Modulation of calcium channels in human erythroblasts by erythropoietin
Modulation of calcium channels in human erythroblasts by erythropoietin
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DOI：
10.1182/blood.v89.1.92.92_92_100
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发表时间：
1997-01-01
期刊：
影响因子：
20.3
通讯作者：
Miller, BA
中科院分区：
文献类型：
--
作者：
Cheung, JY;Zhang, XQ;Miller, BA
Erythropoietin (Epo) induces a dose-dependent increase In intracellular free Ca2+ [[Ca2+](i)] in human erythroblasts, which is dependent on extracellular Ca2+ and blocked by high doses of nifedipine or Ni2+, in addition. pretreatment of human erythroblasts with mouse antihuman erythropoietin receptor antibody but not mouse immunopure IgG blocked the Epo-induced [Ca2+](i) increase, indicating the specificity of the Ca2+ response to Epo stimulation. in this study, the erythropoietin-regulated calcium channel was identified by single channel recordings. Use of conventional whole cell patch-clamp failed to detect Epo-induced whole cell Ca2+ current. To minimize washout of cytosolic constituents, we next used nystatin perforated patch, but did not find any Epo-induced whole cell Ca2+ current. Using Ba2+ (30 mmol/L) as charge carrier in cell-attached patches, we detected single channels with unitary conductance of 3.2 pS, reversal potential of +72 mV, and whose unitary current (at +10 mV) increased monotonically with increasing Ba2+ concentrations. Channel open probability did not appreciably change over the voltage range (-50 to +30 mV) tested. Epo (2 U/mL) increased both mean open time (from 4.27 +/- 0.75 to 11.15 +/- 1.80 ms) and open probability (from 0.26 +/- 0.06 to 2.56 +/- 0.59%) of this Ba2+-permeable channel. Our data strongly support the conclusion that the Epo-induced [Ca2+](i) increase in human erythroblasts is mediated via Ca2+ entry through a voltage-independent Ca2+ channel. (C) 1997 by The American Society of Hematology.
