Editor's foreword

Abstract

Human red cells were exposed to hypertonic solutions of sucrose for 1 hr at 0 °C to investigate the effects on cation leaks of hypertonic conditions with a nonpermeating cryoprotective additive producing a lower ionic strength at a given osmolality than when sodium chloride alone is present. All sucrose solutions also contained the same concentration of sodium chloride that is present in isotonic sodium chloride. In addition to the measurement of cell water, and sodium and potassium by atomic absorption spectrophotometry, the possible uptake of sucrose was studied using 14C as a marker.The results showed that cell shrinkage was identical in hypertonic sucrose and sodium chloride and that hypertonic sucrose did not induce a cation leak at a lower osmolality than did sodium chloride. In both circumstances the potassium leak begins at about 2000 mosmolal. There is no significant uptake of sucrose into the cells even when the cation leaks have been established. A small inward leak of sodium begins in hypertonic sodium chloride but not in sucrose by 1000 mosmolal but this may be related to the high g used for cell separation. The membrane potential when the cation leak begins is of a different sign in hypertonic sucrose to that of hypertonic salt.The results suggest that nonpenetrating cryoprotective agents do not modify the osmolality (temperature) during freezing at which the membrane of the red cell becomes leaky to cations. Instead, they reduce the extracellular concentration of cation and thus reduce the concentration gradient that is able to take advantage of the leak.