Abnormal effect of sera from patients with atherosclerosis on calcium influx into normal erythrocytes

The rheology of red blood cells in patients with atherosclerosis is abnormal. To investigate this further, the authors examined the effect of sera from patients with atherosclerosis on the handling of calcium by the erythrocyte membrane. Normal erythrocytes were filled with a photoprotein (aequorin) which emits light on contact with calcium. These photoprotein-loaded normal erythrocytes were then incubated overnight with the serum from normal subjects (n = 34) and from patients with atherosclerosis (n = 30). There was a significant decrease in basal calcium leakage, as measured by the amount of light produced following the addition of triton X-100. Induced calcium influx, as measured by the amount of light produced following the addition of ionophore A23817, was significantly greater in the photoprotein-loaded erythrocytes incubated overnight with the serum from patients with atherosclerosis compared with those incubated with the serum from normal subjects (p < 0.01). This modulation of Ca2+ handling in erythrocytes by a serum factor from patients with atherosclerosis could account for the alterations in erythrocyte function, such as red cell deformability, observed in atherosclerosis.