Effects of temperature on water diffusion in human erythrocytes and ghosts — nuclear magnetic resonance studies

Abstract

The temperature-dependence of water diffusion across human erythrocyte membrane was studied on isolated erythrocytes and resealed ghosts by a doping nuclear magnetic resonance technique. The conclusions are the following: (1) The storage of suspended erythrocytes at 2 °C up to 24 h or at 37 °C for 30 min did not change the water exchange time significantly, even if Mn 2+ was present in the medium. This indicates that no significant penetration of Mn 2+ is taking place under such conditions. (2) In case of cells previously incubated at 37°C for longer than 30 min with concentrations of p- chloromercuribenzene sulfonate (PCMBS) greater than 0.5 mM, the water-exchange time gradually decreased if the cells were stored in the presence of Mn 2+ for more than 10 min at 37°C. (3) When the arrhenius plot of the water-exchange time was calculated on the basis of measurements performed in such a way as to avoid a prolonged exposure of erythrocytes to Mn 2+ no discontinuity occurred, regardless of the treatment with PCMBS. (4) No significant differences between erythrocytes and resealed ghosts regarding their permability and the activation energy of water diffusion ( E a,d ) were noticed. The mean value of E a,d obtained on erythrocytes from 35 donors was 24.5 kJ/mol. (5) The value of E a,d increased after treatment with PCMBS, in parallel with the percentage inhibition of water diffusion. A mean value of 41.3 kJ/mol was obtained for E a,d of erythrocytes incubated with 1 mM PCMBS for 60 min at 37°C and 28.3 kJ/mol for ghosts incubated with 0.1 mM PCMBS for 15 min, the value of inhibition being 46% and 21%, respectively.