Role of viscosity and permeability of erythrocyte plasmatic membrane in controlling the oxygen transport effectiveness by human hemoglobin on completion of space flight
<i>Plasmatic membrane viscosity and permeability and hemoporphyrine conformation in human hemoglobin were studied on completion of long-duration space flight (LSF). Reversible increases in viscosity and selective per-meability (Na</i><sup><i>+</i></sup><i>/H</i><sup><i>+</i></sup><i>-turnover) of erythrocyte plasmatic membrane were observed immediately after and in the period of recovery from LSF. Viscosity of lipids in both externa/ and internal loca-tions of plasmatic membrane in human erythrocytes was changed after LSF. The reversible rise of the Na</i><sup><i>+</i></sup><i>/H</i><sup><i>+</i></sup><i>-turnover is likely to alter intracellular pH and oxygen binding with hemoglobin. The former is con-firmed by the concurrent reversible decline in the de-oxyhemoglobin ability to bind oxygen and the oxyhe-moglobin ability to retain oxygen. In LSF and during readaptation to the normal gravity blood levels of he-moglobin and free iron are known to be reduced and may be answerable for the hypoxic state of human organism.</i>