The packed erythrocyte (RBC) lifespan of circulating biotin-labeled washed stored packed erythrocytes (SRBCs) was measured for up to 24 h. The RBC-lifespan of RBCs that were exposed to NO or the control gas are shown as in figure 3 and are superimposed. *Values of washed SRBCs differ from NO–treated SRBCs, Bonferroni-adjusted P values: 15 min: P = 0.012; 30 min: P = 0.015; 60 min: P = 0.002; 24 h: P = 0.0006. #Values of washed SRBCs differ from untreated SRBCs, Bonferroni-adjusted P values: 60 min: P = 0.073; 24 h: P = 0.02. Data are presented as mean ± standard deviation throughout. FRBC = fresh packed erythrocytes.