Effect of Bile Salts on Carbonic Anhydrase from Rat and Human Gastric Mucosa

Gastric carbonic anhydrase (CA) is believed to play an important role related to cytoprotection, and duodenogastric reflux of bile salts (BS) is suspected of having a causal role in many pathologic conditions. Thus, we decided to investigate the effect of free and conjugated BS on human and rat gastric CA activity. Cholate exerted the most potent inhibitory activity on both human (I50 = 2.24 mM) and rat (I50 = 1.68 mM) gastric CA, followed by glycochenodeoxycholate and taurocholate (I50 = 6.90 mM and 13.67 mM on rat gastric CA). Human and rat whole bile produced 10-90% and 20-40% inhibition of gastric CA of the same species. Since the concentrations of free and conjugated BS tested in this study can be found in the postgastrectomized stomach, our data suggest that inhibition of gastric CA might be one mechanism contributing to the gastric mucosa damage caused by BS refluxing into the stomach after gastric surgery.