α-酮戊二酸通过降低胞内pH值调节大鼠血管平滑肌细胞舒张

AKG Regulates Rat Vascular Smooth Muscle Cells Relaxation by Decreasing Intracellular pH Value

【目的】血管平滑肌细胞(VSMC)是血管的基质细胞,可表达一系列舒缩相关的基因和蛋白,在血管张力维持中起重要作用。肌球蛋白轻链激酶(MLCK)激活是血管舒缩的关键信号,受胞内钙离子(Ca2+)浓度、环腺苷酸(cAMP)水平和pH值的影响。旨在探讨α-酮戊二酸(AKG)对血管平滑肌细胞舒缩的影响及其可能机制。【方法】以3周龄大鼠主动脉平滑肌细胞为模型,研究100μmol/L AKG处理1 h对细胞骨架面积和细胞内MLCK mRNA水平、钙离子浓度瞬时变化、cAMP水平、pH值的变化以及酸碱平衡相关离子转运体Na+/HCO3-共转运体(NBC)、Na+/Ca2+交换体(NCX)、Na+/H+交换体1(NHE1)、Na+/H+交换体3(NHE3)mRNA水平的影响。【结果】与对照组相比,AKG能显著扩大血管平滑肌细胞骨架面积(P<0.01),极显著上调MLCK mRNA的相对转录水平(P<0.001),极显著引起胞内钙离子瞬时浓度变化(P<0.001),但对胞内cAMP水平无显著影响(P>0.05)。进一步发现AKG能极显著降低胞内的pH值(P<0.001),且上调酸碱平衡相关离子转运体NHE3 mRNA相对转录水平(P<0.05),而NBC、NCX、NHE1 mRNA相对转录水平则无显著差异(P>0.05)。【结论】研究表明AKG可以舒张大鼠血管平滑肌细胞,其机制可能与胞内pH降低有关。研究结果为运用AKG等能量营养素代谢中间产物改善动物机体循环状态和组织血流提供理论依据。

[Objective]Vascular smooth muscle cells are stromal cells of the blood vessels,which can express a series of vasomotor genes and proteins and plays an important role in maintaining vascular tone.Activation of myosin light chain kinase(MLCK)is a key signal of vasomotor and is affected by intracellular calcium ion(Ca2+)concentration,intracellular cyclic adenosine monophosphate(cAMP)level,and intracellular pH value.This study aims to investigate the effect of α-ketoglutarate(AKG)on vascular smooth muscle cell relaxation and its possible mechanism.[Methods]3-week-old rat aortic smooth muscle cells were used as the model to study the effects of AKG treatment for 1 h on the cytoskeletal area and intracellular MLCK mRNA levels,the instantaneous changes of calcium ion concentration,the cAMP levels,pH value,and the mRNA levels of acid-base balance-related ion transporters like Na+/HCO3-cotransporters(NBC),Na+/Ca2+exchanger(NCX),Na+/H+exchanger 1(NHE1)and Na+/H+exchanger 3(NHE3.)[Result]Compared with the control group,AKG effectively dilated the cytoskeletal of vascular smooth muscle(P0.05).Furthermore,AKG dramatically decreased the intracellular pH(P<0.001),and up-regulated the relative mRNA transcription level of the acid-base balance-related ion transporter NHE3(P<0.05),while the relative mRNA transcription levels of NBC,NCX,and NHE1 had no significant differences.[Conclusion]AKG can relax rat vascular smooth muscle cells,its mechanism might be related to the decrease of intracellular pH value.This study provides experimental evidence for using AKG and other energy nutrient metabolic intermediates to improve the circulation state and tissue blood flow of animals.