NS309 恢复 2 型糖尿病 ZDF 大鼠肠系膜小动脉中的 EDHF 型松弛。
NS309 restores EDHF-type relaxation in mesenteric small arteries from type 2 diabetic ZDF rats.
机构信息
The Water and Salt Research Center, Institute of Physiology and Biophysics, Aarhus University, DK-8000 Aarhus C, Denmark.
出版信息
Br J Pharmacol. 2010 Jan;159(1):154-65. doi: 10.1111/j.1476-5381.2009.00525.x. Epub 2009 Dec 10.
BACKGROUND AND PURPOSE
The endothelium-derived hyperpolarizing factor (EDHF)-type relaxation in mesenteric small arteries from 21 week old Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats was investigated using (6,7-dichloro-1H-indole-2,3-dione 3-oxime) (NS309), a potent activator of small-conductance, calcium-activated potassium channel (SK(Ca)) and intermediate-conductance, calcium-activated potassium channel (IK(Ca)).
EXPERIMENTAL APPROACH
In the presence of inhibitors of cyclooxygenase and nitric oxide synthase [indomethacin and N(omega)-nitro-L-arginine methyl ester (l-NAME), respectively], acetylcholine (ACh)-induced hyperpolarization and EDHF-type relaxation were investigated under isometric conditions in the wire myograph using 0.5 and 1 microM NS309 and/or selective blockers of SK(Ca) and IK(Ca) channels. Membrane potential was recorded with glass microelectrodes, and changes in the intracellular calcium concentration of endothelial cells were visualized by confocal microscopy. SK(Ca) expression was assessed by Western blotting.
KEY RESULTS
In arteries from ZDF rats, ACh-induced relaxation and membrane hyperpolarization were attenuated and, compared with arteries from ZL rats, NS309 was less potent at causing relaxation. Incubation with 0.5 microM NS309 did not increase ACh-induced relaxation in arteries from ZDF rats significantly. However, 1 microM NS309 restored it (both in the absence and in the presence of indomethacin and l-NAME) without changing endothelial intracellular calcium concentration. The restored EDHF-type relaxation was more sensitive to TRAM-34 (1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole) (1 microM) than to apamin. Expression of the SK(Ca) channel was unaltered.
CONCLUSIONS AND IMPLICATIONS
The attenuated EDHF-type relaxation in mesenteric small arteries from ZDF rats can be restored by NS309 without changes in the intracellular calcium concentration of endothelial cells. These results may have clinical implications for the treatment of endothelial dysfunction in overweight type 2 diabetic patients.
背景与目的
本研究旨在使用（6,7-二氯-1H-吲哚-2,3-二酮 3-肟）（NS309），一种强效的小电导钙激活钾通道（SK(Ca)）和中电导钙激活钾通道（IK(Ca)）激活剂，研究 21 周龄 Zucker 瘦（ZL）和 Zucker 糖尿病肥胖（ZDF）大鼠肠系膜小动脉的内皮衍生超极化因子（EDHF）型松弛。
实验方法
在环氧化酶和一氧化氮合酶抑制剂（分别为吲哚美辛和 N(omega)-硝基-L-精氨酸甲酯（l-NAME））存在下，使用 0.5 和 1 μM NS309 和/或 SK(Ca)和 IK(Ca)通道选择性阻滞剂，在等长条件下，在有线肌描记器中研究乙酰胆碱（ACh）诱导的超极化和 EDHF 型松弛。使用玻璃微电极记录膜电位，并通过共聚焦显微镜可视化内皮细胞内钙离子浓度的变化。通过 Western 印迹评估 SK(Ca)表达。
主要结果
与 ZL 大鼠的动脉相比，ZDF 大鼠的 ACh 诱导的松弛和膜超极化减弱，并且与 ZL 大鼠的动脉相比，NS309 引起松弛的作用较弱。在 ZDF 大鼠的动脉中，0.5 μM NS309 孵育并没有显著增加 ACh 诱导的松弛。然而，1 μM NS309 在没有改变内皮细胞内钙离子浓度的情况下恢复了它（无论是在没有吲哚美辛和 l-NAME 的情况下，还是在有吲哚美辛和 l-NAME 的情况下）。恢复的 EDHF 型松弛对 TRAM-34（1-[(2-氯苯基)二苯甲基]-1H-吡唑）（1 μM）更敏感，而对 apamin 不敏感。SK(Ca)通道的表达没有改变。
结论与意义
ZDF 大鼠肠系膜小动脉中减弱的 EDHF 型松弛可以通过 NS309 恢复，而内皮细胞内钙离子浓度没有变化。这些结果可能对超重 2 型糖尿病患者内皮功能障碍的治疗具有临床意义。
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