Thermal dielectroscopy study of submembrane spectrin network in animal erythrocytes.

The shape and mechanical properties of mammalian erythrocytes depend on the conformational flexibility of their submembrane spectrin network. By contrast, avian erythrocytes are ovoid and nondeformable even though they also have such spectrin network. Using thermal dielectroscopy we isolated and studied erythrocytes from domestic mammals (cow, horse, dog and goat) and birds (chicken, turkey, pigeon and duck). Both erythrocyte suspension resistance and capacitance changed abruptly at the spectrin denaturation temperature, Td, determined with standard deviation of ± 0.2 °C. The frequency dependence of these changes occurring at Td, revealed the dielectric relaxation of dipoles, associated with the spectrin network. The critical frequency, fc, of this relaxation reflected the segmental mobility of spectrin while the Td corresponded to the thermal stability of spectrin. The spectrin network was more flexible and thermally labile in mammalian erythrocytes (fc and Td were 2–2.5 MHz and 50±1°C, respectively, compared to 0.6–1 MHz and 54±1 °C in avian erythrocytes). The species-related differences in Td and fc between mammals and birds were attributed to the cytoskeleton which existed in avian but was absent in mammalian erythrocytes.