维生素C对原发性高血压患者前臂血流及糖代谢的影响。

Effect of vitamin C on forearm blood flow and glucose metabolism in essential hypertension.

作者信息

Natali A, Sironi A M, Toschi E, Camastra S, Sanna G, Perissinotto A, Taddei S, Ferrannini E

机构信息

Department of Internal Medicine, University of Pisa, Pisa, Institute of Clinical Physiology, Pisa, Italy.

出版信息

Arterioscler Thromb Vasc Biol. 2000 Nov;20(11):2401-6. doi: 10.1161/01.atv.20.11.2401.

DOI:10.1161/01.atv.20.11.2401

PMID:11073844

Abstract

In 9 patients with essential hypertension, we tested whether a high-dose (12 mg. min(-1)) vitamin C infusion into the brachial artery, by improving endothelium-dependent vasodilatation, would also attenuate the insulin resistance of deep forearm tissues. We measured the effect of vitamin C on acetylcholine (Ach)-induced vasodilatation and on forearm glucose uptake during systemic hyperinsulinemia; in all studies, the contralateral forearm served as the control. Intrabrachial Ach infusion produced a stable increase in forearm blood flow, from 2.6+/-0.3 to 10.6+/-2.1 mL. min(-1). dL(-1); when vitamin C was added, a further rise in forearm blood flow (to 13.4 mL. min(-1). dL(-1); P<0.03 vs Ach alone) was observed. In response to insulin, blood flow in both the infused and control forearms did not significantly change from baseline values (+10+/-16% and +2+/-11%, respectively). In contrast, when vitamin C was added, blood flow in the infused forearm increased significantly (to 3.7+/-0.7 mL. min(-1). dL(-1); P<0.02 vs 2.8+/-0.6 mL. min(-1). dL(-1) in the control forearm). Insulin stimulated whole-body glucose disposal to 20+/-2 micromol. min(-1). kg(-1), compatible with the presence of marked insulin resistance. Forearm glucose uptake was similarly stimulated after 80 minutes of insulin infusion (to 2.11+/-0.42 and 2.06+/-0.43 micromol. min(-1). dL(-1), infused and control, respectively). When intrabrachial vitamin C was added, no difference in glucose uptake was observed between the 2 forearms (infused, 2.37+/-0.44 micromol. min(-1). dL(-1)and control, 2.36+/-0. 53 micromol. min(-1). dL(-1)). Forearm O(2) uptake at baseline was also similar in the 2 forearms (infused, 9.7+/-0.7 micromol. min(-1). dL(-1) and control, 9.6+/-1.1 micromol. min(-1). dL(-1)) and was not changed by either insulin or vitamin C. We conclude that in the deep forearm tissues of patients with essential hypertension and insulin resistance, an acute improvement in endothelial function, obtained with pharmacological doses of vitamin C, restores insulin-mediated vasodilatation but does not improve insulin-mediated glucose uptake. Thus, the endothelial dysfunction of essential hypertension is unlikely to be responsible for their metabolic insulin resistance.

摘要

在9例原发性高血压患者中，我们测试了通过向肱动脉内高剂量（12毫克·分钟⁻¹）输注维生素C来改善内皮依赖性血管舒张，是否也能减轻前臂深部组织的胰岛素抵抗。我们测量了维生素C对全身高胰岛素血症期间乙酰胆碱（Ach）诱导的血管舒张以及前臂葡萄糖摄取的影响；在所有研究中，对侧前臂作为对照。肱动脉内注入Ach可使前臂血流量稳定增加，从2.6±0.3毫升·分钟⁻¹·分升⁻¹增至10.6±2.1毫升·分钟⁻¹·分升⁻¹；加入维生素C后，观察到前臂血流量进一步增加（至13.4毫升·分钟⁻¹·分升⁻¹；与单独使用Ach相比，P<0.03）。对胰岛素的反应，注入和对照前臂的血流量与基线值相比均无显著变化（分别为+10±16%和+2±11%）。相反，加入维生素C后，注入前臂的血流量显著增加（至3.7±0.7毫升·分钟⁻¹·分升⁻¹；与对照前臂的2.8±0.6毫升·分钟⁻¹·分升⁻¹相比，P<0.02）。胰岛素刺激全身葡萄糖处置至20±2微摩尔·分钟⁻¹·千克⁻¹，这与存在明显的胰岛素抵抗相一致。胰岛素输注80分钟后，前臂葡萄糖摄取也受到类似刺激（注入侧和对照侧分别为2.11±0.42和2.06±0.43微摩尔·分钟⁻¹·分升⁻¹）。当加入肱动脉内维生素C时，两侧前臂的葡萄糖摄取无差异（注入侧为2.37±0.44微摩尔·分钟⁻¹·分升⁻¹，对照侧为2.36±0.53微摩尔·分钟⁻¹·分升⁻¹）。两侧前臂基线时的前臂氧摄取也相似（注入侧为9.7±0.7微摩尔·分钟⁻¹·分升⁻¹，对照侧为9.6±1.1微摩尔·分钟⁻¹·分升⁻¹），且不受胰岛素或维生素C的影响。我们得出结论，在原发性高血压和胰岛素抵抗患者的前臂深部组织中，通过药理剂量的维生素C实现的内皮功能急性改善可恢复胰岛素介导的血管舒张，但不能改善胰岛素介导的葡萄糖摄取。因此，原发性高血压的内皮功能障碍不太可能是其代谢性胰岛素抵抗的原因。