The effects of mitomycin-C and temperature on dynamical properties of human erythrocyte membrane.

Alterations produced by mitomycin-C (hereafter MC) and temperature changes in human erythrocyte membrane molecular dynamics were studied, in vitro, by spin-labeling ESR technique. Erythrocyte cells were spin-labeled with 5- and 16-doxyl-stearic acids, 5- and 16-DSA, respectively, and membrane fluidity was quantified by measuring the changes in the order parameter (S), correlation time (tau), phase transition temperature and activation energies. Erythrocyte cells were first labeled with 5-DSA and 16-DSA at 37 degrees C for 10 min, then they were treated with MC of three different concentrations (2.5; 5 and 10 microM) for various time (0-300 min) at the same temperature. Experimental results indicate that treatment time and applied MC concentrations do not produce any significant reproducible changes in the spectral parameters. However, change in temperature was observed to alter significantly S and tau parameters that show biphasic character in the temperature range of 5-50 degrees C. Activation energy values of hydrocarbon chains above and below transition temperatures for untreated and MC-treated erythrocyte cells were also determined, and the effect of MC on these energy values were discussed.