Effect of sodium bicarbonate and deoxycholic acid on the gastric mucosa of the rabbit.

Deoxycholic acid (DC), a secondary bile acid and one of those most toxic to the gastric mucosa, is precipitated and becomes inactive in the acidic lumen of the rabbit stomach. We sought to determine whether or not oral administration of sodium bicarbonate (NaHCO3) and DC injure the rabbit gastric mucosa. Rabbits were divided into six groups. Group 1 was given 10 ml of 10% NaHCO3 followed by 50 ml of 20 mM DC orally every day. These animals had diarrhea and three of five died on the fourth or fifth day. Therefore, the two remaining animals were killed on the fourth day. Animals in group 2 were given 10 ml of water followed by 50 ml of 20 mM DC, those in group 3 were given 10 ml of 10% NaHCO3 followed by 10 mM DC, those in group 4 were given 10 ml of water followed by 50 ml of 10 mM DC, and those in group 5 were given 10 ml of 10% NaHCO3 followed by 50 ml of the DC solution. Group 6 was not treated. Although all animals in the group 2 and one of three in group 3 had diarrhea, they were alive and were killed after eight or nine days. Gross and histological examinations showed that the degrees of gastric mucosal damage in groups 1 and 2 were more severe than in groups 3 and 4. Mucosal damage in group 3 was more severe than in group 4. The gastric mucosa in group 5 was similar to that in untreated animals (group 6). These data suggest that when the gastric lumen is alkalinized by NaHCO3, DC causes more severe damage to the mucosa than it does when the lumen is acidic.