Depolarization-evoked Ca<SUP>2+</SUP> release in a non-excitable cell, the rat megakaryocyte

作     者：Mahaut-Smith, MP Hussain, JF Mason, MJ 

作者机构：Univ Cambridge Dept Physiol Cambridge CB2 3EG England 

出 版 物：《JOURNAL OF PHYSIOLOGY-LONDON》 (生理学杂志)

年 卷 期：1999年第515卷第2期

页      面：385-390页

核心收录：

学科分类：0710[理学-生物学] 1001[医学-基础医学(可授医学、理学学位)] 07[理学] 071003[理学-生理学] 

主　　题：腺苷二磷酸/药理学 钙/代谢 电生理学 肝素/药理学 细胞内膜/代谢 巨核细胞/代谢 巨核细胞/生理学 膜电位/药物作用 容积渗克分子浓度 膜片钳术 大鼠 Wistar 受体 嘌呤能/药物作用 受体 嘌呤能/代谢 钠/药理学 动物 男(雄)性 大鼠 

摘      要：1. The effect of membrane potential on [Ca2+](i) in rat megakaryocytes was studied using simultaneous whole-cell patch clamp and fura-2 fluorescence recordings. 2. Depolarization from -75 to 0 mV had no effect on [Ca2+](i) in unstimulated cells, but evoked one or more spikes of Ca2+ increase (peak increase: 714 +/- 95 nM) during activation of metabotropic purinoceptors by 1 mu M ADP. 3. The depolarization-evoked Ca2+ increase was present in Ca2+-free medium and also following removal of Na+. Thus depolarization mobilizes Ca2+ from an intracellular store without a requirement for altered Na+-Ca2+ exchange activity. 4. Intracellular dialysis with heparin blocked the depolarization-evoked Ca2+ increase, indicating a role for functional IP3 receptors. 5. Under current clamp, ADP caused the membrane potential to fluctuate between -43 +/- 1 and -76 +/- 1 mV. Under voltage clamp, depolarization from -75 to -45 mV evoked a transient [Ca2+](i) increase (398 +/- 91 nM) during exposure to ADP. 6. We conclude that during stimulation of metabotropic purinoceptors, membrane depolarization over the physiological range can stimulate Ca2+ release from intracellular stores in the rat megakaryocyte, a non-excitable cell type, This may represent an important mechanism by which electrogenic influences can control patterns of [Ca2+](i) increase.