Role of the Na+K+-ATPase in the cardiotonic action of cardiac glycosides.

In terms of evolution, the Na+,K+-ATPase is one of the oldest proteins. It is intriguing that this membrane-based enzyme has become biologically consistent with a multifunctional protein. One of the most interesting aspects of the Na+,K+-ATPase is that it contains a specific receptor domain for the oldest plant origin cardiotonic drug and that it is involved in the regulation of myocardial contractility.