Dixon Lana J, Hughes Sinead M, Rooney Keith, Madden Aine, Devine Adrian, Leahey William, Henry Welby, Johnston G Dennis, McVeigh Gary E
Department of Therapeutics and Pharmacology, The Queen's University of Belfast, Belfast, Northern Ireland.
Am J Hypertens. 2005 Jun;18(6):839-43. doi: 10.1016/j.amjhyper.2005.01.004.
Hypertension and diabetes are important independent risk factors for increased oxidative stress and increased cardiovascular risk. The combination of hypertension and diabetes results in a dramatic increase in cardiovascular risk. Enhanced oxidative stress in hypertension and diabetes is linked to decreased nitric oxide (NO) bioavailability because of its interaction with vascular superoxide (O(2)(-)), derived predominantly from NAD(P)H-dependent oxidases. When uncoupled from essential cofactors, NO synthase III (NOS III) can also produce O(2)(-). We studied platelet superoxide production in patients with hypertension alone and in patients with coexistent diabetes mellitus, investigating the contribution of NOS III uncoupling to platelet superoxide production.
Gel-filtered platelets were obtained and were stimulated with Phorbol 12-myristate 13-acetate, and O(2)(-) production was detected using lucigenin-enhanced chemiluminescence. Superoxide production was significantly higher in patients with diabetes and hypertension (6.4 +/- 1.6 pmol/min/10(8) platelets) than in patients with hypertension (1.6 +/- 0.6 pmol/min/10(8) platelets) (P < .04). After incorporation of N(omega)-nitro-l-arginine methyl ester (L-NAME, 1 mmol/L), O(2)(-) detection increased in 40% of patients with diabetes and hypertension and in 87% of patients with hypertension. This expected response results from L-NAME inhibition of NO production preventing NO scavenging of O(2)(-). A reduction in O(2)(-) production in response to L-NAME occurred in the remaining patients and indicates O(2)(*-) production by the uncoupled NOS III enzyme.
This study provides first published evidence that NOS III can reside in the uncoupled state in patients with hypertension and, to a greater extent, in patients with coexisting hypertension and diabetes, and that it contributes significantly to increased superoxide production in these disease states.
高血压和糖尿病是氧化应激增加及心血管疾病风险升高的重要独立危险因素。高血压与糖尿病并存会导致心血管疾病风险急剧增加。高血压和糖尿病中氧化应激增强与一氧化氮（NO）生物利用度降低有关，这是因为NO与主要源自NAD(P)H依赖性氧化酶的血管超氧化物（O(2)(-)）相互作用。当与必需辅因子解偶联时，一氧化氮合酶III（NOS III）也可产生O(2)(-)。我们研究了单纯高血压患者以及合并糖尿病患者的血小板超氧化物生成情况，探讨NOS III解偶联对血小板超氧化物生成的作用。
获取凝胶过滤血小板，用佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯刺激，使用光泽精增强化学发光法检测O(2)(-)生成。糖尿病合并高血压患者的超氧化物生成量（6.4±1.6 pmol/分钟/10(8)个血小板）显著高于高血压患者（1.6±0.6 pmol/分钟/10(8)个血小板）（P <.04）。加入N(ω)-硝基-L-精氨酸甲酯（L-NAME，1 mmol/L）后，40%的糖尿病合并高血压患者及87%的高血压患者的O(2)(-)检测值升高。这种预期反应源于L-NAME抑制NO生成，从而阻止NO清除O(2)(-)。其余患者中，L-NAME使O(2)(-)生成减少，这表明是解偶联的NOS III酶产生了O(2)(*-)。
本研究首次发表证据表明，NOS III在高血压患者中可处于解偶联状态，在高血压合并糖尿病患者中这种情况更为常见，并且它在这些疾病状态下超氧化物生成增加中起显著作用。
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