[ATP-dependent and ATP-independent changes in deformability of human erythrocytes]

By means of a simple filtration procedure it is shown that the deformability of red blood cells depends indirectly on their relative ATP-concentration. Losses in deformability were observed even with concentrations of ATP, which occur in the course of normal ageing of red blood cells in situ. If erythrocytes are incubated for longer times, their membrane is alterated to such a degree, that the changes cannot be reversed solely by restitution of ATP. The cells remain rigid.