• B14 fibroblasts;
  • NIH 3T3 fibroblasts;
  • membrane fluidity;
  • doxorubicin;
  • aclarubicin;
  • mitoxantrone;
  • fluorescence anisotropy;
  • ESR

The aim of this study was to examine the effect of three structurally different anticancer drugs—the pro-oxidative anthracyclines doxorubicin (DOX) and aclarubicin (ACL), and antioxidative anthraquinone mitoxantrone (MTX) on the fluidity of plasma membrane of immortalized rodent fibroblasts using fluorescence spectroscopy and electron spin resonance (ESR) techniques. Two kinds of fluorescent probes (TMA-DPH and 12-AS) and spin labels (5-DS and methyl-12-DS) were used to monitor fluidity in the hydrophobic core and in the polar headgroup region of the lipid bilayer. Immortalized hamster B14 and NIH 3T3 mouse fibroblasts were exposed to DOX, ACL and MTX. We demonstrate that these drugs influence predominantly the hydrophobic core of the lipid bilayer, inducing significant decrease in its fluidity at low concentrations (2–5μm). A decreased membrane fluidity at the surface of the lipid bilayer was observed only at a higher concentration (20μm) of the drugs, which indicates that DOX, ACL and MTX intercalate mainly into the hydrophobic core of the membrane, thereby perturbing its structure.