Parameters of bioimpedance spectroscopy in young and old erythrocytes

The parameters of bioimpedance spectroscopy (BIS) were studied in suspensions of young and old erythrocytes. The separation of erythrocytes according to age in a density gradient was performed. The BIS parameters, including the extracellular (Re) and intracellular (Ri) fluid resistances, characteristic frequency (Fchar), cell membranes’ capacitance (Cm), and the Alpha parameter of concentrated suspensions of young and old erythrocytes (n = 6) were measured using an ABC-01 Medass bioimpedance analyzer in the frequency range 5–500 kHz. Re (300.4 ± 30.0 and 261.2 ± 21.8 Ω in old and young erythrocytes, respectively, p < 0.05), Ri (86.6 ± 9.1 Ω and 73.4 ± 7.3 Ω in old and young erythrocytes, respectively, p < 0.001), and Alpha (0.305 ± 0.003 and 0.302 ± 0.001 in old and young erythrocytes respectively, p < 0.05) were greater in the suspension of old erythrocytes than in the suspension of young erythrocytes; and Fchar (308.3 ± 42.0 kHz and 347.4 ± 48.0 kHz in old and young erythrocytes, respectively, p < 0.05) and Cm (99.3 ± 10.1 pF and 112.8 ± 6.3 pF in old and young erythrocytes, respectively, p < 0.01) were less in the suspension of old erythrocytes than in the suspension of young erythrocytes. These differences between the BIS parameters of old and young erythrocytes were possibly due to the structural change in erythrocytes during aging (an increase in the concentration of intracellular hemoglobin, the change in the shape of the erythrocyte, their converging due to the decrease in cellular negative surface charge, and an increase in membrane permeability to ions). Thus, the BIS parameters depend on the erythrocyte age composition.