Dimensions of cells and lateral intercellular spaces in living Necturus gallbladder.

The size and shape of the cells and lateral intercellular spaces were measured in living Necturus gallbladder epithelium. Interspace volume was determined as a function of the transepithelial hydrostatic pressure difference. The compliance of the lateral membranes of the gallbladder cells was calculated from the interspace pressure-volume curves in both the presence and absence of fluid transport. Cell and interspace volume were studied when the NaCl in the mucosal bath was substituted by equiosmolar quantities of sucrose. The cells decreased in volume after the removal of mucosal NaCl and increased to control volume when the mucosal perfusate was 100 NaCl Ringer. The interspaces collapsed when fluid transport was inhibited by the removal of mucosal NaCl and reopened when NaCl was reintroduced to the mucosal bath. The rate of change of cell volume was used to calculate the active transport rate and the flux of NaCl across the apical membrane. The magnitude of the cell volume change during NaCl replacement indicated that all intracellular NaCl was readily accessible to be transported out of the cell.