Sodium fluxes in the Ehrlich mouse ascites tumor cell

Abstract

Na⁺ transport was measured in the Ehrlich mouse ascites tumor cell by isotopic and chemical methods. Evidence for an initial, rapidly exchanging Na⁺ compartment was found in addition to a slower compartment. Net Na⁺ efflux might constitute less than half the total efflux. Influx of Na⁺ decreased while intracellular Na⁺ was falling, demonstrating a dependence of Na⁺ influx on intracellular Na⁺ content. Taken together, the data provide evidence for a component of Na⁺ transport which is mediated but not active.