Effect of aging on oxygen permeability of wild type (WT) and AQP1‐RhAG double knockout (dKO) mouse red blood cells

Abstract

The dogma that all gases move through red blood cell (RBC) membranes by dissolving in and diffusing through the membrane lipid is no longer correct. Our preliminary data on mouse RBCs genetically deficient in both aquaporin‐1 (AQP1) and Rh complex (mainly RhAG) suggest that these two proteins account for ~60% of membrane O2 permeability. Using stopped‐flow (SF) analysis of hemoglobin (Hb) absorbance spectra, we now examine the effect of aging on the rate constant of Hb deoxygenation (kHbO2) of RBCs from WT mice and mice genetically deficient in both AQP1 and RhAG (double knockout, dKO). Studying mice at five ages (2~3 months, 6 months, 12 months, 18 months, and 24 months), we find that RBCs from WT mice at ages from 2~3 months through 12 months all have similar kHbO2 values (N = 6 mice/group). RBCs from WT mice at 18 (N = 6) and 24 months (N = 2) have mean kHbO2 values that—compared to RBCs from WT mice 2~3 months old—decrease by 8% at 18 months and by 10% at 24 months. These decreases in mean kHbO2 do not yet reach statistical significance, using a Holm‐Bonferroni correction. Regarding RBCs from dKO mice, we observe similar kHbO2 values for all ages from 2~3 months to 18 months (N=5 for 18 months), inclusive. RBCs from dKO mice at 24 months are currently under investigation. We plan to extend this study to RBCs from mice genetically deficient in just AQP1 or RhAG. If the trends continue (i.e., for RBCs from aging WT but not dKO to exhibit a fall in kHbO2), it would be consistent with the hypothesis that the non‐AQP1/RhAG component of RBC membrane O2 permeability is independent of aging, whereas the AQP1 and/or RhAG component declines with aging.Support or Funding InformationSupported by ONR N00014‐15‐1‐2060, ONR N00014‐16‐1‐2535 to WFBThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.