[Na,K-ATPase activity of erythrocytes of rats during prolonged starvation]

Activity of Na,K-ATPase (Na+,K+-adenosine triphosphatase, EC 3.6.3.9) in the whole erythrocytes was studied in dynamics of the complete rat alimentary starvation for 1, 3, 5, 7-8, and 10-12 days with water drinking ad libitum. There has been established a change of the erythrocyte Na,K-ATPase activity depending on the phase of starvation (the period connected with a certain level of metabolism). After the state on an empty stomach and adaptation to endogenous nutrition (the 0-I phase), from the 3rd to the 7-8th starvation day, the II phase, the period of compensated adaptation occurs (the euglycemia is preserved, the plateau level is preserved, the plateau level is achieved for protein loss and hormonal stimulation). Changes of the Na,K-ATPase activity level within the limits of the II phase were insignificant (p < 0.05), but loses of potassium content in plasma and erythrocytes have been from the 5th starvation day. The III phase (the 12-13th day) is the beginning of the terminal period and is characterized by a decrease of the Na,K-ATPase activity (the oubain-sensitive activity) and of Mg2+-ATPase (the oubain-independent activity), by a decrease of the plasma sodium level (prior to that, this level remained practically unchanged). Ad causes of the revealed decrease of the ATPase activities at the long-term starvation, there are considered aging of population of circulating erythrocytes (the absence of reticulocytes and young erythrocytes), depletion of cell energetic resources (hypoglycemia and glycopenia), effect of endogenous oubain, and endotoxemia.