Heitzer T, Wenzel U, Hink U, Krollner D, Skatchkov M, Stahl R A, MacHarzina R, Bräsen J H, Meinertz T, Münzel T
Medizinische Klinik II, Kardiologie and Nephrologie, Universit atskrankenhaus Eppendorf, Universität Hamburg, Hamburg, Germany.
Kidney Int. 1999 Jan;55(1):252-60. doi: 10.1046/j.1523-1755.1999.00229.x.
Angiotensin II infusion has been shown to cause hypertension and endothelial dysfunction and to increase superoxide (O-.2) production in vascular tissue, mainly via an activation of nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]-dependent oxidase, the most significant O-.2 source in endothelial and/or smooth muscle cells. With these studies, we sought to determine whether endothelial dysfunction in renovascular hypertension is secondary to an activation of these oxidases.
Endothelial function in aortas from rats with two kidney-one clip (2K-1C) hypertension and age-matched controls was assessed using isometric tension studies in organ chambers. Changes in vascular O-.2 production were measured using lucigenin-enhanced chemiluminescence and electron spin resonance spectroscopy.
In hypertensive animals, relaxation to endothelium-dependent (acetylcholine) and endothelium-independent nitrovasodilators (nitroglycerin) was impaired. Constriction to a direct activator of protein kinase C (PKC) phorbol ester 12,13 dibutyrate (PDBu) was enhanced, and vascular O-.2 was significantly increased compared with controls. Vascular O-.2 was normalized by the PKC inhibitor calphostin C, by the inhibitor of flavin-dependent oxidases, diphenylene iodonium, and recombinant heparin-binding superoxide dismutase, whereas inhibitors of the xanthine oxidase (oxypurinol), nitric oxide synthase (NG-nitro-l-arginine) and mitochondrial NADH dehydrogenase (rotenone) were ineffective. Studies of vascular homogenates demonstrated that the major source of O-.2 was a NAD(P)H-dependent oxidase. Incubation of intact tissue with PDBu markedly increased O-. 2, the increase being significantly stronger in vessels from hypertensive animals as compared with vessels from controls. Endothelial dysfunction was improved by preincubation of vascular tissue with superoxide dismutase and calphostin C.
We therefore conclude that renovascular hypertension in 2K-1C rats is associated with increased vascular O-.2 leading to impaired vasodilator responses to endogenous and exogenous nitrovasodilators. Increased vascular O-.2 is likely secondary to a PKC-mediated activation of a membrane-associated NAD(P)H-dependent oxidase.
血管紧张素II输注已被证明可导致高血压和内皮功能障碍，并增加血管组织中超氧化物（O₂⁻）的产生，主要是通过激活烟酰胺腺嘌呤二核苷酸（磷酸）[NAD(P)H]依赖性氧化酶，这是内皮细胞和/或平滑肌细胞中最重要的O₂⁻来源。通过这些研究，我们试图确定肾血管性高血压中的内皮功能障碍是否继发于这些氧化酶的激活。
使用器官腔中的等长张力研究评估两肾一夹（2K-1C）高血压大鼠和年龄匹配对照大鼠主动脉的内皮功能。使用光泽精增强化学发光和电子自旋共振光谱法测量血管O₂⁻产生的变化。
在高血压动物中，对内皮依赖性（乙酰胆碱）和内皮非依赖性硝基血管扩张剂（硝酸甘油）的舒张功能受损。对蛋白激酶C（PKC）直接激活剂佛波酯12,13-二丁酸酯（PDBu）的收缩增强，与对照相比，血管O₂⁻显著增加。血管O₂⁻通过PKC抑制剂钙泊三醇C、黄素依赖性氧化酶抑制剂二亚苯基碘鎓和重组肝素结合超氧化物歧化酶恢复正常，而黄嘌呤氧化酶（氧嘌呤醇）、一氧化氮合酶（NG-硝基-L-精氨酸）和线粒体NADH脱氢酶（鱼藤酮）的抑制剂无效。血管匀浆研究表明，O₂⁻的主要来源是NAD(P)H依赖性氧化酶。用PDBu孵育完整组织可显著增加O₂⁻，与对照血管相比，高血压动物血管中的增加明显更强。用超氧化物歧化酶和钙泊三醇C预孵育血管组织可改善内皮功能障碍。
因此，我们得出结论，2K-1C大鼠的肾血管性高血压与血管O₂⁻增加有关，导致对内源性和外源性硝基血管扩张剂的血管舒张反应受损。血管O₂⁻增加可能继发于PKC介导的膜相关NAD(P)H依赖性氧化酶的激活。
