Zhu Tie-Hong, Wang Yin-Xia, He Bing-Jun, Zang Jing-Jing, Liu Dong-Bo, Ding Xue-Mei
Department of Endocrinology, The General Hospital, Tianjin Medical University, Tianjin, China.
Zhonghua Nei Ke Za Zhi. 2009 Jun;48(6):488-91.
To observe the effect of amylin on the islet beta-cells voltage-gated L-calcium channels in rats.
Patch clamp technique was employed in the observation of the features and changes of electric current of islet beta-cells voltage-gated L-calcium channels before and after using amylin.
In the glucose environment of 5.5 mmol/L, the electric current of rat islet beta-cells voltage-gated L-calcium channels was activated at -40 mV and reached the peak at about +20 mV, with a peak value of about -120 pA and the insulin secretion level was (0.76 +/- 0.12) microg/L. Under the stimulation of glucose of 16.7 mmol/L, the peak current voltage moved to the left and increased up to - 140 pA and the level of insulin secretion measured (1.78 +/- 0.13) microg/L. Hatch islet beta-cells in amylin at the concentrations of 0.5, 1.0, 5.0 and 10.0 micromol/L, respectively. It was observed that in the 0.5 micromol/L and 1.0 micromol/L groups, there was no remarkable change in the peak potential activation voltage, current, and insulin secretion volume in comparison with the control group. However, in the environment of 5.5 mmol/L glucose, the increase of activation voltage of the 5.0 and 10.0 micromol/L groups was - 30 mV, with the peak current reduced to approximately -80 pA and -60 pA and the insulin secretion decreased to (0.49 +/- 0.11) microg/L and (0.36 +/- 0.12) microg/L respectively. Under the concentration of 16.7 mmol/L glucose, the activation voltage increased from -40 mV up to -30 mV and the peak current reduced to -80 pA and -40 pA. In the meantime, the insulin secretion decreased respectively to (1.20 +/- 0.13) microg/L and (0.89 +/- 0.14) microg/L, which is of significance.
The secretion of insulin is synchronized with the opening of the islet beta-cells voltage-gated L-calcium channels at the stimulation of glucose. The amylin inhibition of the insulin secretion is also synchronized with the opening of islet beta-cells voltage-gated L-calcium channels and it's in a positive concentration-dependent manner.
观察胰岛淀粉样多肽对大鼠胰岛β细胞电压门控L型钙通道的影响。
采用膜片钳技术观察使用胰岛淀粉样多肽前后胰岛β细胞电压门控L型钙通道电流的特征及变化。
在5.5 mmol/L的葡萄糖环境中，大鼠胰岛β细胞电压门控L型钙通道电流在-40 mV时被激活，在约+20 mV时达到峰值，峰值约为-120 pA，胰岛素分泌水平为(0.76±0.12)μg/L。在16.7 mmol/L葡萄糖刺激下，峰值电流电压向左移动并增加至-140 pA，测得的胰岛素分泌水平为(1.78±0.13)μg/L。分别用浓度为0.5、1.0、5.0和10.0 μmol/L的胰岛淀粉样多肽孵育胰岛β细胞。观察到在0.5 μmol/L和1.0 μmol/L组中，与对照组相比，峰值电位激活电压、电流和胰岛素分泌量均无明显变化。然而，在5.5 mmol/L葡萄糖环境中，5.0和10.0 μmol/L组的激活电压升高-30 mV，峰值电流分别降至约-80 pA和-60 pA，胰岛素分泌分别降至(0.49±0.11)μg/L和(0.36±0.12)μg/L。在16.7 mmol/L葡萄糖浓度下，激活电压从-40 mV升高至-30 mV，峰值电流分别降至-80 pA和-40 pA。同时，胰岛素分泌分别降至(1.20±0.13)μg/L和(0.89±0.14)μg/L，具有显著性差异。
在葡萄糖刺激下，胰岛素分泌与胰岛β细胞电压门控L型钙通道的开放同步。胰岛淀粉样多肽对胰岛素分泌的抑制也与胰岛β细胞电压门控L型钙通道的开放同步，且呈正浓度依赖性。
