Effect of sphering on erythrocyte deformability

Abstract

The deformability of sphered erythrocytes produced in vitro by fragmentation loss of membrane in a glass micropipette or by heating at 48°C has been compared to spheres in metabolically depleted blood and in spheres from blood bank blood by measuring the pressure for passage through a 2.8-μ micropipette. Progressive membrane loss increased deforming pressure from 9.0 ± 0.4 mm H₂O for control cell to 190 ± 21 for cell fragmented in two steps by the micropipette and 120 ± 20 for heat-fragmented cells as compared to 405 ± 39 for metabolically depleted cells and 203 ± 9 for cells stored 8 weeks in acid citrate dextrose (ACD) solution at 4°C. The volume of the micropipette fragmented cells, heat-induced spheres and blood bank cells were less than control erythrocytes (78 μ ³, 82 μ ³ and 79 μ ³ vs 87 μ ³) and volume of the metabolically depleted cells did not differ from control. The loss of deformability in the fragmentation induced spheres appears to be related to sphericity; in blood bank spheres it is thought to relate to membrane loss and abnormal intracellular ATP/Ca²⁺, and in the metabolically depleted cells which have not lost membrane area, rigidity is thought to be due to Ca²⁺-induced contraction of membrane proteins and gel transition of proteins at the inner membrane surface as ATP is depleted. Chlorpromazine, known to increase membrane surface area, did not reverse the rigidity of the spheres.