Changes in erythrocyte aggregation and deformability during human ageing

Blood flow through the cardiovascular system is associated with erythrocyte aggregation and deformability. This study is aimed at determining the changes in these parameters associated with human ageing. Blood samples of healthy subjects of different age groups (ranging from 20 to 65 years) were obtained by venepuncture in test tubes containing citrate phosphate dextrose as an anticoagulant. The aggregation of erythrocytes, a reversible process, was determined by the changes in laser-transmitted intensity during gravitational sedimentation of erythrocytes and their formed aggregates. The deformability of erythrocytes was measured by the filtration of erythrocyte suspension through cellulose membrane. The erythrocyte aggregation increases significantly (P less than or equal to 0.008) in age groups III (41-50 years) and IV (51-65 years) compared to that of controls (20-30 years). In contrast to this, the erythrocyte deformability in these groups compared to that of the control group, is significantly (P less than or equal to 0.04) reduced. These haemorheological changes may lead to disturbed blood flow, and thus could contribute to the increased incidence of circulatory disorders in the elderly.