Cation Accumulation by Muscle Tissue: The Displacement of Potassium by Rubidium and Cesium in the Living Animal12

Open Access
Publisher Website
Google Scholar
Abstract
Chronic feeding of equivalent amounts of rubidium and potassium or cesium and potassium to young rats resulted in relacement of half or more of the muscle K by Rb or Cs. The final tissue-plasma concentration ratios for Rb were approximately 3 times that for K, and the ratio for Cs was more than 4.5 times the K ratio. The results suggest that muscle cells accumulate the alkaii metals in a definite order of preference: cesium > rubidium > potassium. This fact is construed as evidence against the normal accumulation of K solely by passive diffusion along an electrical gradient produced by a "sodium pump", and 2 alternative explanation are discussed which would appear to be more consistent with the present observations.