Evidence for a K+-stimulated Na+ efflux at the plasmalemma of barley root cells

Summary The influence of K⁺ on the Na⁺ fluxes of barley root cells was investigated. A increased K⁺ concentration (K⁺ influx) results in a transient increase of the plasmalemma efflux of Na⁺ followed by a decrease, and in a decrease of the cytoplasmic content and the tonoplast influx of Na⁺. These results are consistent with a Na-K-pump at the plasmalemma.