Ubiquitin and endogenous antioxidant enzymes participate in neuroprotection of the rabbit spinal cord after ischemia and bradykinin postconditioning

The aim of this study was to investigate neuroprotective effect of bradykinin postconditioning on the rabbit spinal cord after 20 min of ischemia and 3 days of reperfusion. Bradykinin was administered by single i.p. application at 1, 6, 12 or 24 h after ischemia. Assessment of neurological function of hind limbs (Tarlov score) was estimated. Quantitative analysis was evaluated by Fluoro Jade B method, NeuN and ubiquitin immunohistochemistry in anterior horn neurons of the spinal cord. Histomorphologically distribution of ubiquitin and endogenous antioxidant enzymes (SOD1, SOD2, catalase) immunoreaction was described. Bradykinin postconditioning showed decreased number of degenerated neurons, increased number of surviving neurons and increase in number of ubiquitin positive neurons in all bradykinin postconditioned groups versus ischemia/reperfusion group. According to our results bradykinin postconditioning applied 24 h after ischemia significantly decreased (p < 0.001) number of degenerated neurons versus ischemia/reperfusion group. The least effective time window for bradykinin postconditioning was at 12 h after ischemia. Tarlov score was significantly improved (p < 0.05) in groups with bradykinin postconditioning applied 1, 6 or 24 h after ischemia versus ischemia/reperfusion group. Tarlov score in group with bradykinin application 12 h after ischemia was significantly decreased (p < 0.05) versus sham control group. Neuronal immunoreaction of ubiquitin, SOD1, SOD2 and catalase influenced by bradykinin postconditioning was dependent on neuronal survival or degeneration. In conclusion, bradykinin postconditioning showed protective effect on neurons in anterior horns of the rabbit spinal cord and improved motor function of hind limbs.     

Bradykinin preconditioning induces protective effects on the spinal cord ischemic injury of rats

The study was performed to investigate the effects of bradykinin preconditioning on spinal cord ischemic injury using an in vivo transient spinal cord ischemia model in rats. Prior to ischemia, bradykinin was infused continuously via the left femoral artery starting 15min before ischemia. Neurological functions were evaluated for 7 days postoperatively using modified Tarlov's scores. Tarlov's score outcomes showed a marked improvement in the bradykinin group compared to the ischemia group. The blood-spinal cord barrier (BSCB) permeability was also decreased by bradykinin preconditioning after 72 h reperfusion focal spinal cord in rats, which was greatly reversed by B9430 (bradykinin B2 receptor antagonist). Immunohistochemical and Western blot analysis of spinal cords revealed a significant increase in basic fibroblast growth factor protein (bFGF) levels. The study demonstrated that bradykinin preconditioning induces protection against spinal cord ischemic injury, and this protection is likely due to the protection of the vasculature of the spinal cord and the promotion of neuronal survival.     

大鼠心脏硫酸腺嘌呤预处理心肌酶活性变化

目的实验观察经典缺血处理及硫酸腺嘌呤处理大鼠心肌细胞色素氧化酶和过氧化氢酶的活性变化.方法采用SD雄性大鼠24只,分4组假手术组、缺血再灌注组、经典缺血预处理组、硫酸腺嘌呤预处理组.术后速取左心室前壁肌行冰冻切片,以DAB法测定细胞色素氧化酶和过氧化氢酶的活性.依Ridit法行显著性检验.结果缺血再灌注组大鼠心肌过氧化氢酶和细胞色素氧化酶损伤性反应明显,经典缺血预处理组和硫酸腺嘌呤预处理组细胞色素氧化酶、过氧化氢酶损伤性反应较之明显减轻(P＜0.05).结论经典缺血预处理和硫酸腺嘌呤预处理对缺血再灌注大鼠心肌损伤有明显保护作用.     

缺血预处理快速效应对兔急性缺血脊髓的保护作用

目的:探讨缺血预处理快速相对兔腹主动脉短暂阻断致缺血脊髓的保护作用。方法:36只雄性新西兰兔随机分成3组(n=12):即缺血再灌注损伤组(IR组)、缺血预处理组(IPC+IR组)及假手术组(Sham组)。IR组阻闭兔腹主动脉肾下段20min,复制兔脊髓缺血损伤模型;IPC+IR组预先阻闭腹主动脉肾下段6min,再灌注30min后再次阻闭腹主动脉肾下段20min;Sham组除不夹闭腹主动脉外,其余处理同IR组。再灌注后8h、12h、24h和48h分别对动物神经功能评分,然后,处死动物取脊髓(L_5-7),分别行组织病理学观察及测定脊髓组织中Na⁺,K⁺-ATP酶的活性。结果:Sham组及IPC+IR组神经功能评分各时点均明显高于IR组(P＜0.01);Sham组及IPC+IR组脊髓前角正常神经细胞数明显多于IR组(P＜0.01);Sham组及IPC+IR组脊髓组织中Na⁺,K⁺-ATP酶的活性明显高于IR组(P＜0.01)。结论:缺血预处理快速相对兔急性缺血脊髓有显著的保护作用,这种保护作用可能与稳定Na⁺,K⁺-ATP酶的活性有关。     

脊髓缺血性再灌注损伤和预处理保护作用的实验研究

目的：探讨缺血预处理对家兔须缺血性损伤的保护作用。方法：家兔18只，随机分为Ⅰ组（假手术组）、Ⅱ组（缺血预处理组）和Ⅲ组（缺血再灌组），每组6只，Ⅰ组开腹后，在左肾动脉起点以下0．5cm处暴露并分离腹主动脉即关腹；Ⅲ组一次性阻断腹主动脉血流30min，松夹后关腹；Ⅱ组阻断腹主动脉血流5min，松夹后再灌注10min（如此反复2次），最后再持续夹闭腹主动脉30min，松夹后关腹。结果：Ⅰ组术后后肢运动功能全部正常，光镜和电镜检查显示组织结构变化甚微。Ⅲ组术后后肢运动功能发生严重障碍，脊髓组织严重损伤，与Ⅲ组比较，Ⅱ组术后后肢运动功能障碍较轻微，须组织损伤明显减轻，神经功能评价各组差异具有显著性（P12h=0.006和P36h=0.001)。结论：缺血预处理能够促进神经功能的恢复，减轻脊髓组织损伤，提示预处理对脊因再灌注损伤具有保护作用。     

Protective effects of melatonin against spinal cord injury induced oxidative damage in rat kidney: A morphological and biochemical study

Spinal cord injury (SCI) induced oxidative stress affects multiple organ systems including the kidney. We studied the possible protective effects of melatonin on SCI-induced oxidative damage in renal tissues of rats. Wistar albino rats (n = 24) were exposed to SCI and divided into vehicle- or melatonin-treated SCI groups. Melatonin was administred intraperitoneally at a dose of 10 mg/kg for seven days. Renal tissues were investigated by light and electron microscopy. Furthermore, tissue malondialdehyde (MDA) and glutathione (GSH) levels and myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were also determined. In the vehicle-treated SCI group, the renal histology was disturbed compared to controls, whereas the melatonin-treated SCI group showed significantly reduced degeneration of renal tissue as seen by both light and electron microscopy. MDA levels, MPO and SOD activities were increased and GSH levels were decreased in the vehicle-treated SCI group compared to controls. On the other hand, decreased MDA levels and MPO activities and increased GSH levels were observed in the melatonin-treated SCI group compared to vehicle-treated SCI group. These results showed that experimentally induced SCI caused oxidative stress in the rat kidney, whereas melatonin treatment reduced oxidative stress, suggesting that it may be used as a complementary therapy of renal problems occurring following SCI.     

Ischemic preconditioning suppresses apoptosis of rabbit spinal neurocytes by inhibiting ASK1-14-3-3 dissociation

The mechanism by which a brief episode of sublethal ischemia followed by reperfusion (ischemic preconditioning, IPC) prevents the lethal effects of subsequent periods of prolonged ischemia, are poorly understood. A completely randomized, controlled study was designed to study the effect of IPC using a rabbit model of ischemic spinal cord injury. Twenty-four white adult New England rabbits were randomly assigned to one of 3 groups (n=8 per group); the groups were assigned as follows: Group I: sham-operation group, Group II: ischemic reperfusion (I/R) group, and Group III: ischemic preconditioning group. Spinal cord ischemia was induced by introducing an infra renal aortic cross-clamp for 30min. Following injury, rabbits were subjected to 30min, 2h, or 8h of reperfusion in Group II. In Group III, subjects underwent three cycles, 5min each, of ischemia followed by 5min of reperfusion, before receiving 30min of ischemia. We previously reported that the association between ASK1 (apoptosis signal-regulating kinase 1) and 14-3-3 played an important role in regulating ischemia/reperfusion spinal cord injuries. To evaluate the effect of ischemic preconditioning in injured spinal cords, we examined alterations in spinal tissue morphology, activation of key members of the ASK1-mediated signaling pathway, and the association between ASK1 and 14-3-3. Changes in spinal cord morphology were observed with hematoxylin and eosin (H&E) staining and electron microscopy. The phosphorylation levels of ASK1, JNK, and p38 were assessed by immunoblot analysis. The association between ASK1 and 14-3-3 was analyzed by co-immunoprecipitation experiments. We observed that swelling of the neurocyte bodies and hemorrhage of the spinal cord were dramatically decreased in Group III compared to Group II. In addition, the degree of apoptosis among neurocytes was reduced in Group III compared to Group II. Finally, the phosphorylation of ASK1, JNK, p38 and the dissociation of ASK1 from 14-3-3 were dramatically decreased in Group III compared with Group II. These results indicate that ischemic preconditioning may have a protective affect against ASK1/14-3-3 dissociation-induced spinal cord injuries.     

Oxidative stress induced by intermittent exposure at a simulated altitude of 4000 m decreases mitochondrial superoxide dismutase content in soleus muscle of rats

The effects were examined of 6-month intermittent hypobaric (4000 m) exposure on the antioxidant enzyme systems in soleus and tibialis muscles of rats. At the end of the 6-month experimental exposure, the six rats in both the exposed group and the control group were sacrificed. Immunoreactive mitochondrial superoxide dismutase (Mn-SOD) contents were measured as well as the activities of antioxidant enzymes [Mn-SOD, cytosolic SOD (Cu,Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX)]. Thiobarbituric acid-reactive substances (TBARS) were also determined as an indicator of lipid peroxidation. The high altitude exposure resulted in a marked increase in TBARS content in soleus muscle, suggesting increased levels of oxygen free radicals. Conversely, significant decreases in both Mn-SOD content and activity in solens muscle were oted affer exposure. Such trends were not noticed in tibialis muscle. On the other hand, no significant changes in Cu,Zn-SOD, CAT, or GPX were observed in either muscle. These results suggested that the increases in lipid peroxidation were most probably a result of decreased Mn-SOD function which was more depressed in oxidative than in glycolytic muscle.     

A model of ischemia and reperfusion increases JNK activity,inhibits the association of BAD and 14-3-3, and induces apoptosis of rabbit spinal neurocytes

It is now well established that the protein BAD (a pro-apoptotic Bcl-2 family protein) plays a pivotal role in determining cell death and survival. The c-Jun N-terminal kinase (JNK) pathway has been hypothesized to be involved in regulation of BAD. To clarify the role of BAD within the JNK pathway, a randomized, controlled study was designed using a rabbit model of ischemic spinal cord injury 5 and 8. Forty-five white adult New England rabbits were randomly assigned to one of the three groups: sham-operation group (n = 5), vehicle group (n = 20), and JNK inhibitor group (n = 20). We examined alterations in spinal tissue morphology, local concentration and cellular locations of key regulatory proteins, and protein–protein interactions. Changes in spinal cord morphology were observed with hematoxylin and eosin (H&E) staining and electron microscopy. In the vehicle group, the amount of JNK phosphorylation, cytochrome c release, and the interaction between BAD and Bcl-XL or Bcl-2 were increased compared with the JNK inhibitor group. Similarly, the phosphorylation of BAD (Ser136) and the interaction between BAD and 14-3-3 were decreased in the vehicle group. Immunohistochemical studies showed that cytoplasmic location of 14-3-3 and p-BAD (Ser136) were decreased in the vehicle group compared with the JNK inhibitor group. In addition, mitochondrial morphology was better preserved and the percentage of apoptosis was lower when JNK was inhibited. These results indicate that the JNK pathway has a critical role in the survival of neurocytes by regulating the interaction between BAD and 14-3-3.     

Oxidative stress determined through the levels of antioxidant enzymes and the effect of N-acetylcysteine in aluminum phosphide poisoning

Introduction:

The primary objective of this study was to determine the serum level of antioxidant enzymes and to correlate them with outcome in patients of aluminum phosphide (ALP) poisoning and, secondly, to evaluate the effect of N-acetylcysteine (NAC) given along with supportive treatment of ALP poisoning.

Design:

We conducted a cohort study in patients of ALP poisoning hospitalized at a tertiary care center of North India. The treatment group and control group were enrolled during the study period of 1 year from May 2011 to April 2012.

Interventions:

Oxidative stress was evaluated in each subject by estimating the serum levels of the enzymes, viz. catalase, superoxide dismutase (SOD) and glutathione reductase (GR). The treatment group comprised of patients who were given NAC in addition to supportive treatment (magnesium sulfate and vasopressors, if required), while in the control group, only supportive treatment was instituted. The primary endpoint of the study was the survival of the patients.

Measurements and Results:

The baseline catalase (P = 0.008) and SOD (P < 0.01) levels were higher among survivors than non-survivors. Of the total patients in the study, 31 (67.4%) expired and 15 (32.6%) survived. Among those who expired, the mean duration of survival was 2.92 ± 0.40 days in the test group and 1.82 ± 0.33 days in the control group (P = 0.043).

Conclusions:

This study suggests that the baseline level of catalase and SOD have reduced in ALP poisoning, but baseline GR level has not suppressed but is rather increasing with due time, and more so in the treatment group. NAC along with supportive treatment may have improved survival in ALP poisoning.     

缺血预处理对肺再灌注损伤脂质过氧化的影响

目的：观察缺血预处理对在体兔肺常温缺血再灌注损伤脂质过氧化的影响。方法：采用阻断左肺门的肺缺血再灌注损伤模型。硫代巴比妥酸法及UFN13直接法测肺组织丙二醛（MDA）、超氧化物歧化酶（SOD）、谷航甘肽过氧化物酶（GSHpx)及肺组织光镜观察。结果：缺血再灌组左肺MDA较假手术组和缺血组为高,而SOD和GSHpx活性较低（P＜0．01）,肺组织损伤较重。与缺血再灌组比较,缺血预处理 缺血再灌组有较低的MDA含量和较高的SOD与GSHpx活性（P＜0．05）,肺损伤亦较轻。结论：缺血预处理可减轻兔肺常温缺血再灌注诱导的脂质过氧化反应。     

Preconditioning of the response to ischemia/ reperfusion-induced plasma leakage in hamster cheek pouch microcirculation

OBJECTIVE:

Ischemic preconditioning and some drugs can protect tissues from injury by preserving microcirculation. This study evaluated vascular permeability in a hamster cheek pouch preparation using either short ischemic periods or bradykinin as preconditioning stimuli followed by 30 min of ischemia/reperfusion.

METHOD:

Sixty-six male hamsters were divided into 11 groups: five combinations of different ischemic frequencies and durations (one, three or five shorts periods of ischemia, separated by one or five minutes) with 10 min intervals between the ischemic periods, followed by 30 min ischemia/reperfusion; three or five 1 min ischemic periods with 10 min intervals between them followed by the topical application of histamine (2 µM); bradykinin (400 nM) followed by 30 min of ischemia/reperfusion; and three control groups (30 min of ischemia/reperfusion or histamine or bradykinin by themselves). Macromolecular permeability was assessed by injection of fluorescein-labeled dextran (FITC-dextran, MW = 150 kDa; 250 mg/Kg body weight), and the number of leaks/cm2 was counted using an intravital microscope and fluorescent light in the cheek pouch.

RESULTS:

Plasma leakage (number of leaks/cm²) was significantly reduced by preconditioning with three and five 1 min ischemic periods, one and three 5 min ischemic periods and by bradykinin. Histamine-induced macromolecular permeability was also reduced after three periods of 5 min of ischemia.

CONCLUSION:

Short ischemic periods and bradykinin can function as preconditioning stimuli of the ischemia/reperfusion response in the hamster cheek pouch microcirculation. Short ischemic periods also reduced histamine-induced macromolecular permeability.     

Matrix metalloproteinase-9 (MMP-9) expression and extracellular signal-regulated kinase 1 and 2 (ERK1/2) activation in exercise-reduced neuronal apoptosis after stroke

Exercise preconditioning has been shown to reduce neuronal damage in ischemic/reperfusion (I/R) injury. ERK1/2 signaling in injury has been thought to modulate neuroprotection. In this study, we investigated the effects of ERK1/2 activation on the expression and activity of MMP-9 and downstream neuronal apoptosis. Adult male Sprague–Dawley rats were subjected to 30 min of exercise on a treadmill for 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Apoptotic protein caspase-3 and neuronal apoptosis in cortex and striatum was determined by Western blot at 24 h reperfusion and TUNEL staining at 48 h reperfusion in 5 I/R injury groups: no treatment, MMP-9 inhibitor (doxycycline), pre-ischemic exercise, exercised animals undergone ERK1/2 inhibition (U0126), and dual inhibition of ERK1/2 and MMP-9 in exercised ischemic rats. Cerebral MMP-9 expression in ischemic rats with different treatment was determined at 6, 12 and 24 h reperfusion by real-time PCR for mRNA, Western blot for protein and zymography for enzyme activity. Exercise preconditioning significantly (p < 0.05) reduced apoptosis determined by caspase-3 and TUNEL. In non-exercised rats, doxycycline treatment had significant (p < 0.05) reductions in apoptosis after I/R injury. The dual ERK1/2–MMP-9 inhibited exercised animals had significantly (p < 0.05) reduced neuronal apoptosis that was similar to that seen in exercised ischemic rats. MMP-9 expression in I/R injury was significantly (p < 0.05) reduced in the exercised animals as compared to non-exercised controls. When ERK1/2 was inhibited, the reduced MMP-9 expression was reversed to the level seen in the non-exercised controls. This study has suggested that exercise-induced neuroprotection in I/R injury may be mediated by MMP-9 and ERK1/2 expression, leading to a reduction in neuronal apoptosis.     

NFκB在大鼠局灶性脑缺血预处理抗细胞凋亡中作用的研究

目的：研究NFκB在大鼠局灶性脑缺血预处理抗细胞凋亡中作用。方法： 采用开颅方法阻断大鼠大脑中动脉（MCAO），通过脑梗塞体积分析及病理形态学变化，观察脑缺血预处理的保护作用。采用TUNEL的方法检测神经细胞的凋亡程度。免疫组化染色和细胞化学方法检测脑组织核转录因子NFκB p65蛋白的表达和超氧歧化酶 (SOD)活性、丙二醛（MDA）水平的变化。结果： 预处理未引起脑组织神经元的病理性损伤，相对于未经预处理的缺血组，经预处理的脑缺血组脑组织梗塞体积显著减小，半影区凋亡细胞数明显减少，且细胞核NFκB p65蛋白表达显著增加，脑组织SOD的活性亦明显增大，MDA值明显减小(均P<0.01)。结论： 缺血预处理能够减轻再次的缺血性损伤所诱导的神经细胞凋亡。NF-κB可能是缺血预处理保护中抗凋亡信号调节的关键步骤之一。     

The protective roles of mitochondrial ATP-sensitive potassium channels during hypoxia–ischemia–reperfusion in brain

The role of ATP-sensitive potassium (K_ATP) channels in cerebral ischemia–reperfusion has been well documented. K_ATP channel openers protect neuron by mimicking ischemic preconditioning. However, the different protection between the mitochondrial and sarcolemma K_ATP openers has been seldom studied. In the experiment, we investigated the effects of K_ATP channel openers diazoxide and pinacidil on the hypoxia–ischemia–reperfusion in cultured hippocampal neurons and gerbil brain. The cultured hippocampal neurons and gerbil brain were pretreated with diazoxide or pinacidil before oxygen-glucose deprivation (OGD) and cerebral ischemia–reperfusion, respectively. Survival rate, apoptosis rate and lactate dehydrogenase (LDH) releasing after the reperfusion were subsequently detected. Then the subunits mRNA was detected by RT-PCR. The survival rate and LDH content in diazoxide group increased more than that in pinacidil group (86.21 ± 2.73% vs. 78.59 ± 1.94%, P < 0.05; 133.29 ± 15.00 U/L vs. 193.47 ± 3.39 U/L, P < 0.01). The apoptosis rate in diazoxide group decreased significantly more than that in pinacidil group (23.82 ± 0.14% vs. 37.05 ± 0.67%, P < 0.01). Diazoxide pretreatment increased the expression of Kir6.1 mRNA obviously. The results suggested that mitoK_ATP channels opener diazoxide played a major protective role on cerebral ischemia–reperfusion. Furthermore, diazoxide might become a new treatment for cerebral ischemia diseases through increasing the expression of Kir6.1 mRNA.     

缺血预处理对大鼠缺血性脑损伤线粒体钙、细胞色素C水平的影响

目的：观察缺血预处理对大鼠缺血性脑损伤后线粒体钙、细胞色素C水平的影响。 方法： 用大鼠右侧大脑中动脉阻闭制成局灶性脑缺血模型。24只大鼠，每组8只，随机分为缺血预处理组、 模型组和假手术组。缺血预处理组于3 d前给予30 min预缺血及72 h再灌注，实验时行2 h缺血4 h再灌注。用张均田的改良方法测定细胞色素C含量。用火焰原子吸收法检测线粒体钙含量。 结果： 缺血预处理组动物的细胞色素C、线粒体钙与假手术组相比差异显著（P<0.05,P<0.01）, 缺血预处理组与模型组相比差异显著（P<0.05,P<0.01）。 结论： 缺血预处理减少线粒体释放细胞色素C,维持线粒体钙稳态。     

Recombinant human erythropoietin prevents motor neuron apoptosis in a rat model of cervical sub-acute spinal cord compression

The objective of the study was to investigate the effects of recombinant human erythropoietin (rhEPO) in a rat model of cervical sub-acute spinal cord compression. 80 Wistar rats were randomly divided into 4 groups. Rats in the sham group (Group A, n = 5) underwent surgical procedures without cervical spinal cord compression; while rats in other groups were subjected to the spinal compression process. In the control group (Group B, n = 25), rats received an i.v. injection of 1 mL saline at day 7 post-surgery. Rats in the low-dose group (Group C, n = 25) and the high-dose group (Group D, n = 25) were treated with rhEPO at 500 units/kg body-weight and 5000 units/kg, respectively, via intravenous injection at day 7 post surgery. Limb motor function was scored by Basso–Beattie–Bresnahan (BBB) standards at 3, 7, 14, 21 and 28 days post-surgery. The distribution and quantities of EPO and its receptor (EPO-R) in the compressed segment of the spinal cord were detected by immunohistochemistry. Motor neuron apoptosis in the spinal cord was evaluated using TUNEL staining and flow cytometry at the indicated time points. Finally, IL-8, TNF-α, IL-6, and IL-1β levels in the compressed cervical spinal cord were determined by ELISA within the lesion epicenter at each time point post-surgery. The data suggest that expression of EPO-R was significantly increased following sub-acute cervical spinal cord compression; Groups C and D exhibited better BBB scores at all observed time points compared with the control group (p < 0.01). Using TUNEL staining and FCM, we observed that rhEPO profoundly inhibited motor neuron apoptosis in the spinal cord at day 21 (p < 0.01). Additionally, treatment with rhEPO halted the elevation of inflammatory cytokines. rhEPO administration decreased motor neuron apoptosis in the cervical spinal cord, improved motor functions and reduced the inflammatory response in a sub-acute cervical spinal cord compression model. Moreover, sustained treatment with low doses of rhEPO revealed a positive therapeutic effect.     

Isoflurane preconditioning protects motor neurons from spinal cord ischemia: its dose-response effects and activation of mitochondrial adenosine triphosphate-dependent potassium channel

We examined in a rabbit model of transient spinal cord ischemia (SCI) whether isoflurane (Iso) preconditioning induces ischemic tolerance to SCI in a dose-response manner, and whether this effect is dependent on mitochondrial adenosine triphosphate-dependent potassium (K(ATP)) channel. Eighty-six rabbits were randomly assigned to 10 groups: Control group (n=8) received no pretreatment. Ischemic preconditioning (IPC) group (n=8) received 5 min of IPC 30 min before SCI. The Iso 1, Iso 2 and Iso 3 groups (n=10, 9, 8) underwent 30 min of 1.05, 2.1 and 3.15% Iso inhalation commencing 45 min before SCI. The Iso 1HD, Iso 2HD and Iso 3HD groups (n=9, 9, 8) each received a specific mitochondrial K(ATP) channel blocker, 5-hydroxydecanoic acid (5HD, 20mg/kg), 5 min before each respective Iso inhalation. The 5HD group (n=8) received 5HD without Iso inhalation. The sham group (n=9) had no SCI. SCI was produced by infra-renal aortic occlusion via the inflated balloon of a Swan-Ganz catheter for 20 min. The Iso 1, Iso 2 and Iso 3 groups showed a better neurologic outcome and more viable motor nerve cells (VMNCs) in the anterior spinal cord 72 h after reperfusion than the control group (p<0.05). Iso 3 group showed a better neurologic outcome and more VMNCs than Iso 1 group (p<0.05). And, the Iso 1, Iso 2 and Iso 3 groups showed a better neurologic outcome and higher VMNC numbers than the corresponding Iso 1HD, Iso 2HD and Iso 3HD groups (p<0.05). This study demonstrates that Iso preconditioning protects the spinal cord against neuronal damage due to SCI in a dose-response manner via the activation of mitochondrial K(ATP) channels.