论文部分内容阅读
采用全细胞膜片钳技术观察不同浓度葡萄糖对新生Wister大鼠胰岛β细胞膜上电压依赖性L-型钙离子通道门控特性的影响,即分别用2.8、5.5、16.7和22.2mmol/L的葡萄糖刺激单个贴壁胰岛β细胞,以Ba2+作为载流子,分析比较葡萄糖对L-型钙通道电流的影响。结果显示:在低糖(2.8mmol/L)情况下,大鼠胰岛β细胞电压依赖性L-型钙离子通道电流静息膜电位约为-70mV,钙离子内流不明显,且无明显的时间依赖性关系。在葡萄糖浓度为5.5mmol/L的条件下,大鼠胰岛β细胞电压依赖性L-型钙离子通道电流在-40mV激活,+20mV左右达峰值;高糖(16.7mmol/L)作用胰岛β细胞后,电压依赖性L-型钙离子通道电流约-40mV激活,+10mV左右达峰值,即峰值电位向负方向移动约10mV;葡萄糖浓度达22.2mmol/L时,电活动呈持续性去极化,峰值电位增加不明显,提示葡萄糖降低胰岛β细胞电压依赖性L-型钙通道电流的激活电位阈值,促进其开放,钙电流峰值电位增加,随着高糖作用时间的延长,胰岛β细胞容积变大,细胞膜破坏。提示高浓度葡萄糖在一定范围内可以刺激胰岛素的分泌,但浓度过高则可抑制胰岛素的分泌,通过观察葡萄糖刺激的胰岛β细胞胰岛素第一时相分泌的变化,在一定程度上对高糖毒性作用的可能提供了证据。
Whole-cell patch-clamp technique was used to observe the effects of different concentrations of glucose on the voltage-dependent L-type calcium channel gating characteristics in islet β-cell membranes of neonatal Wister rats, ie, glucose stimulation with 2.8, 5.5, 16.7 and 22.2 mmol / Single adherent islet β cells, Ba2 + carrier as a carrier, analysis and comparison of glucose on L-type calcium channel current. The results showed that under low glucose (2.8mmol / L), the resting membrane potential of pancreatic β-cell voltage-dependent L-type calcium channel current was about -70mV, the influx of calcium ions was not obvious, and there was no obvious time Dependency. Under the glucose concentration of 5.5 mmol / L, the voltage-dependent L-type calcium channel current of pancreatic islet β cells was activated at -40 mV and peaked at about +20 mV; the high glucose (16.7 mmol / L) , The voltage-dependent L-type calcium channel current was activated at about -40mV and peaked at about + 10mV, that is, the peak potential shifted about 10mV in the negative direction. When the glucose concentration reached 22.2mmol / L, the electrical activity showed a sustained depolarization , The peak potential increase is not obvious, suggesting that glucose reduces the activation potential threshold of islet β cell voltage-dependent L-type calcium channel current to promote its opening, the peak current potential of calcium increased with the extension of the role of high glucose, β-cell volume Larger, cell membrane damage. Suggest that high concentration of glucose can stimulate insulin secretion within a certain range, but the concentration is too high can inhibit the secretion of insulin by observing the glucose-stimulated islet β-cell insulin secretion of the first phase, to some extent, high glucose toxicity The possible role provides evidence.