Regulation Of Na, K-ATPase By Angiotensin Ⅱ In Guinea-Pig Ventricular Myocytes

Na,K-ATPase is a membrane-bound protein that presents in the cell membrane of nearly all eukaryotic cells which consists ofα,βandγsubunits. The transmemraneαsubunit is responsible for the catalytic and transport properties of the enzyme, and four isoforms (α1,α2,α3,α4)of it have been found out until now. Na,K-ATPase widely distributes in myocardial cells, and is critical in maintaining the resting membrane potential and the excitable properties of heart. Many studies about the relationship of angiotensin II (AngII)and the Na,K-ATPase activity, isoforms and signal conduction pathway in vascular smooth muscle cells, thyroid cells, and breast cancer cells have been made. Douglas et al. discovered that in rat proximal tubule, AngII rapidly stimulated the activity of Na-K-ATPase in 2 min or less by a mechanism which could involve in the changes in phosphorylation and conformation of Na-K-ATPase. Marsigliante et al. reported that in rat thyroid cells, Ang II up modulated Na,K-ATPase activity in PC-Cl3 cells through the AT1 receptor via activation of atypical PKC-z after 10 minutes incubattion. But there were still some papers reported that AngII inhibited Na,K-ATPase activity and that isolated enterocytes stimulated with increasing AngII...