Osmolality Threshold for Sickle Cell Erythrocyte Hemolysis
Victoria M Richardson1, Kay Woollen, MT1, William A Anong1,2*
Journal Title: Journal of Clinical Medical Research
Background: The importance of fluid intake is well document as metabolic and physiological processes operate effectively in a homeostatic environment. Normal red cells are more resilient to changes in serum osmolality compared to other cells, remaining intact when serum osmolality decreases to as low as 190-mOsM from the 270-290-mOsM reference interval. The membrane’s ability to deform/reform under shear confers the red cell high resistant to changes in serum osmolality. Although normal red cells are resilient, the osmolality threshold for hemolysis of abnormal red cells such as sickle cell blood remains unclear. The primary objective of this study was to determine the osmolality threshold for hemolysis of sickle cell blood vis-a-vis that of normal red cells.
Methods: As described under methods, red cells were prepped and exposed to solution of varying osmolality ranging from 290 to 65-mOsm of sodium chloride. Following incubation, the supernatant and pellets were analyzed for hemoglobin (spectrometry) and Glycophorin A (GPA) content by western blotting techniques.
Results: While the osmolality threshold for normal red cells was 190-mOsM, sickle erythrocytes osmolality threshold for hemolysis was surprisingly 170-mOsM. Both cells ruptured rapidly displaying an S-shaped-like “cooperativity” pattern. Complete (100%) hemolysis occurred at ≤150-mOsM. The hemoglobin retained in pellets decreased to ~50% (normal red cells) and ~20% (sickle red cells) when solution osmolality drops to 65-mOsM.
Conclusion: Sickle cell erythrocytes are more resilient than normal red cells to serum osmolality changes. This finding provides insight into how normal and sickle cell individuals would withstand changes in serum osmolality during dehydration/rehydration states. To alleviate pain, intravenous ï¬‚uids are routinely administered as adjuvant therapy to slow or reverse the sickling process. Hence, balancing electrolytes and fluid volume during acute pain episodes may significantly benefit African American who are disproportionately afflicted by the sickle cell disease.