Ca2+ Permeability and Cytosolic Ca2+ Concentration Are Not Impaired in β-Thalassemic and Hemoglobin C Erythrocytes

• Published in: Blood 1987-09, Vol.70 (3), p.804-808
• Main Authors: Rhoda, M.D., Galacteros, F., Beuzard, Y., Giraud, F.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - blood; Anemias. Hemoglobinopathies; Biological and medical sciences; Calcium - blood; Cell Membrane Permeability; Cytosol - metabolism; Diseases of red blood cells; Erythrocytes - metabolism; Hematologic and hematopoietic diseases; Hemoglobin C Disease - blood; Humans; Medical sciences; Osmolar Concentration; Thalassemia - blood
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V70.3.804.804

Total calcium content, determined by atomic absorption spectroscopy, Ca2+ influx, and cytosolic free Ca2+ concentration ([Ca]1), estimated by a method involving the incorporation of a Ca2+ chelator (Quin 2), were measured in erythrocytes from β-thalassemic (β-thal) and hemoglobin C (CC) patients. Elevation of the total calcium content was observed in the cells from all patients, particularly in CC and splenectomized β-thal. However, [Ca]1 was within the normal range (-25 nmol/L) in all the pathologic cells. Ca2+ influx in CC cells and in cells from nonsplenectomized β-thal patients was also within the same range as that observed in control erythrocytes. In cells from splenectomized β-thal patients, the kinetic of 45Ca influx was biphasic, indicating the existence of two pools of exchangeable Ca2+. Density fractionation of the cells from one splenec- tomized β-thal patient showed that the rapid pool corresponded to the lightest cell fraction, which was also found to have the highest calcium content. The dense cells exhibited a normal Ca2+ influx as well as a smaller increase in total calcium content. It is suggested that, as in sickle cell anemia, the excess of Ca2+ in β-thal cells is not free in the cytoplasm but trapped within endocytic vacuoles, especially in a population of abnormal cells that are normally removed by the spleen. In CC patients, who have a functional spleen, a different mechanism could be responsible for the calcium retention. In conclusion, the present results demonstrate that in these two cases of hemolytic anemia associated with high calcium content, Ca2+ permeability and the level of cytosolic Ca2+ are normal.© 1987 by Grune & Stratton, Inc.0006-4971/87/7003-0031$3.00/0