Membrane fluidity and activity of membrane ATPases in human erythrocytes under the influence of polyhydroxylated fullerene

The influence of fullerenol on the activities of human erythrocyte membrane ATPases and the fluidity of the plasma membrane as well as the possibility of fullerenol incorporation into the plasma membrane were investigated. Fullerenol at concentrations up to 150 μg/mL induced statistically significant decreases in the anisotropy of 1-anilino-8-naphthalene sulfonate (ANS) (14%), N,N,N-trimethyl-4-(6-phenyl-1,3,5,-hexatrien-1-yl)phenylammonium p-toluenesulfonate (TMA-DPH) (7.5%) and 1,6-diphenyl-1,3,5-hexatriene (DPH) (9.5%) after a 1-hour incubation at 37 °C. The effect disappeared for ANS and TMA-DPH, but not for DPH, after washing out the fullerenol. Incubation of erythrocyte membranes with fullerenol led to decreases in the activities of Na+,K+-ATPase (to 23% of the control value), Ca2 +-ATPase (to 16% of control) and Mg2 +-ATPase (to 22% of control). Washing out the fullerenol lessened the inhibition of the Na+,K+-ATPase (37% of control) and Ca2 +-ATPase (23.5% of control); however, it did not influence Mg2 +-ATPase activity. Furthermore, fullerenol could associate with erythrocyte plasma membranes.Our results suggest that fullerenol associates primarily with the surface of the plasma membrane; however, it can also migrate deeper inside the membrane. Moreover, fullerenol influences membrane ATPases so that it may modulate ion transport across membranes.

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► Fullerenol C60(OH)~ 30 decreases the fluidity of the erythrocyte plasma membrane.
► Fullerenol binds mostly to the surface of the erythrocyte membrane.
► Fullerenol can incorporate into the hydrophobic region of the erythrocyte membrane.
► The activity of membrane ATPases was decreased irreversibly by fullerenol.
► The direct and indirect mechanisms of fullerenol binding for membrane ATPases are proposed.