Disruption of Na+,HCO3- Cotransporter NBCn1 (slc4a7) Inhibits NO-Mediated Vasorelaxation, Smooth Muscle Ca2+ Sensitivity, and Hypertension Development in Mice
Disruption of Na+,HCO3- Cotransporter NBCn1 (slc4a7) Inhibits NO-Mediated Vasorelaxation, Smooth Muscle Ca2+ Sensitivity, and Hypertension Development in Mice
复制标题
DOI：
10.1161/circulationaha.110.015974
复制
发表时间：
2011-10-25
期刊：
影响因子：
37.8
通讯作者：
Aalkjaer, Christian
中科院分区：
文献类型：
--
作者：
Boedtkjer, Ebbe;Praetorius, Jeppe;Aalkjaer, Christian
背景——pH 值的紊乱会影响动脉功能，但其机制背景仍存在争议。我们研究了 Na+、HCO3- 协同转运蛋白 NBCn1 是否通过调节细胞内 pH (pH(i)) 来影响动脉功能和血压调节。方法和结果-小鼠体内 NBCn1 的敲除消除了 Na+、HCO3- 协同转运，并通过荧光评估原位肠系膜动脉平滑肌和内皮细胞中的稳态 pHi 较低 显微镜。使用肌动描记法，NBCn1 敲除小鼠的动脉表现出乙酰胆碱诱导的 NO 介导的松弛减少，以及 rho 激酶依赖性去甲肾上腺素刺激的平滑肌 Ca2+ 敏感性降低。 NBCn1 敲除小鼠的动脉中乙酰胆碱刺激的 NO 水平（电极测量）和 N-硝基-L-精氨酸甲酯敏感的 L-精氨酸转化（放射性同位素测量）降低，而对 NO 供体 S-亚硝基-N-乙酰青霉胺、乙酰胆碱诱导的内皮 Ca2+ 反应则松弛 （荧光显微镜），总磷酸化内皮 NO 合酶表达和 Ser-1177 磷酸化内皮 NO 合酶表达（蛋白质印迹分析）不受影响。 NBCn1 敲除小鼠的动脉中 NO 介导的松弛减少并不能通过超氧化物清除来挽救。在 NBCn1 敲除小鼠的动脉中，肌球蛋白磷酸酶靶向 Thr-850 亚基的磷酸化减少。通过体外测定评估，rho激酶活性在低pH值下降低。在没有 CO2/HCO3- 的情况下，NBCn1 敲除小鼠和野生型小鼠的动脉之间没有观察到 pHi、收缩或舒张方面的差异。基于无线电遥测和尾套测量，NBCn1 敲除小鼠在静息时有轻度高血压，对 NO 合酶和 rho 激酶抑制的血压反应减弱，并且在血管紧张素 II 输注期间对高血压的发展具有抵抗力。结论 - NBCn1 敲除后平滑肌和内皮细胞的细胞内酸化抑制 NO 介导的和 孤立动脉中的 rho 激酶依赖性信号传导并扰乱血压调节。 （流通。2011；124：1819-1829。）
Background-Disturbances in pH affect artery function, but the mechanistic background remains controversial. We investigated whether Na+, HCO3- cotransporter NBCn1, by regulating intracellular pH (pH(i)), influences artery function and blood pressure regulation.Methods and Results-Knockout of NBCn1 in mice eliminated Na+, HCO3- cotransport and caused a lower steady-state pHi in mesenteric artery smooth muscle and endothelial cells in situ evaluated by fluorescence microscopy. Using myography, arteries from NBCn1 knockout mice showed reduced acetylcholine-induced NO-mediated relaxations and lower rho-kinase-dependent norepinephrine-stimulated smooth muscle Ca2+ sensitivity. Acetylcholine-stimulated NO levels (electrode measurements) and N-nitro-L-arginine methyl ester-sensitive L-arginine conversion (radioisotope measurements) were reduced in arteries from NBCn1 knockout mice, whereas relaxation to NO-donor S-nitroso-N-acetylpenicillamine, acetylcholine-induced endothelial Ca2+ responses (fluorescence microscopy), and total and Ser-1177 phosphorylated endothelial NO-synthase expression (Western blot analyses) were unaffected. Reduced NO-mediated relaxations in arteries from NBCn1 knockout mice were not rescued by superoxide scavenging. Phosphorylation of myosin phosphatase targeting subunit at Thr-850 was reduced in arteries from NBCn1 knockout mice. Evaluated by an in vitro assay, rho-kinase activity was reduced at low pH. Without CO2/HCO3-, no differences in pHi, contraction or relaxation were observed between arteries from NBCn1 knockout and wild-type mice. Based on radiotelemetry and tail-cuff measurements, NBCn1 knockout mice were mildly hypertensive at rest, displayed attenuated blood pressure responses to NO-synthase and rho-kinase inhibition and were resistant to developing hypertension during angiotensin-II infusion.Conclusions-Intracellular acidification of smooth muscle and endothelial cells after knockout of NBCn1 inhibits NO-mediated and rho-kinase-dependent signaling in isolated arteries and perturbs blood pressure regulation. (Circulation. 2011;124:1819-1829.)