Milsom A B, Jones C J H, Goodfellow J, Frenneaux M P, Peters J R, James P E
Wales Heart Research Institute, University of Wales College of Medicine, Heath Park, Cardiff, UK.
Diabetologia. 2002 Nov;45(11):1515-22. doi: 10.1007/s00125-002-0956-9. Epub 2002 Oct 12.
AIMS/HYPOTHESIS: Reduced bioavailability of endothelium-derived nitric oxide is implicated in diabetic macrovascular and microvascular disease. In patients with diabetes, we hypothesised that protein glycosylation can alter nitric oxide binding affinity of haemoglobin and plasma proteins, hence reducing nitric oxide availability and causing an alteration in nitric oxide metabolism.
Binding of nitric oxide to haemoglobin was studied across a range of glycosylation levels in vitro (HbA(1c) 5.9 to 9.8%). In clinical studies nitrate, nitrite, nitrosyl haemoglobin and plasma nitrosothiols were measured in venous blood from 23 patients with uncomplicated Type I (insulin-dependent) diabetes mellitus and 17 non-diabetic control subjects. Samples were analysed at baseline and after nitric oxide was added ex vivo.
Nitric oxide-haemoglobin binding was increased at a HbA(1c) greater than 8.5% compared with 5.9% (p<0.01). Basal nitrosyl haemoglobin was higher in diabetic patients compared with the control subjects (0.59+/-0.12 micro mol/l vs 0.24+/-0.12 micro mol/l, p<0.05). Plasma nitrosothiols, and nitrite and nitrate (NOx) concentrations were similar in diabetic patients compared with the control subjects (7.64+/-0.79 micro mol/l vs 5.93+/-0.75 micro mol/l, 13.98+/-2.44 micro mol/l vs 12.44+/-2.15 micro mol/l, respectively). In blood from diabetic patients, added nitric oxide was metabolised preferentially to nitrosyl haemoglobin and plasma nitrosothiols, with a twofold increase in nitrosyl haemoglobin observed across all concentrations of nitric oxide (p<0.05). These preferential increases correlated positively with HbA(1c).
CONCLUSION/INTERPRETATION: Nitrosyl haemoglobin is increased in patients with Type I diabetes. Preferential metabolism to nitrosyl haemoglobin and nitrosothiols occurs after increases in nitric oxide. Our results show an accentuated association between nitric oxide and glycosylated proteins, especially deoxygenated haem. An altered metabolic fate of nitric oxide could influence microvascular regulation and tissue perfusion.
目的/假设：内皮源性一氧化氮生物利用度降低与糖尿病大血管和微血管疾病有关。在糖尿病患者中，我们推测蛋白质糖基化可改变血红蛋白和血浆蛋白对一氧化氮的结合亲和力，从而降低一氧化氮的可利用性并导致一氧化氮代谢改变。
在体外一系列糖基化水平（糖化血红蛋白A1c 5.9%至9.8%）下研究一氧化氮与血红蛋白的结合。在临床研究中，测量了23例无并发症的Ⅰ型（胰岛素依赖型）糖尿病患者和17名非糖尿病对照者静脉血中的硝酸盐、亚硝酸盐、亚硝基血红蛋白和血浆亚硝基硫醇。在基线时以及离体添加一氧化氮后对样本进行分析。
与糖化血红蛋白A1c 5.9%相比，当糖化血红蛋白A1c大于8.5%时，一氧化氮与血红蛋白的结合增加（p<0.01）。糖尿病患者的基础亚硝基血红蛋白高于对照者（0.59±0.12微摩尔/升对0.24±0.12微摩尔/升，p<0.）。糖尿病患者的血浆亚硝基硫醇、亚硝酸盐和硝酸盐（NOx）浓度与对照者相似（分别为7.64±0.79微摩尔/升对5.93±0.75微摩尔/升，13.98±2.44微摩尔/升对12.44±2.15微摩尔/升）。在糖尿病患者的血液中，添加的一氧化氮优先代谢为亚硝基血红蛋白和血浆亚硝基硫醇，在所有一氧化氮浓度下亚硝基血红蛋白均增加两倍（p<0.05）。这些优先增加与糖化血红蛋白A1c呈正相关。
结论/解读：Ⅰ型糖尿病患者的亚硝基血红蛋白增加。一氧化氮增加后优先代谢为亚硝基血红蛋白和亚硝基硫醇。我们的结果显示一氧化氮与糖基化蛋白之间的关联更为明显，尤其是脱氧血红蛋白。一氧化氮代谢命运的改变可能影响微血管调节和组织灌注。
