caused only modest changes in protein and DNA output. To see whether or not sulfated bile acid could prevent the effect of its nonsulfated parent compound on colonic structure and function, perfusion with a mixture of 5 mM nonsulfated and 10 mM sulfated deoxycholic acid was performed. This produced net secretion of water and sodium together with less marked increases of protein and deoxyribonucleic acid output and less pronounced microscopic mucosal damage than was seen after 5 mM nonsulfated deoxycholic acid alone. Finally, 5 mM nonsulfated cholic acid had no effect on water or sodium transport, but 5 mM sulfated cholic acid, with one alpha-hydroxyl group masked and two alpha-hydroxyl groups "exposed," reduced water transport. These results suggest that sulfation prevents the cathartic effect of alpha-dihydroxyl bile acids in the colon.