Ischemia-reperfusion In Rabbits Research Articles

Ischemic postconditioning protects nonculprit coronary arteries against ischemia-reperfusion injury via downregulating miR-92a, miR-328 and miR-494.

Background: Nonculprit lesions are closely related to the prognosis of patients with ST-segment elevation myocardial infarction (STEMI). Our previous research found that ischemic postconditioning (IP) could inhibit the progression of nonculprit lesions. However, the mechanism by which IP regulates the occurrence and development of nonculprit lesions remains unclear.Methods: Firstly, a rabbit ischemia-reperfusion (IR) model was constructed. Next, the morphological characteristics of the coronary arterial tissues and myocardial tissues of the rabbits were observed using hematoxylin-eosin (H&E) staining. Then, western blot was performed to detect the expressions of AT1, Cx43, β-tubulin, Bax, Bcl-2 and cleaved caspase 3. Finally, to further confirm the effect of IP on nonculprit coronary arterial tissues, an in vitro model of oxygen and glucose deprivation/reperfusion (OGD/R) was established.Results: IR notably induced the cells apoptosis in nonculprit coronary arterial tissues and in myocardial tissues, while IR-induced cell apoptosis was significantly inhibited by IP. In addition, IP protected nonculprit coronary arterial tissues against IR via downregulating miR-92a, miR-328 and miR-494 and mRNA AT1, Cx43 and β-tubulin. Consistently, OGD/R-induced injury of Human umbilical vein endothelial cells (HUVECs) was reversed by IP.Conclusions: In this study, IP could protect nonculprit coronary arteries against IR injury via downregulating miR-92a, miR-328 and miR-494. Our findings may provide new directions for the treatment of nonculprit lesions.

Human adrenomedullin and its binding protein attenuate tissue injury and inflammation following hepatic ischemia reperfusion in rabbits

BackgroundLiver injury caused by ischemia reperfusion (I/R) during surgical procedures, such as liver resection or liver transplantation, is a major cause of liver damage and graft failure. The current method of treatment is mostly preventative (i.e., ischemic preconditioning). While a number of pharmacological modalities have been studied to reduce hepatic I/R injury, none have been entirely successful. It has been demonstrated that the administration of adrenomedullin (AM) in combination with AM-binding protein (AM/AMBP-1) exerts significant protective effects in various pathological conditions. In an effort to develop AM/AMBP-1 as a novel therapeutic for hepatic I/R injury, the present study examined the effect of a low dose of human AM, which does not induce hypotension, in combination with human AMBP-1 in a rabbit model of hepatic I/R (i.e., non-rodent species). MethodsIschemia of 70% of the liver was induced by placing a microvascular clip across the hilum of the left and median lobes for 60 min. The clip was then removed to commence reperfusion. At 15 min following clip removal (i.e., reperfusion), human AM/AMBP-1 was administered intravenously via the ear marginal vein continuously for 30 min. At 20 h, blood and tissue samples were collected for various measurements. ResultsThe serum levels of liver enzymes (alanine aminotransferase and aspartate aminotransferase) and lactate dehydrogenase, were elevated following hepatic I/R. The administration of AM/AMBP-1 significantly decreased these levels by 58, 44, 41%, respectively. Hepatic I/R increased the direct and total bilirubin levels, whereas treatment with human AM/AMBP-1 decreased these levels by 60% and 69%, respectively. Treatment with AM/AMBP-1 also inhibited interleukin-6 gene expression by 95%. There were no changes in tumor necrosis factor-α (TNF-α) gene expression and myeloperoxidase activity (MPO), lactate and Suzuki scores after treatment. The treatment, however, reduced apoptosis post-hepatic I/R in the ischemic portion of the liver. ConclusionAdditional experiments with AM and AMBP-1 alone are needed to completely interpret the experimental results in this non-rodent species of hepatic I/R injury. The present study suggests that human AM/AMBP-1 may be developed as a novel therapeutic to attenuate hepatic I/R associated inflammation and liver injury.

The Role of Melatonin in Electroacupuncture Alleviating Lung Injury Induced by Limb Ischemia-Reperfusion in Rabbits

BackgroundOur previous studies have shown that electroacupuncture (EA) can alleviate lung injury induced by limb ischemia-reperfusion, but the specific mechanism is still unclear.Material/MethodsThe animals were randomly divided into sham operation group (Sham), model group (IR), electroacupuncture group (EA), sham electroacupuncture group (SEA), and EA+luzindole group (EA+luzindole). The limb ischemia-reperfusion model was established according to previously described, the rabbits in the EA and EA+luzindole groups were given EA at ST36 and BL13 for 7 days before the model preparation and during the model implementation, however, sham EA was mainly used to stimulate the rabbits in the SEA group with shallow needling at the points 0.5 cm near ST36 and BL13. Then, 30 mg/kg of luzindole was intraperitoneally injected 30 minutes before the model preparation in the EA+luzindole group.ResultsThe wet weight/dry weight (W/D) ratio, lung injury score, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and malondialdehyde (MDA) contents in the EA group at 4 hours after reperfusion were significantly lower than those in the IR, SEA, and EA+luzindole groups. The levels of serum melatonin at T0 in the EA and EA+luzindole groups were significantly higher than those in the Sham group. The levels of serum melatonin at T1 and T2 in the IR group were significantly lower than those in the Sham group. There was no significant difference in the expression levels of melatonin receptor 1 (MR-1) and MR-2 in lung tissues among the 5 groups.ConclusionsEA could alleviate the lung injury induced by limb ischemia-reperfusion by promoting the secretion of melatonin, while having no effect on the expression of melatonin receptor in lung tissues.

Cardioprotective Effects of HSP72 Administration on Ischemia-Reperfusion Injury

BackgroundAlthough early reperfusion is the most desirable intervention after ischemic myocardial insult, it may add to damage through oxidative stress. ObjectivesThis study investigated the cardioprotective effects of a single intravenous dose of heat shock protein-72 (HSP72) coupled to a single-chain variable fragment (Fv) of monoclonal antibody 3E10 (3E10Fv) in a rabbit ischemia-reperfusion model. The Fv facilitates rapid transport of HSP72 into cells, even with intact membranes. MethodsA left coronary artery occlusion (40 min) reperfusion (3 h) model was used in 31 rabbits. Of these, 12 rabbits received the fusion protein (Fv-HSP72) intravenously. The remaining 19 control rabbits received a molar equivalent of 3E10Fv alone (n = 6), HSP72 alone (n = 6), or phosphate-buffered saline (n = 7). Serial echocardiographic examinations were performed to assess left ventricular function before and after reperfusion. Micro–single-photon emission computed tomography imaging of 99mTc-labeled annexin-V was performed with micro–computed tomography scanning to characterize apoptotic damage in vivo, followed by gamma counting of the excised myocardial specimens to quantify cell death. Histopathological characterization of the myocardial tissue and sequential cardiac troponin I measurements were also undertaken. ResultsMyocardial annexin-V uptake was 43% lower in the area at risk (p = 0.0003) in Fv-HSP72–treated rabbits compared with control animals receiving HSP72 or 3E10Fv alone. During reperfusion, troponin I release was 42% lower and the echocardiographic left ventricular ejection fraction 27% higher in the Fv-HSP72–treated group compared with control animals. Histopathological analyses confirmed penetration of 3E10Fv-containing molecules into cardiomyocytes in vivo, and treatment with Fv-HSP72 showed fewer apoptotic nuclei compared with control rabbits. ConclusionsSingle-dose administration of Fv-HSP72 fusion protein at the time of reperfusion reduced myocardial apoptosis by almost one-half and improved left ventricular functional recovery after myocardial ischemia-reperfusion injury in rabbits. It might have potential to serve as an adjunct to early reperfusion in the management of myocardial infarction.

Effect of Puerarin on Expression of Fas/FasL mRNA in Pulmonary Injury induced by Ischemia-Reperfusion in Rabbits

The effect of puerarin (Pur) on expressions of Fas/FasL mRNAs in pulmonary ischemia and reperfusion injury (PIRI) in rabbit was investigated. The sole side lung ischemia and reperfusion model was used. Rabbits were randomly divided into three groups, a sham operated group (sham, n = 10), PIR group (IR, n = 30) and PIR + Pur group (Pur, n = 30). Changes of several parameters including apoptotic index (AI), wet to dry ratio of lung tissue weight (W/D) and index of quantitative assessment of histologic lung injury (IQA) were measured after 60, 180 and 300 minutes of reperfusion. Meanwhile, the location and expression of Fas/FasL mRNA were investigated. Lung tissue was prepared for light microscopic and electron microscopic observation after 60, 180 and 300 minutes of reperfusion. Compared with group IR, Fas/FasL mRNAs were slightly expressed in intima and extima of small pulmonary artery, alveoli, and bronchiole epithelia in group Pur. The values of AI, W/D and IQA were significantly lower than those in group IR after 60, 180, and 300 minutes of reperfusion in lung tissue (P <0.01 or P <0.05). Meanwhile, the abnormal changes in lung tissue morphology were markedly less in group Pur. Puerarin notably protects lung from PIRI by inhibiting Fas/FasL mRNA expression and decreasing lung cell apoptosis in rabbits.

Effects of intraperitoneal hydrogen injection on nitric oxide synthase mRNA and malondialdehyde following limb ischemia-reperfusion in rabbits.

The purpose of this study was to investigate the effects of intraperitoneal hydrogen (H2) injection on the mRNA expression levels of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) as well as the serum malondialdehyde (MDA) level in a rabbit model of limb ischemia-reperfusion (I/R)-induced skeletal muscle injury. To establish the hind limb I/R animal model, 30 rabbits were randomly assigned to one of 3 groups: sham, I/R, and ischemia-reperfusion + H2 (IRH). An intraperitoneal injection of H2 was given to the IRH group, while an equivalent amount of air was given to the sham and I/R groups. At 3, 6, 12, and 24 h after reperfusion, serum MDA level as well as skeletal muscle iNOS and eNOS mRNA expression levels were determined. Both iNOS mRNA expression and serum MDA levels were higher in the I/R group than the sham group (p<0.01) and lower in the IRH group than the I/R group (p<0.01, p<0.05, respectively) at various time points after reperfusion. The eNOS mRNA expression level exhibited no significant difference between the I/R and sham groups after reperfusion but was significantly higher in the IRH group than in the sham group (p<0.01, p<0.05, respectively). During the I/R process, the expression of iNOS mRNA was up-regulated along with an increase in MDA. Intraperitoneal injection of H2 can down-regulate iNOS mRNA expression and up-regulate eNOS mRNA expression in the I/R process, suggesting a protective effect of H2 in I/R-induced skeletal muscle injury.

Iloprost and vitamin C attenuates acute myocardial injury induced by suprarenal aortic ischemia-reperfusion in rabbits.

The aim of this study was to evaluate antioxidant and cytoprotective effects of iloprost and Vitamin C in a distant organ after abdominal aorta ischemia-reperfusion injury. Twenty-eight New Zealand rabbits weighing 2,400-2,800 g were used for this study. The rabbits were divided into four equal groups. These groups are control group, sham group, iloprost group, and iloprost+vitamin C group. Suprarenal aorta was occluded with a vascular clamp. Following 30 minutes of ischemia, the vascular clamp was removed. Rabbits in group 3 received 10 ng/kg/min iloprost and those in group 4 received 10 ng/kg/min iloprost and 10 mg/kg vitamin C. At the end of the reperfusion period, the rabbits were sacrificed by a high intraperitoneal dose of xylazine+ketamine injection. Myocardial tissue samples were taken for electron microscopic analysis. We evaluated SOD, MDA and catalase in myocardial tissue samples. Iloprost and iloprost+vitamin C groups significantly reduced the oxidative stress markers in tissue samples (p<0.05) and significantly decreased the myofibrillar injury and mitochondrial morphology changes in the myocardial tissue as shown with electron microscopy (p<0.05). Myocardial edema was significantly alleviated by iloprost and iloprost+vitamin C administration (p<0.05). This study clearly showed that myocardial injury and edema occurred after ischemia-reperfusion of abdominal aorta and that groups administered with iloprost and iloprost+vitamin C showed an attenuation of ischemia-reperfusion injury in distant organs (Tab. 3, Fig. 4, Ref. 30).

The effect of propofol on the expression of rabbit ischemia reperfusion injury-related proteins.

To investigate the effect of propofol on the expression of rabbit ischemia-reperfusion injury-related proteins and the mechanism involved. Thirty healthy adult New Zealand rabbit were selected. After establishment of liver I/R model, the rabbits were divided into group A (sham operation group), group B (control group using saline), and group C (propofol group) with ten rabbits in each group. The total protein concentration, differentially expressed protein spots and the difference of apoptotic proteins expression levels among the three groups were compared. The total protein concentrations in group A, B, and C were 0.778, 0.835, and 0.765 μg/μl, respectively, and the protein concentration in group B was significantly higher than group A and C (p < 0.05), with no significant difference between group A and C (p > 0.05); results analyzed by PDQuest software showed that the average number of protein spots and matching ratio had no significant difference among the three groups (p > 0.05); MALDI-TOF-MS mass spectrometry identified 16 differentially expressed protein spots; the numbers of Caspase-3 positive cells in group B and C were significantly higher than those in group A, and the numbers of Bcl-2 and Bax positive cells in group B and C were significantly lower than those in group A (p < 0.05); the number of Capase-3 positive cells in group C was significantly higher than those in group B, and the number of Bcl-2 positive cells in group C was significantly lower than those in group B (p < 0.05). The numbers of Bax positive cells had no significant difference between group B and C (p > 0.05); densities of Caspase-3, Bcl-2 and Bax in group B and C were significantly higher than those in group A (p < 0.05); Western blotting results from the comparison of the number of positive cells between group B and C was in accordance to the result obtained from immunohistochemistry. After I/R injury in rabbit, there was deregulation of various proteins such as Caspase-3, Bcl-2 and Bax, which was an important factor contributing to liver injury even systematic disease. Propofol could regulate the expression of I/R injury-related proteins and inhibit the attack of free radical to liver, having a remarkable advantage in preventing I/R injury and controlling the development of I/R injury. This study provides an effective theoretical basis for the prevention and treatment of I/R injury.

Protective effect of delta opioid agonist [d-Ala2, d-Leu5] enkephalin on spinal cord ischemia reperfusion injury by regional perfusion into abdominal aorta in rabbits

[d-Ala2, d-Leu5] enkephalin (DADLE) has been reported to exhibit protective effects against hypoxic or ischemic induced brain insult. However its efficacy on the spinal cord ischemia-reperfusion injury remains unclear. Here we investigate whether DADLE could attenuate ischemia and reperfusion induced neural injury in the rabbit spinal cord. New Zealand white rabbits were subjected to spinal cord ischemia by infrarenal aortic occlusion for 30min. In the period of spinal cord ischemia, DADLE 0.5mg/kg or NS were infused continuously into the distal clamped abdominal aorta. The heart rate, blood pressure, and core temperature were monitored continuously during the whole experimental procedure. Then the neurological behavioral function was assessed with Tarlov scale system at 1h, 6h, 24h, 48h after reperfusion, and neuronal injury evaluation in the ventral horn of gray matter was measured by counting the normal motor neurons at 48h after reperfusion. Comparing with the control group, the Tarlov scores were significantly higher and the incidences of paraplegia were significantly lower in the DADLE group at four time-point recorded. In addition, the normal neurons numbers in the DADLE group were significant more than those in the control group at 48h after reperfusion. These results suggested that DADLE infused into the abdominal aorta during ischemia period could attenuate behavioral retardation and the loss of normal motor neuron induced by ischemia-reperfusion in rabbits.

Two-dimensional longitudinal strains and torsion analysis to assess the protective effects of ischemic postconditioning on myocardial function: A speckle tracking echocardiography study in rabbits

The reperfusion injury that occurs in the early reperfusion often results in myocardial dysfunction. This study evaluated global and regional left ventricular (LV) function using speckle tracking echocardiography (STE) in a rabbit ischemia–reperfusion (I/R) model with and without ischemic postconditioning (I-PostC). The aim is to investigate the potential benefit of I-PostC for myocardial function and validate whether regional longitudinal strain is an appropriate index to indicate myocardial dysfunction. Forty rabbits were divided into an ischemia–reperfusion group (group I) and an I-PostC group (group II). After the coronary arteries were ligated, LV systolic strain and twist parameters decreased, and absolute value of strain rate of isovolumetric relaxation period (SRivr) and post-systolic strain index (PSI) increased significantly in both groups (all p<0.05). After reperfusion, regional longitudinal systolic strain rate (SRsys), systolic strain (Ssys), LV twist and untwisting rate increased, and SRivr and PSI decreased in group II. These changes were not seen in group I. All STE parameters were correlated with area of necrosis (AN)/area at risk (AR) (all p<0.05). The correlations were morerelevant between SRsys and AN/AR (r=−0.673) and between Ssys and AN/AR (r=−0.777) (both p<0.001). The intra- and inter-observer repeatability of STE parameters were good with correlation coefficients (CCs) >0.8 or 0.6. The sensitivities of GSRsys, GSsys, SRsys, Ssys, and LV twist to detect the myocardial infarction were 81.3%, 62.5%, 87.5%, 93.8% and 81.3%, respectively. And the specificities of those parameters were 75.0%, 81.2%, 75.0%, 87.5% and 68.7%. These results indicate that STE is useful for quantitative detection on myocardial function improvement induced by I-PostC in a rabbit I/R model. The regional index—Ssys is an appropriate parameter to indicate myocardial dysfunction because of its sensitivity, specificity, and repeatability.

Rapid Induction of Hypothermia by the ThermoSuit System Profoundly Reduces Infarct Size and Anatomic Zone of No Reflow Following Ischemia-Reperfusion in Rabbit and Rat Hearts.

Although hypothermia reduces myocardial infarct size, noninvasive and rapid cooling methods are lacking. This study tests the effectiveness of a novel cooling apparatus on myocardial infarct size and no-reflow area in 2 models of coronary artery occlusion (CAO). Animals were randomized to normothermic (N) or hypothermic (H) groups after isolation of a proximal coronary artery. Animals were subjected to 30 minutes CAO and 3 hours reperfusion. In protocol 1 (rabbit, n = 8 per group), hypothermia was initiated, using the ThermoSuit apparatus (convective-immersion cooling), 5 minutes after the onset of CAO to a goal temperature of ∼32°C. In protocol 2 (rat, n = 5 per group), hypothermia was initiated 2 minutes after the onset of CAO to a goal temperature of ∼30°C. Goal temperature was reached in ∼20 minutes. In protocol 1, hypothermia caused an 82% reduction in infarct size as a percentage of the ischemic risk zone (N, 44% ± 5%; H; 8% ± 2%, P < 0.001) and an 89% reduction in the no-reflow area (N, 44% ± 4%; H, 5% ± 1%, P < 0.001). In protocol 2, hypothermia caused a 73% infarct size reduction (N, 51% ± 5%; H, 14% ± 6%, P < 0.01) and a 99% reduction in the no-reflow area (N, 33% ± 5%; H, 0.4% ± 0.3%, P < 0.01). The ThermoSuit device induced rapid hypothermia and limited infarct size and no reflow to the greatest extent ever observed in this laboratory with a single intervention.

Denervation of capsaicin-sensitive C fibers increases pulmonary inflammation induced by ischemia-reperfusion in rabbits

BackgroundCapsaicin-sensitive C fibers (CapsCF) are abundantly distributed in the respiratory tract. Inflammation is one of the main contributors to lung ischemia-reperfusion (IR) injury. This study was designed to investigate the role of CapsCF in lung IR-induced inflammatory response. MethodsThirty-two male rabbits were randomized into four groups as follows: sham group (S), IR group (IR), large dose of capsaicin plus sham group (CS), and large dose of capsaicin plus IR group (CIR). The CS and CIR groups were pretreated with capsaicin (100 mg/kg) to induce functional ablation of CapsCF. The IR and CIR groups were subjected to 1 h lung ischemia and 3 h reperfusion. Thereafter, blood and lung tissue samples were obtained for blood gas and biochemical analyses. Levels of substance P and calcitonin gene-related peptide (CGRP), lung wet-to-dry weight ratio, and histopathologic changes as well as neutrophil counts in bronchoalveolar lavage fluids were also assessed. ResultsCapsaicin pretreatment in the CIR group resulted in increased lung wet-to-dry ratio, neutrophil counts in bronchoalveolar lavage fluids, and lung pathologic lesions, along with higher levels of plasma tumor necrosis factor α and interleukin 8 and lower level of interleukin 10 (P < 0.05 versus IR), although capsaicin did not alter the above variables in the CS group (P > 0.05 versus S). Lung tissue CGRP was elevated more than 2-fold in the IR group (P < 0.05 versus S), but it did not significantly change in the CIR group. ConclusionDenervation of CapsCF aggravated lung IR-induced inflammation, probably by depleting the CGRP content of CapsCF. CapsCF may protect against lung IR-induced inflammation and injury.

Protective effect of intraventricle mild hypothermia on focal cerebral ischemia injury

Objective To investigate the protective effect of intraventircle mild hypothermia on focal cerebral ischemia-reperfusion in rabbits and the neuroprotective molecule mechanism.Methods The middle cerebral artery occlusion (MCAO) and reperfusion models of rabbits were achieved by thread embolism.Eighty male rabbits were randomly divided into control group,occlusion group and mild hypothermia group.The neurofunction performance of Longa score and the edema volume of the brain by Elliott method were evaluated,the cells cyle and apoptosis rate were measured by flow cytometry (FCM) and the expression level of cysteinyl aspartate-specific protease-3 (Caspase-3) protein by Western blotting.Results The neurofunctional score in the mild hypothermia group was 2.167 ± 0.753,significantly lower than that in the occlusion group (P ＜ 0.01).Dry-wet weight ratio in mild hypothermia group was 79.26 ± 1.30,which was significantly different from that in occlusion group and control group (P ＜0.01).Flow cytometry revealed that mild hypothermia significantly suppressed apoptosis rate (2.46 ± 0.84).The proportion of cells in G1 phase was declined to (64.05 ± 3.24),and that in S phase and G2 phase was increased to (43.79 ±2.25) and (12.88 ± 1.77) respectively (P ＜0.01).The hypothermia down-regulated Caspase317 kb expression (P ＜0.01).Conclusion The mild hypothermia could reduce brain edema,and inhibit apoptosis by down-regulating the Caspase-3 expression to protect the brain function. Key words: Mild hypothermia; Cerebral ischemia/reperfusion injure; Cysteinyl aspartate-specific protease-3 ; Apoptosis

Effect of Propofol on Expression of PKC mRNA in Pulmonary Injury Induced by Ischemia-Reperfusion in Rabbits

Effect of Propofol on Expression of PKC mRNA in Pulmonary Injury Induced by Ischemia-Reperfusion in Rabbits

Effect of anisodamine on lung edema after ischemia-reperfusion in rabbits

Objective To investigate the protective efficacy of anisodamine against lung edema after ischemia-reperfusion in rabbits,and to explore the possible mechanism.Methods In vivo lung ischemia-reperfusion model of rabbit was developed. Twenty-four Chinese rabbits of either gender,aged 10-12 weeks,weighing 2200-2600 g,were divided into 3 groups randomly:anisodamine group,control group and sham group,with 8 rabbits in each group.In anisodamine group,the left pulmonary hilum was occluded for 1 hour and then released for 3 hours,and anisodamine(3 mg/kg) was given by intravenously injection before occlusion. In control group,only ischemia-reperfusion was performed.In sham group,left lung received no ischemia-reperfusion.Left lung tissue in each group was harvested for histopathological analysis,lung water content determination and myeloperoxidase(MPO) level detection.Also,2%Evens blue(1.5 ml/kg) was injected into femoral venous to measure lung vascular permeability.Results After ischemia-reperfusion,the lung tissue water content,MPO level and Evens blue level in control group were(6.6±0.5) g/g dry tissue, (1.16±0.14) U/g protein and(173±16) ug/g wet tissue respectively,significantly higher than those in sham group[(4.3±0.4) g/g dry tissue,(0.53±0.09) U/g protein and(103±11)μg/g wet tissue,P0.05].These indices in anisodamine group were(5.6±0.4) g/g dry tissue,(0.82±0.11)U/g protein and(124±18)μg/g wet tissue,obviously lower than those in control group(P0.05).Left lung displayed prominent edema,septal swelling,hemorrhage and neutrophil infiltration in control group,while which was significantly improved in anisodamine group.Conclusion Anisodamine can significantly prevent lung edema after ischemia-reperfusion in rabbits. The mechanism may be ascribed to inhibition of neutrophil infiltration and decrease in vascular permeability.

Effect of controlled low perfusion pressure on expression of phosphor-Akt and phosphor-ERK following spihal ischemia-reperfusion in rabbits

Objective To investigate the effect of controlled low perfusion pressure on expression of phosphor-Akt (p-Akt) and phosphor-ERK1/2 (p-ERK1/2) following spinal ischemia-reperfusion (1/R) in rabbits.Methods Thirty-six Japanese long-ear white rabbits aged 3 months weighing 2.0-2.5 kg were randomly divided into 3 groups ( n ＝ 12 each):group sham operation (group S) ; group spinal I/R (group I/R) and group controlled low perfusion pressure (group LP).Auricular artery and femoral artery were carnulated for proximal and distal BP monitoring.A 4F catheter with a balloon at the tip was inserted into abdominal aorta.The tip was positioned 1 cm below left renal artery.Spinal ischemia was induced by inflating the balloon until the distal MAP < 20 mm Hg,and maintained for 25 min.During the first 10 min of reperfusion the distal MAP was increased to 45-55 mm Hg by partially deflating the balloon.Then the balloon was fully deflated to allow complete reperfusion.The function of lower limbs was assessed with Tarlov score (0 ＝ no detectable movement,4 ＝ normal function) at 1,3,7,28 d of reperfusion.Au the animals were sacrificed at 1 d of reperfusion in each group.The lumbar segment L3-5 of the spinal cord was removed for microscopic examination and determination of expression of p-Akt and p-ERK1/2 by immuno-histochemistry) and detection of neuronal apoptosis in dorsal horn (by TUNEL).Results Spinal I/R significantly decreased Tarlov scores,and increased the number of apoptotic cells and expression of p-Akt and pERK1/2 in group I/R as compared with group S.Low perfusion pressure during the 10 min at the beginning of reperfusion significantly increased Tarlov scores,decreased apoptotic index and further increased p-Akt and pERK1/2 expression in group LP compared with group I/R.The histopathological damage in the spinal cord was attenuated in group LP.Conclusion Controlled low pcrfusion pressure can reduce the spinal cord I/R injury by activating Akt and ERK1/2 and decreasing neuronal apoptosis. Key words: Hypotension,controlled; Protein-serine-threonine kinases; Mitogen-activated protein kinases; Reperfusion injury; Spinal cord

A single small dose of ketamine prevents lung injury following hepatic ischemia-reperfusion in rabbits

Background Previous studies demonstrated that large-dose ketamine alleviated lipopolysaccharide-induced lung injury. We investigated whether a single small dose of ketamine could attenuate lung injury induced by hepatic ischemia-reperfusion (HIR) and, if so its underlying mechanisms. Methods Thirty male New Zealand rabbits were randomized into three groups ( n = 10 each): sham group (Group S), control group (Group C), and ketamine group (Group K). In Group S, hepatic portal vein (HPV) and inferior vena cava (IVC) were left unclamped and 0.9% saline 1 mL/kg was given intravenously. In Group K, ketamine 0.5 mg/kg (0.5 mg/mL) was given intravenously 10 minutes before cross-clamping of the HPV and the IVC. In Group C, 0.9% saline was given 10 minutes before the cross-clamping. The HPV and the IVC were cross-clamped with bulldog clamps and unclamped 60 minutes later in the Group K and the Group C. Blood pressure and pulse rate were recorded throughout the procedure. Rabbits were sacrificed 6 hours postoperatively. Lung W/D ratio was calculated and expression of tumor necrosis factor-α mRNA, intracellular adhesion molecule-1 mRNA, and nuclear factor kappa B (NF-κB)/p65 were quantitatively analyzed. Accumulation of neutrophils in lung tissues was also observed. Results Small dose of ketamine alleviated the pulmonary edema, but not the systemic hypotension, induced by cross-clamping of the IVC and the HPV. Pretreatment with ketamine significantly reduced the increments of tumor necrosis factor-α mRNA, intracellular adhesion molecule-1 mRNA, and NF-κB/p65; and inhibited the aggregation of neutrophils in lung tissues following HIR. Conclusion 0.5 mg/kg ketamine pretreatment showed significant protective effect on acute lung injury induced by HIR, which might be mediated by the NF-κB pathway.

Effect of irrigation with hypothermic artificial cerebral spinal fluid on aquaporin-4 expression in spinal cord following spinal ischemia-reperfusion in rabbits

Objective To investigate the effect of irrigation with hypothermic artificial cerebral-spinal fluid (aCSF)on expression of aquaporin-4(AQP-4) in the spinal cord following spinal ischemia-reperfusion (I/R) in rabbits.Methods Fifty-four adult male New Zealand white rabbits weighing 2.0-2.5 kg were randomly divided into 3 groups (n=18 each):group sham operation(S group); group I/R and group irrigation with hypothermic aCSF (FI group). Spinal I/R was induced by clamping the abdominal aorta below renal artery for 60 min. Hypothermic aCSF(25 X.)was infused at L4,5 interspace at a rate of 30 ml/h and drained from L7,8 interspace during spinal ischemia.Neurological function was evaluated at 4, 24, 48 and 72 h of reperfusion and scored (0=no hind limb activity, 4=hind limb function completely recovered) in 6 animals in each group. Six animals were sacrificed at 4, 24 and 72 h respectively in each group.The lumbar segment (L5-8) was removed for measurement of water content and AQP-4 protein expression (by immuno-histochemistry).Results Neurological function scores were significantly lower,water content was higher and AQP-4 expression smaller in group I/R than in group S. I/R-induced effects were significantly attenuated by irrigation of hypothermic aCSF. Conclusion Irrigation with hypothermic aCSF can ameliorate the spinal cord I/R injuries by up-regulation of AQP-4 expression. Key words: Hypothermia, induced; Cerebrospinal fluid; Reperfusion injury; Spinal cord; Aqua-porin 4

Effect of isoflurane delayed preconditioning on the expression of Bcl-2 and caspase-3 in myocardium during ischemia reperfusion in rabbits

To investigate the effect of isoflurane delayed preconditioning on the activation of caspase-3 and the expression of Bcl-2 in rabbit myocardium during ischemia reperfusion and the possible mechanism. Forty New Zealand male white rabbits were randomly divided into 4 groups: a sham group (Group C), an I/R group, an isoflurane group (Group S), and an isoflurane + opioid recepters inhibitor group (Group N). Group S was exposed to 2.0% isoflurane for 2 h. Group N was given naloxone (6.0 mg/kg) before exposing to 2.0% isoflurane. Group C and Group I/R were exposed for 2 h to 100% oxygen, serving as untreated controls. Twenty-four hours later, Group S and Group N underwent 40 min of coronary occlusion followed by 2 h of reperfusion. At the end of the reperfusion, infarct size(IS) and area at risk(AAR) were defined by Evans and TTC staining. The myocardial ultrastructure was observed by electron microscopy. The levels of the myocardial Bcl-2 and caspase-3 expression were determined by Western blot. The caspase-3 activity of Group S was significantly lower than that of Group I/R(P<0.05). The IS was significantly reduced in Group S(19.7%+/-2.8%) as compared with Group I/R(37.8%+/-1.7%) (P<0.05). Microscopic examination showed less myocardial damage in Group S than in Group I/R. Isoflurane delayed preconditioning can inhibit the apoptosis of myocardium by up-regulating the expression of Bcl-2 and down-regulating the activation of caspase-3, which may be part of the molecular mechanism of isoflurane delayed preconditioning on myocardial preservation.

Role of L-Arginine, a Substrate of Nitric Oxide Biosynthesis, on Intestinal Ischemia-Reperfusion in Rabbits

To study whether treatment with L-arginine (ARG), a substrate of nitric oxide biosynthesis, attenuates intestinal dysfunction caused by ischemia (I) and reperfusion (R), rabbits treated with ARG (100 mg · kg −1, intravenously) or saline solution (SS) prior to I (60 minutes) by occlusion of superior mesenteric artery and/or during R (120 minutes). After I or I/R, 2-cm jejunal segments were isolated and mounted in an organ bath to study of neurogenic contractions stimulated by electrical pulses or KCl using a digital recording system. Thin jejunal slices were stained (hematoxylin and eosin) for analysis by optical microscopy. Compared to the sham group, jejunal contractions were similar in I + ARG, but reduced in I + SS, I/R + SS, and I/R + ARG groups. The jejunal enteric nerves were damaged in I + SS, I/R + SS, and I/R + ARG, but not in I + ARG group, suggesting that ARG can attenuate intestinal dysfunctions due to I, but not to R.