MOVEMENT OF THALLOUS ION ACROSS THE ASCITES CELL-MEMBRANE

The movement of Tl+ across the [mouse] ascites cell membrane was characterized. Analogous to previous findings for 86Rb+ (used as a tracer for K+), 204Tl+-influx was resolved into 3 components: a ouabain-inhibitable pump flux, a passive flux and a furosemide- or .**GRAPHIC**. -sensitive exchange flux. Tl+ moved approximately 9 times faster across the membrane than K+; the pump/leak ratio was equal for the 2 ions. The pump- and leak-pathways apparently share a common rate-limiting step. The exchange mechanism provides close coupling between the Tl+- and K+-gradients.