The Na(+)/Ca(2+)-exchanger: an essential component in the mechanism governing cardiac steroid-induced slow Ca(2+) oscillations.

Plasma membrane (PM) Na(+), K(+)-ATPase, plays crucial roles in numerous physiological processes. Cardiac steroids (CS), such as ouabain and bufalin, specifically bind to the Na(+), K(+)-ATPase and affect ionic homeostasis, signal transduction, and endocytosed membrane traffic. CS-like compounds, synthesized in and released from the adrenal gland, are considered a new family of steroid hormones.

Diverse biological responses to different cardiotonic steroids.

Cardiotonic steroids (CS) such as ouabain, digoxin and bufalin, are steroidal drugs prepared from the seeds and dried leaves of the genus Digitalis, and the skin and parotid gland of amphibians, are used as a cardiac stimulant. Steroids similar or identical to the cardiotonic steroids were identified in human tissues. The available literature unequivocally supports the notion that these endogenous CS function as hormones in mammals.

Role of endosomal Na+-K+-ATPase and cardiac steroids in the regulation of endocytosis.

Plasma membrane Na(+)-K(+)-ATPase, which drives potassium into and sodium out of the cell, has important roles in numerous physiological processes. Cardiac steroids (CS), such as ouabain and bufalin, specifically interact with the pump and affect ionic homeostasis, signal transduction, and endocytosed membrane traffic. CS-like compounds are present in mammalian tissues, synthesized in the adrenal gland, and considered to be new family of steroid hormones.

Cardiac steroids induce changes in recycling of the plasma membrane in human NT2 cells.

Cardiac steroids (CSs) are specific inhibitors of Na+, K(+)-ATPase activity. Although the presence of CS-like compounds in animal tissues has been established, their physiological role is not evident. In the present study, treatment of human NT2 cells with physiological concentrations (nanomolar) of CSs caused the accumulation of large vesicles adjacent to the nucleus.