Efeitos de combinações de hidrocloreto de guanidina, etanol, calor e hipotonicidade na estabilidade de membrana de eritrócitos humanos

Abstract

The stability of the erythrocyte membrane can be monitored by the amount of lysis by chaotropic agents such as heat, hypotonicity, guanidine hydrochloride and ethanol. This paper studies the effects of combinations of chaotropic, two by two, on the stability of human erythrocytes. We used erythrocytes from blood samples taken from 10 female healthy volunteers (26 ± 4 years old). The stability of erythrocytes was assessed by the half-transition points of curves of lysis produced by guanidine hydrochloride, ethanol and hypotonic stress, obtained by regression analysis of the sigmoidal dependencies of the absorbance at 540 nm with the concentration of each chaotropic agent, after incubation for a fixed time of 30 minutes. The results were compared by analysis of variance using the Tukey test. The combinations of guanidine hydrochloride with ethanol or heat produced synergistic chaotropic effects on the lysis of erythrocytes and on the denaturation of hemoglobin. But using 0.1 to 0.6 M guanidine hydrochloride caused protection of erythrocytes against hypotonic stress. This protective effect should be due to the saline nature of guanidine hydrochloride. Protection against lysis was also partly observed in the presence of 0.9 but not 1.0 M guanidine hydrochloride, where the effect of chaotropic agent predominated. Increases between 20 and 50 °C in temperature have also been associated with slight but significant protection of human erythrocytes against hypotonic stress.