首页> 外文期刊>Life sciences >FUNCTIONAL COUPLING OF THE NA+/CA2+ EXCHANGER WITH CA2+ RELEASE FROM INTRACELLULAR STORES IN CULTURED SMOOTH MUSCLE CELLS OF GUINEA PIG ILEUM
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FUNCTIONAL COUPLING OF THE NA+/CA2+ EXCHANGER WITH CA2+ RELEASE FROM INTRACELLULAR STORES IN CULTURED SMOOTH MUSCLE CELLS OF GUINEA PIG ILEUM

机译:培养的豚鼠回肠平滑肌细胞中NA + / CA2 +交换子与细胞内钙离子释放的功能耦合

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摘要

The mechanism of increase in intracellular Ca2+ concentration ([Ca2+](i)) by removal of extracellular Nat, which phenomena were reported previously (Japan. J. Pharmacol. 63 83-91 1993), was investigated in cultured guinea pig ileum longitudinal muscle cells loaded with a fluorescent Ca2+ indicator, fura-2, by digital ratio imaging microscopy. Isotonic substitution of choline chloride for NaCl induced a transient increase in [Ca2+](i). The pretreatment of thapsigargin (0.5 mu M), but not nicardipine (10 mu M), suppressed the transient increase completely. In solutions containing micromolar concentrations of free Ca2+ (nominally Ca2+-free solution), the Na+-free induced transient increase was observed, but neither the second cell exposure to the Na+-free solution nor the following application of histamine increased [Ca2+](i), indicating that removal of extracellular Na+ releases Ca2+ from intracellular stores including inositol 1,4,5-trisphosphate (IP3)-releasable pools. The Na+-free-induced transient increase required the presence of more than micromolar concentrations of extracellular free Ca2+ and releasable Ca2+ within the stores, but ryanodine did not affect the transient increase. These results suggest that undetectable influx of Ca2+ by the reverse-mode action of the Na+/Ca2+ exchanger can release Ca2+ from the thapsigargin-sensitive intracellular stores including IP3-releasable pools. [References: 27]
机译:通过在豚鼠回肠培养的纵向肌肉中研究了通过去除细胞外Nat来增加细胞内Ca2 +浓度([Ca2 +](i))的机制,该现象先前已有报道(Japan。J. Pharmacol。63 83-91 1993)。通过数字比率成像显微镜,细胞中装有荧光Ca2 +指示剂fura-2。氯化胆碱等渗替代氯化钠会导致[Ca2 +](i)瞬时增加。 thapsigargin(0.5μM)而不是尼卡地平(10μM)的预处理完全抑制了瞬时增加。在含有微摩尔浓度的游离Ca2 +的溶液(名义上不含Ca2 +的溶液)中,观察到无Na +的诱导的瞬时增加,但第二次细胞暴露于无Na +的溶液或随后施加的组胺都不会增加[Ca2 +](i ),表明去除细胞外Na +会释放细胞内存储中的Ca2 +,包括肌醇1,4,5-三磷酸(IP3)释放池。无Na +引起的瞬时增加需要在存储中存在超过微摩尔浓度的细胞外游离Ca2 +和可释放的Ca2 +,但是碱不能影响瞬时增加。这些结果表明,通过Na + / Ca2 +交换子的逆向作用,无法检测到Ca2 +的大量涌入会从毒胡萝卜素敏感的细胞内存储(包括IP3可释放的池)释放Ca2 +。 [参考:27]

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