What is the mechanism of action of glycoside plants such as foxglove and oleander?

Glycoside plants like foxglove and oleander contain compounds known as cardiac glycosides, which are primarily recognized for their ability to inhibit the Na/K ATPase enzyme. The Na/K ATPase enzyme is critical for maintaining the electrochemical gradient across the cell membrane by pumping sodium out of and potassium into the cell.

When the Na/K ATPase is inhibited, sodium ions accumulate within the cell. This increase in intracellular sodium concentration subsequently affects the sodium-calcium exchanger, which relies on this gradient to function properly. As sodium builds up inside the cell, the exchange mechanism is altered, leading to an increased influx of calcium ions into the cardiac cells. The elevated calcium levels enhance myocardial contractility, contributing to the therapeutic effects of cardiac glycosides in conditions like heart failure and certain arrhythmias.

Understanding this mechanism is crucial as it highlights how glycosides can modify cardiac function and underscores their clinical importance in veterinary and human medicine.