Endogenous digitalis-like Na+, K+-ATPase inhibitors, and brain function

Digitalis-like compounds are recently identified steroids synthesized by th e adrenal gland, which resemble the structure of plant cardiac glycosides. These compounds, like the plant steroids, bind to and inhibit the activity of the Na+, K+-ATPase. The possible function of the endogenous digitalis-li ke compounds has to be evaluated in view of the presence of different isofo rms of the Na+, K+-ATPase, which differ in their sensitivity to digitalis. This review focuses on recent published data on the Na+, K+-ATPase inhibito rs, the digitalis-like compounds, regarding their structure, biosynthesis a nd secretion from the adrenal gland, physiological role and pathological im plications in diseases such as hypertension and depression. Emphasis is giv en to studies describing the involvement of these compounds in brain functi on.