Could Na,K-ATPase play a role in potassium leakage from irradiated erythrocytes?

Background: In developing countries, the access to red blood cell (RBC) irradiators is restricted. Thus, it is a common practice in blood banks to stock irradiated RBC units until they expire. The aim of this work is to elucidate the involvement of Na,K-ATPase in potassium leakage from prophylactically irradiated RBCs.

Methods: Whole blood was collected from healthy donors, and blood concentrates were irradiated with 25Gy of γ-radiation within 24h of collection. At days 3, 5, 7, 9, 11, 14 and 28 post-irradiation, fractions were removed and centrifuged and Na,K-ATPase activity from ghost membranes was determined.

Results: The inhibition of Na,K-ATPase activity in RBCs reached 12.6% by day 7 of storage and up to 50% by day 14 of storage. The addition of vitamin C prevented the irradiation-induced loss of Na,K-ATPase activity. The irradiation of RBCs provoked an increase in potassium plasma levels and a decrease in sodium plasma levels. The incubation of RBCs with ouabain did not change the sodium or potassium levels in the plasma, and the addition of vitamin C only partially prevented a decrease in sodium levels caused by irradiation.

Conclusion: Because the inhibition of Na,K-ATPase by ouabain did not cause potassium accumulation in the plasma, we conclude that the irradiation-induced inhibition of the pump is not a key factor driving this effect.