Role of reactive oxygen in phospholipase A2 activation by ischemia/reperfusion of the rat kidney

Purpose. To investigate the role of phospholipase A₂ (PLA₂) in reperfusion injury of the kidney in an in vivo animal model, renal mitochondrial PLA₂ activity was measured under three different conditions. Methods. Male Wistar rats (n = 72) anesthetized with pentobarbital underwent renal ischemia surgically for 45 min and were reperfused for the indicated time (renal ischemia/reperfusion). Treatments included reperfusion for various predetermined periods (phase 1), exposure to hyperbaric oxygen (phase 2), and administration of reactive oxygen species (ROS) scavenger (phase 3). Thereafter, each kidney was harvested, and mitochondrial PLA₂ activity was measured by a radioisotope technique. Results. Ischemia/reperfusion resulted in time-related PLA₂ activation in the renal mitochondria up to 48 h of reperfusion after renal ischemia. Renal mitochondrial PLA₂ activity was further augmented by hyperbaric oxygen exposure prior to reperfusion, whereas administration of the ROS scavengers suppressed mitochondrial PLA₂ activity. Conclusion. These data suggest that ROS may play an important role in the in vivo activation of PLA₂ associated with renal ischemia/reperfusion. Received for publication on July 6, 1998; accepted on November 30, 1998     

砷对小鼠脂质过氧化和抗氧化能力的影响

采用动物实验方法,研究砷对小鼠各组织ＭＤＡ含量,ＳＯＤ活力及全血ＧＳＨ－Ｐｘ活力的影响。结果显示：心脏的中、高剂量组ＭＤＡ水平显著高于对照组和低剂量组,而ＳＯＤ活力则是中、高剂量组显著低于对照组和低剂量组;肝脏的染毒组ＭＤＡ水平均显著高于对照组,而ＳＯＤ活力低剂量组显著高于其它３组,中、高剂量组显著低于对照组和低剂量组;肾脏中仅高剂量组ＭＤＡ水平显著高于对照组,而ＳＯＤ活力各组间无显著差异。全血中的ＧＳＨ－Ｐｘ活力显著下降,并呈剂量－效应关系。表明,砷可促进机体脂质过氧化,抑制抗氧化酶（ＳＯＤ,ＧＳＨ－Ｐｘ）的活力。     

紫外线对角膜内抗氧化酶mRNA表达的影响

为了进一步从基因水平探讨紫外线的损伤机制,我们采用ＲＴ－ＰＣＲ方法,用紫外线照射大鼠角膜,检测大鼠角膜内三种抗氧化酶;谷胱甘肽过氧化物酶,铜锌－超氧化物歧化酶,过氧化氢酶ｍＲＮＡ的表达。结果显示,照射早期,三种抗氧化酶ｍＲＮＡ表达均升高,ＧＳＨ－Ｐｘ和ＳＯＤ的表达高点为照射５ｍｉｎ,ＣＡＴ的表达高点为照射２ｍｉｎ照射晚期,照射１５ｍｉｎ,三种酶的ｍＲＮＡ表达明显下降,照射后４８ｈ,三种抗氧化酶的表     

Influence of selective phosphodiesterase inhibitors on human neutrophil functions and levels of cAMP and Cai

Summary Chromatographic analysis of 3,5-cyclic nucleotide phosphodiesterase (PDE) isoenzymes in the cytosol of human neutrophils shows the predominant presence of PDE IV (cAMP specific) and PDE V (cGMP specific). PDE IV is characterized by (1) cAMP selectivity, (2) a K_M for cAMP of 1.2 M and (3) a typical rank order of IC ₅₀-values for PDE inhibitors: 0.13, 0.17, 47 and 9.5 M for PDE IV selective rolipram, PDE III/IV selective zardaverine, PDE III selective motapizone and unselective 3-isobutyl-l-methylxanthine (IBMX), respectively. Functions of polymorphonuclear leukocytes (PMN) such as N-formylmethionyl-leucyl-phenylalanine (fMLP)-stimulated superoxide release and fMLP/thimerosal elicited leukotriene (LT) biosynthesis are inhibited by these PDE inhibitors with the same rank order and even lower IC₅₀-values. Measurements of changes in cytosolic Ca_i in Fura-2 loaded PMN demonstrate a transient Ca_i increase after stimulation with 0.1 M fMLP and an additional sustained elevation of Ca_i levels in the presence of thimerosal. PDE inhibitors suppress this sustained phase of Ca_i release with the same rank order of IC₅₀-values as LT biosynthesis. The correlation between fMLP/thimerosal-induced LT biosynthesis and Ca_i levels reveal a Ca_i threshold of 150 nM for arachidonic acid metabolism. cAMP levels in PMN were elevated by PDE inhibitors alone by less than 2-fold. In the presence of fMLP however, cAMP was increased up to 10-fold and the efficacy of PDE inhibitors to increase cAMP paralleled their potency to inhibit PDE IV. It is concluded that (1) suppression of PMN functions is achieved by PDE IV inhibition, (2) necessary cAMP elevations are within 50% increase, (3) superoxide release was affected by cAMP/protein kinase A (PKA) directly whereas (4) for inhibition of LT biosynthesis a cAMP related reduction of Ca-influx is involved. Send offprint requests to Ch. Schudt at the above address     

Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats

Oxygen free radicals (OFRs) have been reported to play pivotal roles in the pathogenesis of cell damage induced by ischemia and reperfusion. The efficacy of recombinant human superoxide dismutase (rh-SOD) in the treatment of circulatory disorders after reperfusion of the splanchnic area was investigated in rats. All rats died within 3 hours after release of 60-min superior mesenteric artery occlusion (SMAO) when no treatment was given. Animals which received rh-SOD, 2mg·100g^–1BW, at reperfusion followed by a continuous infusion of rh-SOD 0.67mg·100g^–1BW·hr^–1, exhibited prolonged survival times compared with no treatment rats (231 ± 35min and 149 ± 43min, respectively). Mean blood pressure in rats treated with rh-SOD was higher than in controls after reperfusion, and was concomitant with improvement in splanchnic perfusion. The results suggest excessive activity of OFRs in reperfused organs and a possible scavenging effect of rh-SOD as a means of eliminating them.(Bitoh H: Recombinant human-type SOD attenuates circulatory disorders after reperfusion of splanchnic organs in rats. J Anesth 6: 247–254, 1992)     

针刺防治实验性动脉再狭窄模型大鼠抗氧自由基作用的初步研究

目的：探讨针刺治疗动脉再狭窄的作用机理。方法：用空气干燥法诱发大鼠颈总动脉再狭窄模型。以复方丹参注射液作对照。观察针刺对动脉再狭窄模型大鼠颈总动脉去内皮损伤的内膜增生及氧自由基的影响。结果：针刺能抑制动脉去内皮损伤的内膜增生。升高模型大鼠血清中超氧化物歧化酶（SOD）的活性。降低丙二醛（MDA）的含量。结论：针刺具有抗氧自由基的能力。逆转动脉再狭窄的病理进程，对动脉再狭窄具有较好的防治作用。     

灵芝促学习记忆及抗衰老作用实验研究

目的 :研究灵芝对血虚小鼠自发行为、学习记忆及抗衰老作用。方法 :血虚小鼠用灵芝水煎剂 ,对照组小鼠用生理盐水灌胃 ,连续 13d,期间进行小鼠开场行为和学习记忆的测定 ,以及小鼠应急力竭游泳后 2 4 h分别对小鼠脑、肝的超氧化物歧化酶 (SOD)的活性 ,脑、肝、心、脾、肌的丙二醛 (MDA)、脂褐素 (L PF)含量进行测定。结果 :灵芝对血虚小鼠开场行为中的理毛次数有显著影响 (P<0 .0 5 ) ,但对移动隔数、站立次数以及学习记忆未产生显著影响。灵芝能显著提高血虚小鼠脑、肝中的 SOD活性 (P<0 .0 5 ) ,显著降低脑、肝、心、脾、肌的 MDA、L PF的含量 (P<0 .0 5 )。结论 :灵芝可促进血虚小鼠的自发活动 ,且抗衰老作用显著     

针刺对家兔脑出血急性期超氧化物歧化酶、过氧化脂质的分时影响

目的 探讨针刺治疗脑出血机理。方法 将54只兔随机分为对照组、模型组和针刺组。采用脑内注血法造成动脉粥样硬化兔脑出血模型。选水沟、风府、曲泽、内关、三阴交、血海、太溪穴。观察针刺对急性脑出血脑组织超氧化物歧化酶(SOD)和过氧化脂质(LPO)影响。结果 模型组和针刺组SOD较对照组显著降低，并以模型组降低最为明显。脑出血后24h、72h针刺组SOD均明显高于模型组。脑出血后72h，模型组SOD较24h进一步降低；针刺组较24h明显升高。脑出血后1星期，模型组SOD较72h有所升高，但仍显著低于针刺组；针刺组SOD明显高于24h。模型组、针刺组LPO较对照组显著升高，并以模型组升高最为明显。脑出血后24h和72h，针刺组LPO均明显低于模型组。脑出血后72h，模型组、针刺组LPO较24h升高。脑出血1星期，针刺组和模型组间有极显著性差异；模型组、针刺组LPO较24h均明显降低，且明显低于72h水平。结论 在脑出血急性期，针刺可显著增强脑SOD活性，显著降低LPO含量，能稳定地增强脑出血兔抗自由基酶活性并降低脑出血后自由基脂质过氧化反应。     

Responses of antioxidant systems in the hepatocytes of common carp (Cyprinus carpio L.) to the toxicity of microcystin-LR.

The freshwater, bloom-forming cyanobacterium (blue-green alga) Microcystis aeruginosa produces a peptide hepatotoxin, which causes the damage of animal liver. Recently, toxic Microcystis blooms frequently occur in the eutrophic Dianchi Lake (300 km2 and located in the South-Western of China). Microcystin-LR from Microcystis in Dianchi was isolated and purified by high performance liquid chromatography (HPLC) and its toxicity to mouse and fish liver was studied (Li et al., 2001). In this study, six biochemical parameters (reactive oxygen species, glutathione, superoxide dismutase, catalase, glutathione peroxide and glutathione S-transferase) were determined in common carp hepatocytes when the cells were exposed to 10 microg microcystin-LR per litre. The results showed that reactive oxygen species (ROS) contents increased by more than one-time compared with the control after 6 h exposure to the toxin. In contrast, glutathione (GSH) levels in the hepatocytes exposed to microcystin-LR decreased by 47% compared with the control. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxide (GSH-Px) increased significantly after 6 h exposure to microcystin-LR, but glutathione S-transferase (GST) activity showed no difference from the control. These results suggested that the toxicity of microcystin-LR caused the increase of ROS contents and the depletion of GSH in hepatocytes exposed to the toxin and these changes led to oxidant shock in hepatocytes. Increases of SOD, CAT and GSH-Px activities revealed that these three kinds of antioxidant enzymes might play important roles in eliminating the excessive ROS. This paper also examined the possible toxicity mechanism of microcystin-LR on the fish hepatocytes and the results were similar to those with mouse hepatocytes.     

七氟醚和安氟醚对心肌缺血再灌注损伤的保护作用

目的：从细胞生化方面来探讨七氟醚和安氟醚对心肌缺血再灌注损伤的影响。方法：采用Ｌａｎｇｅｎｄｏｒｆ离体大鼠心脏模型，将３０只大鼠随机分成三组：对照组、七氟醚组和安氟醚组，每组各１０只。全心缺血３０分钟，再灌注３０分钟。结果：缺血前给予１ＭＡＣ的七氟醚或安氟醚可以明显减少再灌注冠脉流出液中乳酸脱氢酶和蛋白的释放量，降低心肌细胞内钙聚集，保护了心肌ＳＯＤ的活力。结论：七氟醚和安氟醚对缺血再灌注心肌有显著的保护作用。