Saturation behavior of ascites tumor cell chloride exchange in the presence of gluconate

Steady state Cl- flux across the Ehrlich mouse ascites cell membrane was studied when gluconate replaced Cl- in the external medium. Saturation behavior was observed; K 1/2 was 23.9 mM Cl- and V was 758 micromol.g-1 dry weight.h-1. The cells lost K+, Cl- and H2O, consistent with relative impermeability to gluconate, and the Cl- efflux rate coefficient was elevated. The results indicate that a major portion of Cl- exchange occurs as a membrane transport process and suggest that the process is sensitive to intracellular Cl- levels.