Osmolality Threshold for Erythrocyte Hemolysis

Abstract

In this study, we defined the minimum osmolality threshold for normal and sickle red cell hemolysis. Postmortem findings from water intoxication deaths are limited to edema of the brain and lungs with osmolality of 108 mEq/L (216 mOsm/kg), which is far lower than the physiological osmolality of 135-145 mEq/L (270-295 mOsm/kg). We investigated whether such low osmolality had any effect on the integrity of the erythrocyte membrane and to what extent. We hypothesized that red cell membrane's ability to deform/reform under shear confirms that the cell is highly resistant to changes in serum osmolality. Appropriately, collected whole blood was centrifuged to separate plasma from red cells. The packed cells were washed three times and resuspended (~25% hematocrit) in isotonic solution. A total of 50 μl of the 25% suspension was incubated in solution ranging from 290 to 65 mOsm/kg sodium chloride. Following incubation, the supernatant and pellets were analyzed for hemoglobin (spectrometry) and glycophorin A content by using Western blotting techniques. Red cells hemolyzed when osmolality dropped to less than 95 mEq/L (190 mOsm/kg) and 170 mOsm/kg for normal