糖尿病患者内皮tPA、NO储备与血管舒张功能变化

目的　探讨糖尿病患者血管舒张功能和内皮组织纤溶酶原激活物 (tPA)、一氧化氮 (NO)储备释放功能与糖尿病性血管病变的关系。方法　对 15名正常人和 2 3例 2型糖尿病患者 ,采用高频超声方法测定血流介导和硝酸甘油介导的血管舒张功能和颈总动脉内膜厚度 ,以及采用静脉闭塞试验测定tPA和NO储备释放。结果　与正常对照组比较 ,糖尿病组的非内皮依赖性血管舒张功能无显著变化 ,而内皮依赖性血管舒张功能和tPA、NO释放明显低下 (P <0 .0 5或P <0 .0 1) ,颈总动脉内膜增厚 ,但差异无显著性。正常组血tPA水平与NO水平 ,以及tPA释放与NO释放呈显著正相关 ,而糖尿病组收缩压、舒张压均与内皮依赖性血管舒张功能和非内皮依赖性血管舒张功能呈显著负相关。结论　糖尿病患者存在明显的内皮tPA、NO储备释放功能和内皮依赖性舒张功能障碍 ,此与糖尿病性血管病变密切相关

The reserve of tissue plasminogen activator and nitric oxide in endothelium and its relation to vasodilation in diabetic patients

Objective To study the changes in the endothelial reserve capacity to release tissue plasminogen activator (tPA) and nitric oxide (NO) and its relation to vasodilation and to diabetic angiopathy. Methods The capacity of vascular endothelium to release tPA and NO was examined by venous occlusion of the upper arm. Brachial artery diameter was measured at baseline, during postocclusion reactive hyperemia (flow-mediated endothelium-dependent), and after sublingual nitroglycerol administration (endothelium-independent), using a high resolution ultrasound technique in 15 control subjects and 23 patients with type 2 diabetes mellitus. Vasodilation was expressed as the percentage change relative to the baseline diameter, while endothelial tPA and NO release was expressed as the percentage change relative to the baseline tPA and NO levels. Thickness of the intima of carotid artery was measured using ultrasound imaging. Results There was no significant difference in endothelium-independent vasodilation between control subjects and diabetics. However, significant reductions in endothelium-dependent vasodilation (P<0.05), endothelial NO release and tPA release (P<0.05 and P<0.01 respectively) were found in diabetics compared with those in control subjects, although no difference in intima-medial thickness of the carotid artery in these two groups. There were significant positive correlations between tPA level and NO level at baseline and between tPA release and NO release in control subjects. In addition to significant negative correlations between blood pressures, both systolic and diastolic, and endothelium-dependent, as well as endothelium-independent vasodilations in patients with diabetes mellitus. Conclusion There are significantly impaired endothelium-dependent vasodilation and endothelial tPA and NO release in patients with diabetes mellitus. The impaired functions are closely related to diabetic angiopathy.