Calò Lorenzo A, Pagnin Elisa, Davis Paul A, Sartori Michelangelo, Semplicini Andrea
Department of Clinical and Experimental Medicine, Clinica Medica 4, University of Padova, Italy.
Nephrol Dial Transplant. 2003 Aug;18(8):1518-25. doi: 10.1093/ndt/gfg204.
Bartter's and Gitelman's syndromes (BS/GS) have a blunted Gq protein-mediated cell signalling despite high circulating angiotensin II (Ang II) levels. This is associated with reduced Galphaq gene expression, intracellular inositol trisphosphate and Ca(++) release, PKC activity and cell reactivity. Ang II is a powerful stimulator of vascular oxidases but BS/GS patients show reduced total volatile LDL oxidation products and reduced LDL susceptibility to oxidation suggesting low level of oxidative stress. Therefore, we evaluated oxidative stress-related proteins in plasma and monocytes of patients with BS/GS, at baseline and after Ang II stimulation.
In two BS and seven GS patients, biochemically and genetically characterized, and in 10 age- and sex-matched control subjects, we measured total plasma antioxidant power (AOP), plasma peroxynitrite level and gene expression of the NADH/NADPH oxidase subunit p22(phox), TGFbeta and haeme oxygenase-1 (HO-1) in circulating monocytes in basal condition and after stimulation with Ang II. Furthermore, we investigated the C(242)T polymorphism of p22(phox), whose topography in a potential haeme-binding site suggests a role in the regulation of oxidative stress.
AOP was higher in BS/GS patients than in controls (3.27 +/- 0.95 mmol/l vs 1.05 +/- 0.16, P = 0.002), together with higher plasma renin activity and aldosterone level (9.88 +/- 4.64 vs 0.95 +/- 0.08 nmol Ang I/h/ml, P < 0.0001; and 0.73 +/- 0.13 vs 0.18 +/- 0.01 nmol/l, P < 0.0001, respectively). The plasma peroxynitrite level was undetectable both in patients and controls. mRNA expression of p22(phox) and TGFbeta was reduced in BS/GS patients compared to controls [0.35 +/- 0.08 vs 0.53+/-0.05 densitometric units (d.u.), P = 0.005, and 0.82 +/- 0.07 vs 1.15 +/- 0.25 d.u., P = 0.006, respectively]. HO-1 mRNA was increased in BS/GS patients in comparison to controls (0.88 +/- 0.07 vs 0.78 +/- 0.11 d.u., P = 0.037). After acute Ang II exposure, p22(phox), TGFbeta and HO-1 gene expression significantly increased only in controls (from 0.59 +/- 0.12 to 0.96 +/- 0.11, P < 0.001, from 0.97 +/- 0.1 to 1.27 +/- 0.22, P < 0.008, and from 0.62 +/- 0.1 to 0.82 +/- 0.09, P < 0.001, respectively). Finally, C(242)T polymorphism of p22(phox) was undetectable.
The intracellular responses to Ang II mediated by reactive oxygen species are reduced in BS/GS patients. This may contribute to their vascular hyporeactivity.
巴特综合征和吉特曼综合征（BS/GS）患者尽管循环血管紧张素II（Ang II）水平较高，但Gq蛋白介导的细胞信号传导减弱。这与Gαq基因表达降低、细胞内三磷酸肌醇和Ca(++)释放减少、蛋白激酶C活性及细胞反应性降低有关。Ang II是血管氧化酶的强大刺激剂，但BS/GS患者的总挥发性低密度脂蛋白氧化产物减少，且低密度脂蛋白对氧化的敏感性降低，提示氧化应激水平较低。因此，我们评估了BS/GS患者血浆和单核细胞中氧化应激相关蛋白在基线及Ang II刺激后的情况。
在两名经生化和基因特征鉴定的BS患者、七名GS患者以及10名年龄和性别匹配的对照受试者中，我们测量了基础状态及Ang II刺激后循环单核细胞中血浆总抗氧化能力（AOP）、血浆过氧亚硝酸盐水平以及NADH/NADPH氧化酶亚基p22(phox)、转化生长因子β（TGFβ）和血红素加氧酶-1（HO-1）的基因表达。此外，我们研究了p22(phox)的C(242)T多态性，其在潜在血红素结合位点的拓扑结构提示其在氧化应激调节中发挥作用。
BS/GS患者的AOP高于对照组（3.27±0.95 mmol/l对1.05±0.16，P = 0.002），同时血浆肾素活性和醛固酮水平也较高（分别为9.88±4.64对0.95±0.08 nmol Ang I/h/ml，P < 0.0001；以及0.73±0.13对0.18±0.01 nmol/l，P < 0.0001）。患者和对照组的血浆过氧亚硝酸盐水平均未检测到。与对照组相比，BS/GS患者中p22(phox)和TGFβ的mRNA表达降低[分别为0.35±0.08对0.53±0.05光密度单位（d.u.），P = 0.005；以及0.82±0.07对1.15±0.25 d.u.，P = 0.006]。与对照组相比，BS/GS患者的HO-1 mRNA增加（0.88±0.07对0.78±0.11 d.u.，P = 0.037）。急性暴露于Ang II后，仅对照组中p22(phox)、TGFβ和HO-1基因表达显著增加（分别从0.59±0.12增至0.96±0.11，P < 0.001；从0.97±0.1增至1.27±0.22，P < 0.008；从0.62±0.1增至0.82±0.09，P < 0.001）。最后，未检测到p22(phox)的C(242)T多态性。
BS/GS患者中由活性氧介导的对Ang II的细胞内反应减弱。这可能导致其血管反应性降低。
