The effect of exogenous adenosine triphosphate on potassium movements in HeLa cells

The effect of exogenous adenosine triphosphate (ATP) on the potassium movements of cultured HeLa cells has been studied. The results obtained were consistent with the hypothesis that, in these cells, externally applied ATP activates a tightly coupled potassium-potassium (K-K) exchange mechanism. The response to ATP was characterized by a transient, 20-fold increase in both the potassium influx and potassium efflux. The tight coupling of the K-K exchange mechanism was confirmed by the results of several different types of experiment, all of which demonstrated the consistent matching of the ATP-stimulated fluxes. Two different strains of HeLa cells gave quantitatively different responses under similar experimental conditions. The reason for this difference was investigated and evidence was obtained which was consistent with the view that the membrane potential also influenced the HeLa cell K-K exchange mechanism.