Volume regulation byNecturus gallbladder: Basolateral KCl exit

Summary Swelling of the epithelial cells ofNecturus gallbladder caused by an 18% reduction in the osmolality of the mucosal bath is followed by rapid volume readjustment. This volume regulatory decrease requires Cl and is sensitive to the K and Cl gradients across the basolateral cell membrane. Volume regulatory decrease is not inhibited by amiloride, SITS, ouabain or bicarbonate removal. The process is blocked by bumetanide in the serosal bath. Measurement of the intracellular activities of K and Cl and the rate of volume regulation under five different experimental conditions showed that KCl exited from the cell across the basolateral membrane with a stoichiometry of 3 K to 2 Cl. This KCl exit process appears to be transiently activated following the reduction in osmolality of the mucosal perfusate.