[Effect of diuretics on catecholamine stimulation of sodium reabsorption in the rat kidney]

To analyze the mechanism of the catecholamines activation of the tubular sodium transport the response of the rat's kidney to epinephrine under the action of some diuretics was investigated. Triamteren, an inhibitor of the lumenal membrane permeability to sodium, considerably weakened the stimulating effect of epinephrine on the sodium reabsorption in the renal tubules. Etacrynic acid which blocks one of the components in the system of active sodium transport in the tubular epithelium cells did not influence the activating effect of epinephrine. Strophanthin K, an inhibitor of the (Na+-K+)-activated ATP-ase completely prevented any accretion of the tubular sodium reabsorption under the effect of epinephrine. It is inferred that catecholamines can act directly on some components of the system reabsorbin sodium in renal tubules of the rat.