Solubilização de membranas de eritrocitos por surfactantes da serie Tween

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Surfactants present hemolytic effects and depending on their concentration, they can either protect or solubilize erythrocyte membrane. In this work we have studied the interaction of nonionic surfactants from the Tween series (polyoxyethylenesorbitan) with human erythrocytes membranes. Triton Xl00 (t-octylphenoxypolyethoxyethanol) was used as a control, in hemolytic assays. To assure the purity and structural composition of the surfactants we employed CMC determination and lH-NMR characterization. Hemolytic studies with human erythrocytes (Ht 5 - 20%) showed that surfactants from the Tween series (20,40 and 80) have a protective and Iytic effect upon the membrane above their respective CMCs (59, 27 and 12 _), while Triton Xl00 presents those effects at its CMC range (0,25 mM). The "protection" assays were carried out in a hypotonic media (NaCI 77mM) and the Iysis experiments in isotonic conditions. In both assays Hb release from the erythrocyte was spectrophometrically measured. From the surfactant concentrations for protection (Ol Ot), onset (csat) and 100% hemolysis (csol) we determined the surfactant:lipid molar ratios for protection and Iysis (RProt, Rsat, R$OI respectively). At isotonic condition we measured also the release of intracelular K " (by potenciometry) as an alternative method for quantifying hemolysis. As well as Hb release measurements, the assays of K "-release showed to be quite adequate for the study of hemolysis. There is a good correlation between csat and csol values obtained by the two techniques, although K "-release occurs at lower surfactant concentrations than Hb-release. In extremely high concentrations, these surfactants induce Hb oxidation, being Tween 80 the one with the highest oxidative power, in comparison to the other Tweens (Tween 80 >Tween 40 >Tween 20). Triton X100 does not oxidise Hb. The oxidative effect of Tween 80 prevented the determination of Rso1 values in the highest Hts. The treatment proposed by Lichtenberg (1985) for the quantification of surfactant:membran ratios for solubilization was not found adequate for the analysis of the hemolytic effect of Tweens, which R values are very high, characterizing them as weak solubilizers

ASSUNTO(S)

hemoglobina detergentes eritrocitos membranas (biologia)

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