TRPM7, a member of the melastatin subfamily of transient receptor potential channels, is suggested to be a potential candidate for a physiological Mg²⁺ channel. However, there is no direct evidence of Mg²⁺ permeation through endogenous TRPM7. To determine the physiological roles of TRPM7 in intracellular Mg²⁺ homeostasis, we measured the cytoplasmic free Mg²⁺ concentration ([Mg²⁺]_i) in TRPM7-silenced H9c2 cells. [Mg²⁺]_i was measured in a cluster of 8–10 cells using the fluorescent indicator, furaptra. TRPM7 silencing did not change [Mg²⁺]_i in Ca²⁺-free Tyrode’s solution containing 1 mM Mg²⁺. Increasing the extracellular Mg²⁺ to 92.5 mM raised [Mg²⁺]_i in control cells (1.56 ± 0.19 mM) at 30 min, while this effect was significantly attenuated in TRPM7-silenced cells (1.12 ± 0.07 mM). The Mg²⁺ efflux driven by Na⁺ gradient was unaffected by TRPM7 silencing. These results suggest that TRPM7 regulates the rate of Mg²⁺ influx in H9c2 cells, although cytoplasmic Mg²⁺ homeostasis at basal conditions is unaffected by TRPM7 silencing.

中文翻译：

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TRPM7 沉默减弱了心肌成肌细胞、H9c2 细胞中 Mg 2+ 的流入

TRPM7 是瞬时受体电位通道的褪黑素亚家族的成员，被认为是生理 Mg ²⁺通道的潜在候选者。然而，没有直接证据表明 Mg ²⁺通过内源性 TRPM7 渗透。为了确定 TRPM7 在细胞内 Mg ²⁺稳态中的生理作用，我们测量了TRPM7 沉默的 H9c2 细胞中细胞质游离 Mg ²⁺浓度（[Mg ²⁺ ] _i）。[Mg ²⁺ ] _i是使用荧光指示剂 furaptra 在 8-10 个细胞群中测量的。TRPM7 沉默没有改变Ca ^{2+ 中的}[Mg ²⁺ ] _i不含 1 mM Mg ^{2+ 的}Tyrode 溶液。将细胞外 Mg ²⁺增加到 92.5 mM 会在 30 分钟时提高对照细胞中的[Mg ²⁺ ] _i (1.56 ± 0.19 mM)，而这种影响在 TRPM7 沉默的细胞中显着减弱 (1.12 ± 0.07 mM)。由 Na ⁺梯度驱动的 Mg ²⁺流出不受 TRPM7 沉默的影响。这些结果表明，TRPM7 调节H9c2 细胞中 Mg ²⁺流入的速率，尽管基础条件下的细胞质 Mg ²⁺稳态不受 TRPM7 沉默的影响。