Oxygen-radical regulation of renal blood flow following suprarenal aortic clamping.
Oxygen-radical regulation of renal blood flow following suprarenal aortic clamping.
复制标题
肾上主动脉阻断后肾血流的氧自由基调节。
DOI：
10.1016/j.jvs.2005.10.051
复制
发表时间：
2006
影响因子：
4.3
通讯作者：
Bartula,LoriL
中科院分区：
文献类型：
--
作者：
Myers,StuartI;Wang,Li;Liu,Fang;Bartula,LoriL
目的肾功能不全仍然是影响肾上动脉瘤和肾动脉闭塞症治疗后患者的并发症。肾上主动脉阻断(肠系膜上动脉上方)和再灌流(SMA-SRACR)后肾损伤的一种机制是肾微血管血流的丧失和随后的肾功能丧失。本研究验证了SMA-SRACR后髓质和皮质微血管血流丧失的假说，这是由于氧自由基下调内源性髓质和皮质一氧化氮的合成。方法麻醉雄性SD大鼠(约350g)将微透析探头或激光多普勒纤维插入肾皮质(深度2 mm)和肾髓质(深度4 mm)。连续监测激光多普勒血流。将微透析探头连接到注射器泵上，以3μ/m in的乳酸林格液进行体内灌流。动物接受SMA-SRACR(或Sham)30分钟，然后再灌流60分钟。SMA-SRACR后30min，再灌流60min后，激光多普勒血流量与基础时间(基础)和相应的假手术组进行比较，并报告与时间零基线相比的百分比变化。在基础时间收集微透析液，并与SMA-SRACR 30min再灌注60min后收集的透析液以及相应的假手术组进行比较。分析微透析液中总一氧化氮(μM)、前列腺素E_2(PGE_2)、6-酮-前列腺素F1α(PGI_2代谢物)和血栓素B_2的合成。与基准时间零相比，数据以百分比变化的形式报告。激光多普勒血流组和微透析组分别给予生理盐水载体、N-ω-硝基-L-精氨酸甲酯盐酸盐(L-NAME)(30 mg/kg，一氧化氮合成抑制剂)、L-精氨酸(400 mg/kg，一氧化氮前体)、超氧化物歧化酶(超氧化物歧化酶，10000U/kg，氧自由基清除剂)、L-NAME+超氧化物歧化酶或L-精氨酸+超氧化物歧化酶。超氧化物歧化酶在再灌注前30min给药，其他药物在再灌注前15min给药。分离肾皮质和髓质，用免疫印迹法检测肾皮质和髓质中诱导型一氧化氮合酶(INOS)、环氧合酶-2、前列环素合成酶和前列腺素E_2合成酶的含量。结果肠系膜上动脉-SRACR导致肾髓质和髓质血流量明显减少，同时内源性髓质和皮质一氧化氮合成减少。这些变化在L治疗后进一步加重，但在SMA-SRACR后经L精氨酸治疗恢复到假手术水平。肾脏似乎通过增加皮质和髓质PGE2的合成和释放来补偿这些变化。超氧化物歧化酶治疗可恢复缺血再灌注组和L治疗组大鼠肾皮质和髓质的一氧化氮合成和血流量。结论一氧化氮在维持肾皮质和髓质的血流和一氧化氮合成中起重要作用。这些数据还支持这样的假设，即SRACR后髓质和皮质微血管血流的丧失部分是由于氧自由基下调了内源性髓质和皮质一氧化氮的合成。
OBJECTIVERenal insufficiency continues to be complication that can affect patients after treatment for suprarenal aneurysms and renal artery occlusive disease. One proposed mechanism of renal injury after suprarenal aortic clamping (above the superior mesenteric artery) and reperfusion (SMA-SRACR) is the loss of microvascular renal blood flow with subsequent loss of renal function. This study examines the hypothesis that the loss of medullary and cortical microvascular blood flow following SMA-SRACR is due to oxygen-derived free radical down-regulation of endogenous medullary and cortical nitric oxide synthesis.METHODSAnesthetized male Sprague-Dawley rats (about 350 g) either had microdialysis probes or laser Doppler fibers inserted into the renal cortex (depth of 2 mm) and into the renal medulla (depth of 4 mm). Laser Doppler blood flow was continuously monitored. The microdialysis probes were connected to a syringe pump and perfused in vivo at 3 μL/min with lactated Ringer’s solution. The animals were subjected to SMA-SRACR (or sham) for 30 minutes, followed by 60 minutes of reperfusion. Laser Doppler blood flow after the 30 minutes of SMA-SRACR followed by 60 minutes of reperfusion was compared with the time zero (basal) and with the corresponding sham group and reported as percent change compared with the time zero baseline. The microdialysis fluid was collected at time zero (basal) and compared with the dialysis fluid collected after 30 minutes of SMA-SRACR followed by 60 minutes of reperfusion as well as the corresponding sham group. The microdialysis dialysate was analyzed for total nitric oxide (μM) and prostaglandin E2(PGE2), 6-keto-PGF1α(PGI2metabolite), and thromboxane B2synthesis. The data are reported as percent change compared with the baseline time zero. The laser Doppler blood flow and microdialysis groups were treated with either saline carrier, Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) (30 mg/kg, nitric oxide synthesis inhibitor), L-arginine (400 mg/kg, nitric oxide precursor), superoxide dismutase (SOD, 10,000 U/kg, oxygen-derived free radical scavenger), L-NAME + SOD, or L-arginine + SOD. SOD was given 30 minutes before the reperfusion, and the other drugs were given 15 minutes before reperfusion. The renal cortex and medulla were separated and analyzed for inducible nitric oxide synthase (iNOS), cyclooxygenase-2, prostacyclin synthase, and PGE2synthase content by Western blot.RESULTSSuperior mesenteric artery-SRACR caused a marked decrease in medullary and cortical blood flow with a concomitant decrease in endogenous medullary and cortical nitric oxide synthesis. These changes were further accentuated by L-NAME treatment but restored toward sham levels by L-arginine treatment after SMA-SRACR. The kidney appeared to compensate for these changes by increasing cortical and medullary PGE2synthesis and release. SOD treatment restored renal cortical and medullary nitric oxide synthesis and blood flow in the ischemia-reperfusion group and in the ischemia-reperfusion group treated with L-NAME.CONCLUSIONSThese data show that nitric oxide is important in maintaining renal cortical and medullary blood flow and nitric oxide synthesis. These data also support the hypothesis that the loss of medullary and cortical microvascular blood flow following SRACR is due in part to oxygen-derived free radical downregulation of endogenous medullary and cortical nitric oxide synthesis.