Accumulation of methylene blue by erythrocytes and determination of its maximum sensitivity to cell damage

The accumulation of methylene blue in native and damaged erythrocytes treated by cetyltrimethylammonium bromide at different initial concentrations (c0) of methylene blue and different volume ratios between external solution and cells (Vs/Vc) was studied. It was shown that at low methylene blue concentrations (c0 < 200 microM), the sorption of the dye by cells made the main contribution to its accumulation. As a result, the internal concentration of methylene blue exceeded manifold its external concentration and their ratio Q was 4-6 for native and 6-9 for damaged cells. As Vs/Vc decreased and especially as c0 increased, the diffusion of methylene blue inward the cells increased concentration gradient, and Q sharply fell to 0.9-1.0. The optimal values of c0 and Vs/Vc that provide the maximum sensitivity of Q to cell damage were determined. The advantages of using Q over other parameters of methylene blue accumulation were shown.