Keegan A, Walbank H, Cotter M A, Cameron N E
Department of Biomedical Sciences, University of Aberdeen, Scotland.
Diabetologia. 1995 Dec;38(12):1475-8. doi: 10.1007/BF00400609.
We examined the effect in rats of 2 months of streptozotocin-induced diabetes mellitus on relaxation and contraction of aortas in vitro. A further diabetic group was treated from time of diabetes induction with a 1% dietary supplement of vitamin E. Diabetes caused a 26.5% deficit (p < 0.001) in maximum endothelium-dependent relaxation to acetylcholine in phenylephrine-precontracted aortas. This was 64.3% attenuated (p < 0.01) by vitamin E treatment; maximum relaxation was not significantly altered compared to non-diabetic rats. Vitamin E treatment of non-diabetic rats did not significantly affect acetylcholine-induced relaxation. Diabetes or treatment did not significantly alter acetylcholine sensitivity. Endothelium-independent relaxation response to glyceryl trinitrate was not affected by diabetes or vitamin E treatment, indicating that vascular smooth muscle responses to nitric oxide remained unaltered. There was a 35.4% reduction in the maximum contractile response to phenylephrine with diabetes (p < 0.05) which was unaffected by vitamin E treatment. The data suggest that the chronic deficit in nitric oxide-mediated endothelium-dependent relaxation in diabetes depends largely upon excess activity of reactive oxygen species. Treatment with vitamin E to increase free radical scavenging specifically protected vascular endothelium although it had no effect on deficits in vascular smooth muscle contractile responses.
我们研究了链脲佐菌素诱导的糖尿病大鼠2个月对离体主动脉舒张和收缩的影响。另一组糖尿病大鼠从诱导糖尿病时起接受1%维生素E膳食补充剂治疗。糖尿病导致苯肾上腺素预收缩主动脉对乙酰胆碱的最大内皮依赖性舒张出现26.5%的缺陷（p<0.001）。维生素E治疗使这种缺陷减轻了64.3%（p<0.01）；与非糖尿病大鼠相比，最大舒张没有显著改变。对非糖尿病大鼠进行维生素E治疗对乙酰胆碱诱导的舒张没有显著影响。糖尿病或治疗对乙酰胆碱敏感性没有显著改变。对硝酸甘油的非内皮依赖性舒张反应不受糖尿病或维生素E治疗的影响，表明血管平滑肌对一氧化氮的反应保持不变。糖尿病时对苯肾上腺素的最大收缩反应降低了35.4%（p<0.05），维生素E治疗对此没有影响。数据表明，糖尿病中一氧化氮介导的内皮依赖性舒张的慢性缺陷很大程度上取决于活性氧的过度活性。用维生素E治疗以增加自由基清除，特别保护了血管内皮，尽管它对血管平滑肌收缩反应的缺陷没有影响。
