PubMed · 8043930
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E Shinar, E A Rachmilewitz. 1993. Haemoglobinopathies and red cell membrane function.. https://doi.org/10.1016/s0950-3536(05)80150-7
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The percentage of normal, red blood cells that are hemolyzed when placed in hypotonic solutions depends on a variety of factors, two important ones being the initial sphericities of the cells and the tonicities to which they are subjected. Other, less well-understood factors that are important in hemolysis are the initial cell volumes, how much free water they contain and the elasticity of the cell membranes. The purpose of this work is to identify the constraints a red cell must satisfy in order to be hemolyzed. Human erythrocyte data is used in a physical model that compares the balance of hydrostatic stresses in sphered cells that are on the verge of hemolysis. For hemolysis to occur we find there is a critical sphericity index that must be exceeded. It depends on tonicity, the initial, fractional water volume in the cells and the maximum fractional area dilation the cell membranes can withstand. Membrane tensile strength and the non-ideal osmotic behavior of hemoglobin are of relatively minor importance. But when they are taken into account, the hemolysis constraint, in the form of a remarkably simple inequality, compares favorably with clinical tests of erythrocyte osmotic fragility.
We report here a quick and inexpensive method for preparing standards of known fluorochrome content for calibration and quantitation of flow cytometry fluorescence signals. Erythrocyte ghosts prepared by hypotonic lysis are filled with solutions containing fluorescently labeled dextran. Standards prepared by this technique have a narrow range of fluorescence and a linear response of fluorescence to fluorochrome content up to 2 x 10(6) fluorochrome molecules/cell. The volume of ghost standard particles is roughly 70 femtoliters (fl)/cell. The fluorescence of ghost standards is nearly identical to that of commercially available microbead standards of similar fluorochrome content. Ghost standards have stable fluorescence for at least 3 weeks at 4 degrees C. These standards can be made with any fluorochrome or combination of fluorochromes over a wide concentration range.
UNLABELLED: One of the causes of early onset hyperkalaemia in very low birth weight infants is presumed to be the dysfunction of K+ transport across the cell membrane. Sodium-potassium adenosine triphosphatase(Na(+)-K+ ATPase) is known to play a major role in K+ transport. We compared the concentrations of erythrocyte Na(+)-K+ ATPase (Vmax levels) for hyperkalaemic and normokalaemic infants of matched gestational age. In hyperkalaemic infants, the highest levels of Vmax were reached at 24-48 h after birth, but in normokalaemic infants, there were no significant changes in Vmax levels during the 1st week after birth. At 12-72 h after birth, erythrocyte K+ concentrations for hyperkalaemic infants were higher than those of normokalaemic infants. For both groups of infants, the highest levels of plasma K+ during the 1st week after birth showed a positive correlation with those of Vmax. CONCLUSION: Na(+)-K+ ATPase on the cell membrane is activated to compensate for hyperkalaemia; however, when this compensation is incomplete, hyperkalaemia occurs.