The Effects of Cations on the Inhibition of Sodium and Potassium Activated Adenosinetriphosphatase by Beryllium

Abstract

1. When Na-K ATPase [EC 3. 6. 1. 3] preparation from guinea pig kidney cortex was preincubated with BeCl₂ in the presence of Mg⁺⁺, the activity was inhibited.
2. For beryllium inhibition of Na-K ATPase, Mg⁺⁺ was necessary and was substituted by Mn⁺⁺, but not by Ca⁺⁺
3. Beryllium chloride concentration required for 50% of Na-K ATPase activity was 1.8×10^-6M.
4. In the presence of Mg⁺⁺, K⁺ increased the rate of inhibition and was substituted by NH₄⁺ or Rb⁺, but not by Li⁺.
5. Sodium ion not only protected the enzyme from the inhibition in the presence of K⁺ and Mg⁺⁺, but also reversed the inhibition.
6. Protective effect of Na⁺ was remarkable in the absence of K⁺ or presence of its low concentration.
7. Ouabain did not affect the rate of inhibition in the presence of K⁺ and Mg⁺⁺.