Figure 1.

Effect of oxygen tension and extracellular Ca²⁺ on phosphatidylserine (PS) exposure in red blood cells (RBCs) from sickle cell patients. RBCs were incubated for 18 hours at four extracellular [Ca²⁺]'s (0.5, 1.1, 2.0 and 5.0 mM) after which they were labelled with FITC-annexin (as described in Section 2). Histograms representing mean percentage of positive RBCs ± S.E.M. for 5 different patients. *P < .01 deoxy compare to oxy; ⁺ P < .05 cf 0.5 mM Ca²⁺ deoxy; ^# P < .01 cf 0.5 mM Ca²⁺ deoxy.