Physical–chemical properties of plasma membrane and function of erythrocytes of cosmonauts after long-term space flight

We studied microfluidity and selective ion permeability of plasma membranes and O2-binding properties of erythrocytes of cosmonauts during early rehabilitation after a long-term space flight (LTSF). Microfluidity of plasma membranes in surface regions was found to undergo a reversible decrease during 13–15 days following LTSF, which was accompanied by a reversible increase in relative cholesterol content. Cosmonauts’ erythrocytes revealed an increased activity of Na/H-exchanger and KCa-channel as well as a decrease in number of discocytes and increase in number of echinocytes, stomatocytes and knizocytes. Total hemoglobin content as well as oxyhemoglobin content were lowered after the LTSF, while the affinity of hemoglobin to O2 was advanced. It is suggested that the changes in Hb properties, microfluidity and selective permeability of plasma membranes following the elevated cholesterol content in the membranes can decrease tissue supply with O2.