Abstract
Summary Na+-K+ ATPase has been found to be strongly inhibited in vitro by addition of silver, vanadium, copper, zinc, cadmium, lead and mercury. Calcium, strontium and barium enhance the dephosphorylation of ATP in the presence of Mg2+ dependent ATPase, while exerting an inhibitory effect on the monovalent cation stimulated portion. Cesium acts as an activator of Mg2+ ATPase in the system studied.