Interference of H2O2 with stimulus-secretion coupling in mouse pancreatic β-cells
Interference of H2O2 with stimulus-secretion coupling in mouse pancreatic β-cells
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DOI：
10.1111/j.1469-7793.1999.471ae.x
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发表时间：
1999-01-15
影响因子：
5.5
通讯作者：
Drews, G
中科院分区：
文献类型：
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作者：
Krippeit-Drews, P;Krämer, C;Drews, G
1.我们以前曾报道过，在小鼠胰腺β-细胞H2 O2超极化膜，并增加记录在膜片钳技术的穿孔膜片配置的ATP敏感的K+电流。本研究旨在阐明其潜在机制.通过化学发光测量的细胞内ATP浓度被H2 O2降低。ADP浓度在前10 min内平行增加，导致ATP/ADP比值显著降低.与这些结果一致，H2O2.4抑制了葡萄糖刺激的分离胰岛的胰岛素分泌。膜超极化测量与细胞内微电极在完整的胰岛和抑制胰岛素分泌被抵消甲苯磺丁脲，表明通道仍然响应于抑制剂和ATP浓度不太低，触发胞吐。然而，β细胞对甲苯磺丁脲的敏感性在用H2O2.5处理后降低。H_2O_2使细胞内Ca ~（2+）活性（[Ca ~（2+）]（i））呈双相性增加。[Ca 2 +]（i）的第一次短暂升高是由于细胞内储存的Ca 2+的动员，随后是持续的增加，这至少部分依赖于Ca 2+内流。第一阶段似乎反映了Ca 2+从Ca 2+中的迁移。我们的研究结果表明，过氧化氢干扰葡萄糖代谢，影响膜电位和ATP敏感的K+电流通过细胞内ATP浓度。这些事件最终导致胰岛素分泌的抑制，尽管[Ca 2 +]（i）增加。
1. We have reported previously that in mouse pancreatic beta-cells H2O2 hyperpolarizes the membrane and increases the ATP-sensitive K+ current recorded in the perforated patch configuration of the patch-clamp technique. The present study was undertaken to elucidate the underlying mechanisms.2. The intracellular ATP concentration measured by chemoluminescence was reduced by H2O2. The ADP concentration increased in parallel during the first 10 min, resulting in a pronounced decrease in the ATP/ADP ratio.3. Consistent with these results, glucose-stimulated insulin secretion from isolated islets was inhibited by H2O2.4. Membrane hyperpolarization measured with intracellular microelectrodes in intact islets and inhibition of insulin secretion were counteracted by tolbutamide, indicating that the channels are still responsive to inhibitors and that the ATP concentration is not too low to trigger exocytosis. However, the sensitivity of the beta-cells to tolbutamide was reduced after treatment with H2O2.5. H2O2 increased the intracellular Ca2+ activity ([Ca2+](i)) in a biphasic manner. A first transient rise in [Ca2+](i) due to mobilization of Ca2+ from intracellular stores was followed by a sustained increase, which was at least partly dependent on Ca2+ influx. The first phase seems to reflect Ca2+ mobilization from mitochondria.6. Our results demonstrate that H2O2 interferes with glucose metabolism, which influences the membrane potential and ATP-sensitive K+ current via the intracellular concentration of ATP. These events finally lead to an inhibition of insulin secretion despite an increase in [Ca2+](i).