Effects of γ-irradiation on the membrane ATPases of human erythrocytes from transfusional blood concentrates

Abstract

Irradiation of blood derivatives is employed in blood banks to avoid transfusion-associated graft-vs-host disease. As irradiation can damage membranes and membrane proteins by generation of reactive oxygen species, we investigated whether the membrane permeability, Na(+),K(+)-ATPase, and Ca(2+)-ATPase from red blood cell plasma membranes were altered by gamma-irradiation. Whole blood was collected from healthy donors and concentrated to 90% cell fraction. Within 24 h of collection, blood concentrates were irradiated with 25 Gy of gamma-radiation. At days 1, 7, 14, and 28 post-irradiation, fractions were removed and centrifuged. Na(+),K(+)-ATPase and Ca(2+)-ATPase activities from ghost membranes were assessed by gamma-(32)P-ATP hydrolysis. The Na(+),K(+)-ATPase was not immediately affected by irradiation, but it was inhibited by 40% by day 14 and until day 28. The Ca(2+)-ATPase was unaltered by irradiation. The rate and the maximal (45)Ca(2+) uptake from re-sealed inside-out vesicles were reduced, and the passive efflux of (45)Ca(2+) was increased. Thus, irradiation of blood concentrates increased the plasma membrane permeability to monovalent and divalent cations and would change ion homeostasis and cell function. We recommend the use of irradiated blood within a period shorter than 14 days after irradiation.