Compartmentalization of Ca2+ in sickle cells

Cell Calcium
M D RhodaY Beuzard

Abstract

Control (AA) and sickle cell anemia (SS) erythrocytes were loaded with Ca-chelator (Quin2 or Benz2) to increase the cellular exchangeable Ca2+ pool and to measure the Ca2+ exchange fluxes and the cytosolic ionized Ca2+ ([Ca]i) (Lew et al., 1982, Nature, 298, 478). The chelator incorporation induced a decrease in the ATP content which was smaller in SS than in AA cells and partially reversible upon reincubation in a chelator-free medium. The amount of trapped chelator was determined by two methods: 45Ca binding to the chelator in Ca-ionophore treated cells in Ca-EGTA buffers and [3H]Quin2 incorporation. A slight over-estimation of the chelator content was found with the second method but incorporation was the same in both types of cells. The kinetics of 45Ca equilibration and 45Ca release were used to measure Ca2+ fluxes and [Ca]i in oxygenated chelator-loaded cells. SS cells, as compared to AA cells, exhibited a moderate increase in Ca2+ fluxes (30-75%) but [Ca]i remained in the same range (about 20 nM). Thus the excess of Ca2+ found in SS cells is not available for the Ca2+ pump or the K+ channel a conclusion in agreement with that of Bookchin et al. (1984, Cell Calcium, 5, 277). Analysis of the 45Ca kinetics showed that in AA...Continue Reading

Citations

Sep 1, 1993·Journal of Fluorescence·H SzmacinskiM L Johnson
Feb 19, 1993·Neuroscience Letters·J M Dubinsky
Nov 1, 1994·Biophysical Journal·R M Johnson
Nov 13, 1991·Biochimica Et Biophysica Acta·A J Schroit, R F Zwaal
Feb 22, 2013·Blood Reviews·Giampaolo MinettiLars Kaestner
Jun 30, 1992·Biochimica Et Biophysica Acta·R M Johnson, K Tang

Related Concepts

Quin2-acetoxymethyl ester
Benz2-am
DNA-dependent ATPase
Aminoquinolines
Anemia, Sickle Cell
Calcium
Cell Compartmentation
Metal Antagonists
Protoplasm
Abnormal Red Blood Cell

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