There are four isoforms of the α subunit (α1–4) and three isoforms of the β subunit (β1–3) of
Na, K-ATPase, with distinct tissue-specific distribution and physiological functions. α2 is
thought to play a key role in cardiac and smooth muscle contraction and be an important
target of cardiac glycosides. An α2-selective cardiac glycoside could provide important
insights into physiological and pharmacological properties of α2. The isoform selectivity of a
large number of cardiac glycosides has been assessed utilizing α1β1, α2β1, and α3β1 …