The Properties of Red Blood Cells from Patients Heterozygous for HbS and HbC (HbSC Genotype)

Figure 3

Components of K⁺ transport pathways and sickling in red blood cells (RBCs) from sickle cell disease patients heterozygous for HbS and HbC (HbSC genotype). K⁺ influxes are given as flux units [mmol⋅(l cells⋅h)^-1] measured at 5 mM [K⁺]_o and numbers of sickled cells as a percentage of total RBCs in fully oxygenated (150 mmHg O₂) or deoxygenated (0 mmHg) conditions. Although this technique measures a K⁺ influx, because of the high K⁺ content of RBCs, net solute movement through the transport systems will be outwards. KCl cotransport activity was calculated as the Cl^--dependent K⁺ influx, Gardos channel activity as the clotrimazole (5 𝜇M)-sensitive K⁺ influx, and 𝑃_sickle as the Cl^--independent K⁺ influx (Cl^- substituted with NO₃₋). Sickling, 𝑃_sickle, and Gardos channel activation occurs in deoxygenated conditions—as for HbSS RBCs—but KCC activity is low when O₂ is removed (as in RBCs from HbAA cells). Data taken from [64].