Potassium Secretion in Response to Taurodeoxycholic Acid in the Newborn Rabbit Colon

The newborn colon fails to secrete Cl in response to concentrations of dihydroxy bile acid that cause Cl secretion in adult colonic tissue in vitro. Bile acids also cause secretion of potassium in adult tissues, but there is no information concerning bile acid effects on potassium transport in newborn colon. We mounted newborn rabbit distal colon in Using chambers specially designed for newborn colon and measured potassium transport. Basal potassium transport was secretory. Taurodeoxycholic acid, 100 μM. (TDC) decreased Jknet from −0.76±0.07 to −0.94±0.11 μEq cmh, p < 0.05, without increasing Isc. Serosal ouabain, 0.1 mM, abolished the secretory response to TDC. Mucosal Ba, a potassium channel blocker in many epithelia, did not inhibit K secretion. Similar serosal exposure to TDC in adult colon tissues decreased Jnet, from −0.09 ± 0.29 to - 1.63 μEq cm h, p < 0.01, and increased Isc. We conclude that, although the chloride secretory response to dihydroxy bile acids is absent in the newborn, K secretion is elicited in the newborn, similar to the adult colon.