Thermal Properties and Fluidity of Human Erythrocyte Membranes in Diabetes Mellitus

Exposure of human erythrocytes to elevated temperatures induces a decrease in stability of the cell membrane. Thermally induced haemolysis of erythrocytes from patients with type 1 diabetes and from healthy control individuals was measured as a function of duration of exposure to heat between 48.0 and 54.0 degrees C. Results indicate that the thermosensitivity of erythrocytes from patients with type 1 diabetes is lower than for control individuals. Activation energies for lysis were similar for both control and 'diabetic' erythrocytes, being 298.3 and 287.7 kJ/mol, respectively. The steady-state fluorescence anisotropy measurement of TMA-DPH for each step of haemolysis was employed as a parameter characterizing membrane fluidity. We found that 'diabetic' erythrocyte membranes had significantly decreased fluidity. The relationship between fluidity and rate of haemolysis indicates that the rate-limiting step in the haemolysis reaction involves the rupturing of the membrane bilayer.