Effect of strophanthidin on fluxes of potassium in rabbit kidney slices

¹ Laboratory of Kidney and Electrolyte Metabolism, National Heart Institute, National Institutes of Health, Bethesda, Maryland

The effect of the cardiotonic steroid strophanthidin on the K content and K⁴² exchange rates of rabbit kidney slices has been determined. Strophanthidin has been shown to decrease the influx of K into renal tubule cells, thereby accounting for an observed reduction in the K content of slices in vitro and a diminished rate of secretion of K in vivo. It is probable that the inhibitor also decreases the rate constant for efflux of K from the tubule cells. However, the latter conclusion requires qualification since the thickness and structure of kidney slices complicate the interpretation of isotope exchange data, particularly in this case with respect to the analysis of changes in K efflux.