洛伐他汀对溶血性磷脂酰胆碱引起的离体血管内皮损伤的保护作用

目的探讨洛伐他汀（Lov）对溶血性磷脂酰胆碱（LPC）所致血管内皮损伤的保护作用及机制。方法利用家兔离体胸主动脉环和培养的人内皮细胞模型,分别观察洛伐他汀对LPC致离体血管环内皮依赖性舒张反应的损伤及对内皮细胞合成NO的损伤的保护作用。血管环分别与LPC（4 mg.L-1）和洛伐他汀（0.025、0.05、0.1μmol.L-1）单独孵育和共孵各15 min,分别检测乙酰胆碱（ACh）诱导的内皮依赖性舒张（EDR）反应及硝普钠诱导的非内皮依赖性舒张（EDR）反应及血管组织中的脂质过氧化物产物丙二醛（MDA）的含量。在培养的人内皮细胞和培养基中分别加入LPC和洛伐他汀,分别检测LPC和洛伐他汀对内皮细胞中一氧化氮（NO）含量和一氧化氮合酶（eNOS）的影响。结果LPC（4 mg.L-1）与血管环孵育15 min,引起了血管EDR的显著降低,最大舒张比值较对照组明显减小（P〈0.01）,洛伐他汀剂量依赖性地减轻了LPC对血管EDR的损伤作用,其最大舒张比值较LPC损伤组明显增加,（P〈0.01）。LPC和洛伐他汀对硝普钠诱导的非内皮依赖性舒张反应无明显影响。LPC引起了血管组织中MDA浓度明显升高,与对照组相比有显著性差异（P〈0.01） 不同浓度的洛伐他汀与血管环预孵后再与LPC孵育,剂量依赖性地减少了LPC所增加的MDA浓度,与LPC损伤组比较有显著差异（P〈0.01）。LPC与培养的内皮细胞孵育,导致了内皮细胞NO含量和eNOS活性的降低,不同浓度的洛伐他汀与内皮细胞预孵后再与LPC孵育,剂量依赖性地提高eNOS活性和NO的含量。结论LPC能直接抑制血管的EDR反应,洛伐他汀能剂量依赖性地拮抗LPC对EDR反应的抑制作用。其机制可能与LPC触发脂质过氧化反应,从而抑制血管内皮细胞NO的合成和增加NO的消耗有关,洛伐他汀通过抗氧化而保护血管内皮细胞的功能。     

卡托普利抗同型半胱氨酸和溶血性磷脂酰胆碱损伤大鼠血管内皮功能

目的　研究卡托普利能否保护同型半胱氨酸(Hcy)和溶血性磷脂酰胆碱 (LPC)在体外直接损伤的大鼠离体胸主动脉内皮功能。方法　用Hcy或LPC孵育大鼠离体胸主动脉环 3 0min诱导血管内皮损伤 ,观察卡托普利对Hcy和LPC损伤血管内皮依赖性舒张反应的影响。结果　Hcy( 0 .3～ 3mmol·L-1)或LPC( 1～1 0 μmol·L-1)呈浓度依赖性地损伤乙酰胆碱诱导的内皮依赖性血管舒张反应 ,但不影响硝普钠诱导的内皮非依赖性血管舒张。卡托普利( 3～3 0 μmol·L-1)预孵育血管环 1 5min,再与Hcy( 1mmol·L-1)共同孵育 3 0min,浓度依赖性改善Hcy对血管内皮依赖性舒张反应的损害。 3 0 μmol·L-1卡托普利也可完全逆转LPC( 3 μmol·L-1)对内皮依赖性血管舒张反应的损害。结论　卡托普利对Hcy和LPC所引起的血管内皮依赖性舒张反应的损害都具有明显的保护作用     

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     

卡托普利对糖基化终产物损伤大鼠血管内皮功能的保护作用

目的研究卡托普利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。方法按文献方法制备糖基化终末产物,采用外源性糖基化终末产物（AGE-BSA）孵育大鼠离体胸主动脉环90 min诱导血管内皮功能的损伤,并观察卡托普利、超氧化物歧化酶和L-精氨酸对糖基化终末产物所致的血管内皮依赖性舒张反应损伤的影响。结果外源性糖基化终末产物孵育大鼠离体胸主动脉环90 min,明显抑制乙酰胆碱诱导的内皮依赖性血管舒张反应（endothelium-dependent relaxation,EDR）。但对硝普钠诱导的内皮非依赖性血管舒张反应没有影响。卡托普利（3、10和30μmol.L^-1）与AGE-BSA共同孵育血管环90 min,浓度依赖性地改善AGE-BSA对血管内皮依赖性舒张反应的损害。依那普利拉、氧自由基清除剂超氧化物歧化酶（superoxidedismutase,SOD,200 U.mL^-1）也可改善AGE-BSA对内皮依赖性血管舒张反应的损害,而L-精氨酸（L-argi-nine,L-Arg,3 mmol.L^-1）却没有明显的保护作用。结论卡托普利对AGE-BSA所引起的血管内皮依赖性舒张反应的损害具有明显的保护作用,该作用可能与其抗氧化作用有关,同时可能是部分巯基依赖性的。     

卡托普利对蛋氨酸所致血管内皮功能损伤的保护作用与对氧磷酶1的关系

目的探讨卡托普利对高蛋氨酸饮食所致大鼠血管内皮功能损伤的保护作用及其机制。方法将蛋氨酸通过灌胃的方法,1次.d-1,连续4周,诱导大鼠血管功能损伤,治疗组同时给予卡托普利、依那普利、N-乙酰半胱氨酸灌胃。4周后处死动物,检测血清一氧化氮(nitric oxide,NO)、丙二醛(malondialdehyde,MDA)含量、对氧磷酶(paraoxonase 1,PON1)、超氧化物歧化酶(superoxide dismutase enzyme,SOD)、血管紧张素转换酶(an-giotensin-converting enzyme,ACE)活性。取胸主动脉检测由乙酰胆碱(acetylcysteine,Ach)诱导的血管内皮依赖性舒张反应。结果高蛋氨酸损伤组大鼠血管内皮依赖性舒张反应显著减弱,血清中MDA浓度升高,PON1活性、血浆NO浓度与SOD活性降低;卡托普利、N-乙酰半胱氨酸和依那普利能显著改善血管内皮依赖性舒张反应、降低MDA浓度、提高血清中的PON1活性、SOD活性和NO浓度。结论卡托普利能够改善高蛋氨酸引起的血管内皮功能的损伤,该作用可能与保护PON1活性及其抗氧化作用、促进内皮细胞释放NO有关。     

川东獐牙菜素A保护溶血性磷脂酰胆碱诱导的内皮细胞损伤

目的 观察川东獐牙菜素A对溶血性磷脂酰胆碱(LPC)诱导的血管内皮细胞损伤的保护。方法 ①检测Cu2+诱导的低密度脂蛋白(LDL)氧化和二苯代苦味肼基自由基(DPPH)反应。②在大鼠离体胸主动脉环,检测乙酰胆碱诱导的内皮依赖性舒张反应。③培养内皮细胞,测定培养液中乳酸脱氢酶(LDH)、丙二醛(MDA)、一氧化氮(NO)和非对称性二甲基精氨酸(ADMA)浓度及细胞内二甲精氨酸二甲胺水解酶(DDAH)活性。结果①川东獐牙菜素A能显著抑制Cu2+诱导的LDL氧化和清除DPPH。②川东獐牙菜素A(10或30μmol·L-1)能改善LPC(5 mg·L-1)所致血管内皮依赖性舒张功能损伤。⑧川东獐牙菜素A(1、3或10μmol·L-1)能抑制LPC(5 mg·L-1)诱导的培养液中LDH和MDA浓度的降低以及NO浓度的增加;川东獐牙菜素A(3或10 μmol·L-1)能显著抑制LPC诱导的ADMA水平升高;川东獐牙菜素A(10μmol·L-1)能显著增加DDAH活性。结论 川东獐牙菜素A对LPC所致的血管内皮细胞损伤有保护作用,其作用与增加DDAH活性和降低AD-MA浓度有关。     

3,4,5,6-四羟基(口山)酮对高糖所致血管内皮依赖性舒张功能减退的保护作用

目的:观察3,4 ,5 ,6 - 四羟基口山酮对高糖所致血管内皮依赖性舒张功能减退的保护作用。方法:在大鼠离体胸主动脉环,用高浓度葡萄糖(2 5mmol·L-1)孵育2 4h ,检测乙酰胆碱诱导的血管内皮依赖性舒张反应;人脐静脉内皮细胞株(ECV30 4 )用高浓度葡萄糖(30mmol·L-1)培养4 8h ,测定培养液中乳酸脱氢酶(LDH)活性、一氧化氮(NO)及细胞脂质过氧化物丙二醛(MDA)含量。结果:3,4 ,5 ,6 - 四羟基口山酮(1、3和10 μmol·L-1)能显著抑制高糖所致的舒血管效应减退,并且呈剂量依赖性。3,4 ,5 ,6 - 四羟基口山酮(1、3和10 μmol·L-1)能显著抑制高糖所致的内皮细胞LDH泄漏、NO释放和MDA生成的增加。结论:3,4 ,5 ,6 - 四羟基口山酮对高糖所致的血管内皮依赖性舒张功能减退有保护作用,其保护作用与抑制脂质过氧化减少血管内皮细胞损伤有关。     

洛伐他汀对低密度脂蛋白损伤血管内皮的保护作用

目的：探讨洛伐他汀对低密度脂蛋白所致血管内皮功能损伤的保护作用及可能的机制．方法：一次性从大鼠舌下静脉注射天然低密度脂蛋白(n-LDL 4mg／kg),在舌下静脉注射n-LDL之前大鼠腹腔注射洛伐他汀(2或4mg／kg),每天一次,连续五天．注射n-LDL后48小时检测乙酰胆碱诱导的血管内皮依赖性舒张(EDR)及血清一氧化氮(N0)、丙二醛(MDA)的含量和超氧化物歧化酶(SOD)的活性．结果：一次注射n-LDL导致了EDR、血清NO水平及SOD活性明显降低,MDA的浓度明显增高。预先给予洛伐他汀能明显减轻LDL引起的EDR的抑制和血清NO水平及SOD活性的降低,减少MDA的生成,左旋硝基精氨酸(L-NNA)减弱洛伐他汀对血管内皮的保护作用．结论：洛伐他汀对LDL损伤的血管内皮具有保护作用,可能与保护内皮依赖性松弛因子和抗氧化作用有关。     

Cariporide对糖基化终末产物所致血管内皮损伤的保护作用

目的观察选择性Na /H 交换蛋白1(NHE-1)抑制剂Cariporide对外源性糖基化终末产物(AGEs)所致大鼠血管内皮功能损伤的保护作用。方法将体外制备的糖基化牛血清白蛋白(AGEs-BSA)通过尾静脉注射的方法,1次.d-1,连续4周,诱导大鼠血管功能损伤,治疗组同时给予Cariporide(0.1、1 mg.kg-1.d-1)灌胃。4周后处死动物,取胸主动脉用于血管内皮依赖性舒张功能的检测,主动脉弓做NF-κB-p65免疫组化检测,并测定血清NO及MDA含量。结果大鼠注射AGEs-BSA后,主动脉对乙酰胆碱诱导的内皮依赖性舒张反应明显降低,大鼠血清MDA水平增加,NO水平降低;Cariporide呈剂量依赖性改善AGEs-BSA所致大鼠胸主动脉内皮依赖性舒张反应降低,抑制AGEs-BSA引起的血清MDA浓度升高和血清NO的减少;给予AGEs-BSA后大鼠血管内皮NF-κB活性明显增加,Cariporide能明显抑制AGEs-BSA诱导的NF-κB活化。结论Cariporide对外源性AGEs诱导的大鼠血管内皮功能损伤具有保护作用,其保护作用可能与降低氧化应激、抑制血管内皮细胞的NF-κB活化有关。     

芝麻素对肾性高血压伴高血脂大鼠主动脉舒张功能的影响

目的:探讨芝麻素(Sesamin,Ses)改善肾性高血压伴高血脂大鼠(Rrenal hypertensive-hy-perlipidemia rat,RHHR)主动脉舒张功能损伤的作用机制.方法:RHHR灌服不同剂量Ses(100、33、10 mg·kg-1·d-1)8周后,测定主动脉环对乙酰胆碱(Acetylcholine,ACh)和硝普钠(Sodium nitroprusside,SNP)的舒张反应;测定一氧化氮合酶抑制剂左旋硝基精氨酸甲酯(N-ni-tro-L-arginine-methyl-ester,L-NAME)孵育后,动脉环对ACh的反应并计算一氧化氮(Nitric oxide,NO)活性.结果:与假手术组相比,RH-HR主动脉Ach和SNP诱导的舒张反应显著降低,NO活性减少,Ses治疗8周后能逆转上述作用.结论:Ses降压作用与改善RHHR主动脉内皮依赖性和非内皮依赖性舒张功能损伤有关.     

Effect of pravastatin on impaired endothelium-dependent relaxation induced by lysophosphatidylcholine in rat aorta

Aim: To investigate the effects of pravastatin, a potent 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on impaired endothelium-dependent relaxation induced by lysophosphatidylcholine (LPC), the major component of oxidized low-density lipoprotein, in rat thoracic aorta. Methods: Both the endothelium-dependent relaxation response to acetylcholine and the endotheliumindependent relaxation response to sodium nitroprusside of aortic rings were measured by recording isometric tension after the rings were exposed to LPC in the absence or presence of pravastatin to estimate the injury effect of LPC and the protective effect of pravastatin on the aortic endothelium, respectively. Results: Exposure of aortic rings to LPC (1-10μmol/L) for 30 min induced a significant concentration-dependent inhibition of endothelium-dependent relaxation to acetylcholine, but did not affect endothelium-independent relaxation in response to sodium nitroprusside. Pre-incubation of aortic rings with pravastatin (0.3-3mmol/L) for 15 min and then co-incubation of the rings with LPC (3 μmol/L) for another 30 min significantly attenuated the inhibition of endothelium-dependent relaxation induced by LPC. This protective effect of pravastatin (1 mmol/L) was abolished by N^G-nitro-L-arginine methyl ester (30 μmol/L), an inhibitor of nitric oxide synthase, but not by indomethacin (10 μmol/L), an inhibitor of cyclooxygenase. Moreover, protein kinase C inhibitor chelerythrine (1μmol/L) the superoxide anion scavenger superoxide dismutase (200 kU/L), and the nitric oxide precursor L-arginine (3 mmol/L) also improved the impaired endotheliumdependent relaxation induced by LPC, similar to the effects of pravastatin.C onclusion: Pravastatin can protect the endothelium against functional injury induced by LPC in rat aorta, a fact which is related to increasing nitric oxide bioavailability.     

Cocaine toxic effect on endothelium-dependent vasorelaxation: an in vitro study on rabbit aorta

Effects of cocaine on vascular endothelium relaxing properties and the related mechanism were investigated in vitro in rabbit aorta. Several vasorelaxing agents with different mechanisms, i.e. acetylcholine, substance P, calcium ionophore A23187, 2,5-di-tert-butylhydroquinone, or sodium nitroprusside, were employed. Cocaine effects on the vascular response to relaxing agents in cumulative (acetylcholine, substance P, or A23187) or single dose (2,5-di-tert-butyl-hydroquinone) were performed in endothelium-intact aortic rings precontracted with phenylephrine. Relaxing activity of cumulative doses of sodium nitroprusside was evaluated in endothelium-denuded aortic rings, in the presence of cocaine. Cocaine significantly reduced endothelium-dependent relaxations induced by acetylcholine, or substance P. By contrast A23187 endothelium-mediated relaxation as well as endothelium-independent relaxation by sodium nitroprusside were unaffected by cocaine. Furthermore, cocaine significantly increased endothelium-dependent relaxation response to 2,5-di-tert-butylhydroquinone, a sarcoplasmic Ca2+-ATPase pump inhibitor, in the aortic rings. These findings indicate that cocaine reduces nitric oxide release from vascular endothelium apparently through the inhibiting action of Ca2+-ATPase pump.     

Attenuation of endothelium-dependent relaxation in aorta from diabetic rats

Endothelium-dependent relaxation was examined in aortic ring preparations obtained from rats with streptozotocin-induced diabetes. The endothelium-dependent relaxation which was produced by acetylcholine and histamine in aortic rings precontracted with norepinephrine was significantly attenuated in aortic rings from diabetic rats when compared with the relaxation in rings from age-matched control animals. However, the relaxation induced by sodium nitroprusside (an endothelium-independent relaxant agent) in diabetic preparations was comparable to the control. These results show that diabetes leads to an impairment of the endothelium-dependent relaxation of aorta.     

Captopril restores endothelium-dependent relaxation of rat aortic rings after exposure to homocysteine

This study was designed to investigate the effects of captopril, an angiotensin-converting enzyme inhibitor, on inhibition of endothelium-dependent relaxation induced by homocysteine in isolated rat aorta. Isometric tension recordings were used to assess inhibitory effects of homocysteine and protective effects of captopril on endothelium-dependent relaxation of aortic rings. Exposure of aortic rings to homocysteine (0.3 approximately 3 mmol/L) for 30 min induced a significant concentration-dependent inhibition of endothelium-dependent relaxation response to acetylcholine (ACh), but did not affect endothelium-independent relaxation response to sodium nitroprusside. Pre-incubation of aortic rings with captopril (3 approximately 30 micromol/L) for 15 min and co-incubation of aortic rings with homocysteine (1 mmol/L) for another 30 min attenuated the inhibition of homocysteine in a dose-dependent manner. Moreover, superoxide dismutase (SOD, 200 U/mL), a scavenger of superoxide anions, reduced homocysteine-induced inhibition. L-Arginine (3 mmol/L), a precursor of nitric oxide (NO), also attenuated the impairment of vasorelaxation induced by homocysteine. However, in the combined presence of SOD and L-arginine, the inhibitory effect of homocysteine was reversed, which was very similar to the effect of 30 micromol/L captopril. These results suggest that captopril can prevent the inhibition of endothelium-dependent relaxation induced by homocysteine in isolated rat aorta, which may be related to scavenging oxygen free radicals and enhancing NO production.     

Protective effects of cariporide on endothelial dysfunction induced by high glucose

Aim: To explore the effects of cariporide, a selective sodium-hydrogen antiporter inhibitor, on endothelial dysfunction induced by high glucose. Methods: Acetylcholine (ACh)-induced endothelium-dependent relaxation (EDR), sodium nitroprusside (SNP)-induced endothelium-independent relaxation and biochemical parameters including malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO) were measured in rat isolated aorta. Results: A 6-h incubation of aortic rings with high glucose (44 mmol/L) resulted in a significant inhibition of EDR, but had no effects on endothelium-independent relaxation. After the 6-h incubation of aortic rings in the co-presence of cariporide (0.01, 0.1, and 1μmol/L) with high glucose, cariporide prevented the inhibition of EDR caused by high glucose in concentration-dependent manners. Similarly, high glucose decreased SOD activity and contents of NO, and increased MDA concentration in aortic tissue. Cariporide (1 μmol/L) significantly resisted the decrease of NO content and SOD activity, and elevation of MDA concentration caused by high glucose in aortic tissues. Mannitol (44 mmol/L) or cariporide (1μmol/L) alone had no effect on EDR, endothelium-independent relaxation and biochemical parameters. Conclusion: Cariporide significantly prevented endothelial dysfunction induced by high glucose. The mechanisms of endothelial dysfunction induced by high glucose may involve the activation of sodium-hydrogen antiporter and the generation of oxygen-free radicals, but it is not related to the change of osmolarity.     

The effects of type-1 and type-2 diabetes on endothelium-dependent relaxation in rat aorta

Diabetes mellitus is known to produce alterations in vascular reactivity. In the present study we have examined the effects of endothelium-dependent and endothelium-independent relaxing substances on thoracic aorta from insulin-dependent (Type-1) and noninsulin-dependent (Type-2) diabetic rats and their appropriate controls. Endothelium-dependent relaxations produced by acetylcholine and histamine in aortic rings precontracted with noradrenaline were significantly increased in insulin-dependent diabetic vessels. In contrast, the relaxations elicited by those agents were significantly attenuated in noninsulin-dependent diabetic aorta preparations. On the other hand, the relaxations induced by sodium nitroprusside (an endothelium-independent relaxant agent) in both types of diabetic preparations were comparable to those in control vessels. The results indicate that insulin-dependent and noninsulin-dependent diabetes lead to specific alterations of the endothelium-dependent relaxation of rat aorta.     

Investigation of the inhibitory effects of homocysteine and copper on nitric oxide-mediated relaxation of rat isolated aorta

1. Elevated plasma levels of homocysteine (HC) and copper have both been associated with the development of inflammatory vascular diseases, such as atherosclerosis. In this study, the effects of a combination of HC and copper on nitric oxide (NO)-mediated relaxation of isolated rat aortic rings were investigated. 2. Exposure to HC (10-100 microM; 30 min) had no effect on relaxation to acetylcholine (ACh; 0.01-10 microM, n=4). Pre-incubation of aortic rings with a higher concentration of HC for an extended period (1 mM; 180 min) significantly inhibited endothelium-dependent relaxation (n=4), but this inhibition was prevented by the presence of the copper chelator bathocuprione (10 microM, 180 min, n=6). 3. Exposure to HC (100 microM) and copper (10-100 microM; 30 min) caused a copper concentration-dependent inhibition of endothelium-dependent relaxation (n=4). This inhibitory effect was reduced in the presence of either superoxide dismutase (SOD; 100 u ml(-1); n=4) or catalase (100 u ml(-1); n=4), and further reduced by the presence of both enzymes (n=5). 4. HC and copper (100 microM; 30 min) significantly inhibited endothelium-independent relaxation to glyceryl trinitrate (0.01-10 microM; n=8). In contrast, HC (1 mM), alone or in combination with copper (100 microM), did not inhibit relaxation to the endothelium-independent relaxant sodium nitroprusside (0.01-10 microM; n=4). 5. These data indicate that the presence of copper greatly enhances the inhibitory actions of HC on NO-mediated relaxation of isolated aortic rings. The reduction of inhibition by catalase and SOD indicates a possible role for copper-catalyzed generation of superoxide and hydrogen peroxide leading to an increased inactivation or decreased production of endothelium-derived NO.     

Na+/Ca2+ exchanger inhibitor ameliorates impaired endothelium-dependent Na+ relaxation induced by high glucose in rat aorta

The present study was designed to investigate the effects of KB-R7943, an inhibitor of the Na+/Ca2+ exchanger, on impaired endothelium-dependent relaxation (EDR) induced by high glucose in rat isolated aorta. Both acetylcholine (ACh)-induced EDR and sodium nitroprusside (SNP)-induced endothelium-independent relaxation (EIR) were measured after aortic rings had been exposed to high glucose in the absence and presence of KB-R7943. Coincubation of aortic rings with high glucose (25 mmol/L) for 24 h resulted in a significant inhibition of EDR, but had no effect on EIR. After incubation of aortic rings in the presence of both KB-R7943 (0.1-10 micromol/L) and high glucose for 24 h, significantly attenuation of impaired EDR was observed. This protective effect of KB-R7943 (10 micromol/L) was abolished by superoxide dismutase (SOD; 200 U/mL) and l-arginine (3 mmol/L), whereas d-arginine (3 mmol/L) had no effect. Similarly, high glucose decreased SOD activity and the release of nitric oxide (NO) and increased superoxide anion (O2(-)) production in aortic tissue. KB-R7943 significantly decreased O2(-) production and increased SOD activity and NO release. These results suggest that KB-R7943 can restore impaired EDR induced by high glucose in rat isolated aorta, which may be related to the scavenging of oxygen free radicals and enhanced NO production.