Cardiac syndrome X. the possible role of Na+-Li+-countertransport activity and other pathophysiological mechanisms in pathogenesis

There are numerous pathophysiological mechanisms unequally responsible for the cardiac syndrome X development. The most important is endothelium and smooth muscle cells dysfunction that can intensify vasoconstriction and depress both endothelium-dependant and endothelium-independent vasodilatation, finally leading to coronary micro vascular dysfunction as the basis of the cardiac syndrome X pathogenesis. Together with other possible mechanisms of pathogenesis, studying the importance of increased cell membrane Na+-Li+-countertransport activity seems promising. If was found that a significant number of patients with cardiac syndrome X have increased Na+-Li+-countertransport activity, which is an in vitro marker of Na+-H+-antiporter. Therefore, it is important to measure Na+-Li+-countertransport speed in patients with coronary heart disease, because its high levels increases the chance for cardiac syndrome X, which is a coronary heart disease with no anatomic signs of coronary arteries involvement.