Erythrocyte calcium metabolism. Calcium exchange in normal and sickle-cell-anaemia erythrocytes.
Under exchange conditions (no net increase in calcium), erythrocytes incubated in isoosmotic phosphate-buffered saline have an exchangeable calcium pool comprising about 10% of the total erythrocyte calcium. This pool reaches exchange equilibrium, for either inward-directed or outward-directed transfer of the 45Ca-exchange label, with a half-time of about 20 min. The uptake of Ca2+ requires phosphate, even under hypo-osmotic conditions, where the calcium loading expected as the cells swell is obtained only when phosphate is present. The phosphate requirement is not due to Ca2+ transport as a phosphate salt. This exchangeable-calcium pool is also present in sickle-cell-anemia erythrocytes, and comprises a similar proportion of total cellular calcium.
D000755:Anemia, Sickle Cell / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D004913:Erythrocytes, Abnormal / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D010710:Phosphates; D012964:Sodium; D002118:Calcium