Abstract: Objective To evaluate the effects of different L-arginine concentration on the oxygen affinity P₅₀ of red blood cells and frozen red blood cells in different storage periods. Method sL-arginine solution was added into the CPDA or MAP preservation solution after thawing of frozen red blood cells,before preservation of frozen red blood cells and red blood cells,to make the final concentration of L-arginine 5 mmol/L,10 mmol/L and 50 mmol/L. The changes of erythrocyte oxygen affinity P₅₀ were detected at 0d,7 d,14 d,21 d,28 d and 35 d during the storage periods,respectively. Results With the extension of the preservation periods,the overall decrease of erythrocyte oxygen affinity was observed in L-arginine solution was added into the CPDA or MAP preservation solution after thawing of frozen red blood cells,before preservation of frozen red blood cells and red blood cells. Especially during the first two weeks of the preservation periods,the decrease was significant.Decreased by 15.6% over 14 d,then it fell more slowly,and day 35 was down 25.4%.At the end of the inventory period,the value is only 74.6% of the date of blood collection; The overall decrease of erythrocyte oxygen affinity was observed in frozen red blood cells.The effect of L-arginine on oxygen affinity P₅₀ of frozen red blood cells was greater than that of suspended red blood cell,and the effect of L-arginine addition was most significant after thawing of frozen red blood cells; L-arginine with a final concentration of 10mmol/L had the most significant effect on the improvement of erythrocyte oxygen affinity P₅₀ in the three groups,and the difference was statistically significant. Conclusion L-arginine at a suitable concentration can improve the oxygen affinity P₅₀ of red blood cells and frozen red blood cells.

Key words: L-arginine, Red blood cell, Oxygen affinity