Ionic dependence and vanadate sensitivity of (Na +, K +)-ATPase isolated from branchial sac of ascidians

Abstract

1. 1. Ion dependence and vanadium-induced inhibition on branchial sac ATPase in five species of ascidian Phlebobranchiata (vanadium-accumulating) and Stolidobranchiata (iron-accumulating) were studied. 2. 2. The ATPase was obtained from the microsomal fraction, which was prepared from each ascidian branchial sac. 3. 3. The ATPase was dependent on Mg 2+ and activated by exogenous Na + + K +. 4. 4. Ouabain inhibited the ATPase activity in vitro, 10 μM to 100 μM vanadate, in vitro, suppressed the (Na +, K +)-ATPase.