氨基胍对糖基化蛋白损伤大鼠血管内皮功能的影响

目的　探讨糖基化终末产物形成抑制药氨基胍对外源性制备的糖基化终末产物损伤大鼠离体胸主动脉环内皮依赖性舒张功能的影响及其机制。方法　采用外源性制备的糖基化牛血清白蛋白孵育大鼠离体胸主动脉环 60min诱导血管内皮损伤 ,观察氨基胍对糖基化牛血清白蛋白所致的血管内皮依赖性舒张反应损伤是否具有保护作用。结果　外源性糖基化牛血清白蛋白明显抑制乙酰胆碱诱导的内皮依赖性血管舒张反应 ,但并不影响硝普钠诱导的内皮非依赖性血管舒张反应。用氨基胍 (50～ 50 0 μmol·L- 1 )预孵育血管环 1 5min ,再与糖基化牛血清白蛋白共同孵育 60min ,呈浓度依赖性降低糖基化终末产物对血管内皮依赖性舒张反应的抑制。此外 ,氧自由基清除剂超氧化物歧化酶 (superox idedismutase,SOD ;2× 1 0 5U·L- 1 )也能完全取消糖基化终末产物的抑制作用 ,并与 50 0 μmol·L- 1 氨基胍的保护作用相似。氨基胍 (50 0 μmol·L- 1 )亦能完全逆转SOD抑制剂二乙基二硫氨甲酸酯 (diethyldithiocarbamate,DETC ;1 0 μmol·L- 1 )诱导产生内源性氧自由基所致的血管内皮依赖性反应的损害。结论　氨基胍能取消糖基化终末产物所致大鼠离体胸主动脉环内皮依赖性舒张反应的抑制 ,氨基胍的这种保护作用可能与其抗氧化作用有关

Prevention of aminoguanidine against impairment of endothelium-dependent relaxation induced by glycosylated proteins in isolated rat aorta

AIM This study was designed to investigate the effect of aminoguanidine, an inhibitor of the glycosylated proteins formation, on the impairment of endothelium dependent relaxation induced by advanced glycation end products (AGE) in isolated rat thoracic aorta and its possible mechanisms. METHODS Exogenous glycosylated bovine serum albumin (AGE BSA) was prepared. Aortic rings were exposed to AGE BSA for 60 min to induce the impairment of endothelium dependent vasodilatation. In the drug treated groups, aortic rings were incubated with drug for 15 min and then exposed to AGE BSA for another 60 min in the presence of the drug. Vasodilator responses to acetylcholine (ACh) or sodium nitroprusside (SNP) of aortic rings were measured by isometric tension recording after drug treatment. RESULTS AGE BSA significantly inhibited the endothelium dependent relaxation in response to ACh, but did not affect endothelium independent relaxation in response to SNP. Pre incubation of aortic rings with aminoguanidine(50～500 μmol·L -1 ) for 15 min and co incubation of aortic rings with AGE BSA for another 60 min markedly attenuated the inhibition of endothelium dependenet relaxation induced by AGE BSA in a dose dependent manner. Superoxide diamutase (SOD, 2×10 5 U·L -1 ), a scavenger of superoxide anions, also prevented the inhibition of endothelium dependent relaxation, which is similar to the effect of 500 μmol·L -1 aminoguanidine. Furthermore, aminoguanidine (500 μmol·L -1 ) also reversed impairment of endothelium dependent relaxation of rat aortic ring induced by endogenous oxygen free radicals generated by diethyldithiocarbamate (DETC, 10 μmol·L -1 ) via inhibiting intracellular SOD. CONCLUSION Aminoguanidine can protect rat aortic endothelium against damage due to AGE BSA, and the beneficial effect of aminoguanidine may relate to its antioxidant properties.