Streptozotocin - 당뇨병 백서에서 당뇨병 이환기간에 따른 대동맥의 이완능 저하 및 Oxygen - Free Radical 에 의한 이완능의 손상정도 = Influences of thc Duration of Diabetes on the Impairment in the Relaxative Responses and on the Sensitivity to Oxygen - Free Radical Induced Damage in Streptozotocin - Diabetic Rat Aortas

다국어 초록 (Multilingual Abstract)

Objectives: Diabetes mellitus produces histological evidence of endothelial alterations as well as changes in vascular function in experimental animal. Oxygen free radicals interfere with or destroy endothelium-dependent relaxation in normal and diabetic blood vessels. The present study was investigated whether the duration of diabetic state can affect the severity of impairment in endothelium-dependent and/or independent relaxation and the sensitivity to oxygen free fadical (OFR)-induced damage in diabetic rat vasculature. Methods: The relaxative responses of aortic rings precontracted with norepinephrine in vitro to cumulative concentrations of acetylcholine (ACh) and nitroglycerine (NTG) were conducted in 3- and 10- week streptozotocin (STZ)-diabetic rats and agematched controls. After exposure to H2O2 generated by mixing xanthine and xanthine oxidase, the degree of impairment in relaxative responses to ACh and NTG were also compared between 3- and 10-week diabetic rats. Results: The relaxative responses of aortic rings produced by cumulative concentrations of ACh were significantly lower in both 3- and 10-week diabetic rats than in the age-matched controls. The impairments of relaxative responses to ACh in 10-week diabetic rats were significantly greater than those in 3-week ones. After H2O2 exposure, the impairments of relaxative responses to ACh in 3- and 10- week diabetic aortas was also significantly greater than those in the control ones. However, the severity of H -induced damage in 10-week diabetic aortas was not significantly different than that in 3-week ones. In contrast, aortic rings of 3- and 10-week diabetic rats could still be fully relaxed by NTG, even after exposure to H2O2. Conclusion: These findings suggest that in STZ-diabetic rat aortas selective impairment of endothelium-dependent relaxation to ACh can be found early even over a 3-week period after the induction of diabetes and the impairment may be greater in those with the longer duration of the diabetic state and that the impairment of the vascular relaxation by OFR is also selective to endothelium-dependent response but the sensitivity of OFR-induced damage may not be related to the duration of the diabetic state