Previously detected β sp and γ1 sp dielectric relaxations on the spectrin-based membrane skeleton (MS) of human red blood cells (RBCs) have been shown sensitive to the attachment of MS to the lipid-protein membrane. Such relaxations were now detected on the MS of mammal (rat, horse, bovine, sheep and goat) and "unstrained" chicken RBCs. To become "unstrained" chicken RBCs were subjected consecutively to cold (4°C, >20 h) and either colchicine (15 mM) or vinblastine (30 μM) (4°C, 1 h) that led to irreversible disassembly of their marginal band and an additional portion of their cytoskeleton. With the exception of bovine RBCs, the critical frequency (f c) of either relaxation increased, although at different rates, with the decrease in the volume of RBC species. The strong increase in f c of γ1 sp relaxation from 2.5 MHz ("unstrained" chicken RBCs) to 13 MHz (goat RBCs) could indicate denser state of MS in smaller RBC species. The low values of f c of γ1 sp relaxation in "unstrained" chicken RBCs (2.5 MHz) and bovine RBCs (4.5 instead of 9 MHz) could be related to their extraordinary thermal stability at the temperature of spectrin denaturation.

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The effects of thioridazine (TDZ) and chlorpromazine (CPZ) and bovine serum albumin nanoparticles (BSA-NPs) on erythrocyte membranes have been investigated. Two kinds of hemolytic assays were used; hemolysis under hypotonic conditions and hemolysis in physiological conditions. Under hypotonic conditions for 50% hemolysis, both TDZ and CPZ have a biphasic effect on membranes; namely, stabilization at low concentrations and destabilization after reaching a critical concentration. In physiological conditions, there are other critical concentrations above which both drugs hemolyse the erythrocites. In each case, the critical concentrations of TDZ are lower than those of CPZ, which is consistent with the ratio of their partition coefficients. When BSA-NPs are added to the erythrocyte suspension simultaneously with the drugs, the critical concentrations increase for both drugs. The effect is due to the incorporation of a portion of drug substances into the BSA-nanoparticles, which consequently leads to the decrease of the active drug concentrations in the erythrocyte suspension medium. Similar values of the critical concentrations are found when the BSA-NPs are loaded with the drugs before their addition to the erythrocyte suspension in which case the events of the partition are: desorption of the drug from BSA-NPs, diffusion through the medium, and adsorption on erythrocyte membranes. This result suggests that the drugs are not influenced by the processes of adsorption and desorption onto and out of the BSA-NPs, and that the use of BSA-NPs as drug transporters would allow intravenous administration of higher doses of the drug without the risk of erythrocyte hemolysis.

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