Effects of non-wounded ischemic preconditioning on ischemia-reperfusion injury in isolated rat hearts

AIM:To observe the protective effect of non-wounded ischemic preconditioning on ischemic/reperfusion injury in isolated rat hearts. METHODS: 25 male SD rats, weighting (250±30) g, were randomly divided into three groups: control group (C,n=8), anoxia/reoxygenation group (A,n=8) and non-wounded legs ischemic preconditioning group (N-WIP,n=9).Hearts were isolated from rats and perfused on a Langendorff apparatus with a normal Krebs-Henseleit buffer (saturation 95% O₂+5% CO₂) at a constant pressure (8.33 kPa) and temperature (37 ℃) in C group; Following 15 min equilibration, hearts were subjected to 15 min of global ischemia and 15 min reperfusion (37℃) in A group; Rats were subjected to non-wounded leg repeated-brief ischemic preconditioning, and then treated in procedure similar to A group in N-WIP group.The activities of superoxide dismutase (SOD) and Ca²⁺-Mg²⁺-ATPase, malondialdehyde (MDA) content of efflux from coronary vessel and myocardium, myocardium monophasic action potential and contractile force were measured before ischemia, 15 minutes after ischemia and 5, 15 minutes after reperfusion. RESULTS:Compared with A group, non-wounded legs ischemic preconditioning reduced the incidence of reperfusion arrhythmias (P＜0.05), decreased the content of MDA of myocardium (P＜0.01), enhanced the activities of SOD (P＜0.01) and stabilized myocardial membranous potential,the activity of Ca²⁺-Mg²⁺-ATPase and contractile function. CONCLUSION:These results indicate that non-wounded leg ischemic preconditioning has a protective effect on ischemia-reperfusion injury in isolated rat hearts. The mechanism may be related to the strength of antioxidation, the stability of Ca²⁺-Mg²⁺-ATPase activity and membranous structure in myocardium.     

Effects of ligustrazine ferulate on myocardial apoptosis and apoptosis-related protein expression in rats with myocardial ischemia-reperfusion injury

AIM:To observe the effects of ligustrazine ferulate on the apoptosis of myocardial cells in rats with myocardial ischemia-reperfusion injury, and to explore its possible mechanism. METHODS:Sixty male SD rats were randomly divided into five groups: sham-operation group, ischemia-reperfusion group, ligustrazine (4 mg/kg) group, low-dose (4 mg/kg) ligustrazine ferulate group and high-dose (8 mg/kg) ligustrazine ferulate group. The rat myocardial ischemia-reperfusion model was established by 30 min of myocardial ischemia followed by 120 min of reperfusion. Drugs were administered to the rats by jugular vein injection 10 min before reperfusion. After the reperfusion was finished, the biochemical indicators in serum and the histological indexes in myocardium were detected. RESULTS: Compared with ischemia-reperfusion group, ligustrazine ferulate lowered the serum levels of creatine kinase MB form, lactate dehydrogenase, cardiac troponin I and malondialdehyde, elevated the activity of total superoxide dismutase in serum and the expression of Bcl-2 protein in myocardium, decreased the expression of Bax protein and myocardial apoptotic index, and increased the Bcl-2/Bax ratio (all P<0.01). All the indicators in ligustrazine ferulate groups were dose-dependently superior to those in ligustrazine group (P<0.05 or P<0.01). CONCLUSION: Ligustrazine ferulate protects rats against myocardial ischemia-reperfusion injury. Its anti-apoptotic effect may be related to up-regulation of Bcl-2 and down-regulation of Bax.     

Liver X receptors attenuate myocardial ischemia-reperfusion injury through modulating GLUT-4

AIM：To investigate whether liver X receptors (LXRs) attenuate myocardial ischemia-reperfusion (I/R) injury in isolated rat heart through modulating glucose transporter 4 (GLUT-4). METHODS：Isolated rat hearts were used to establish the model of ischemia-reperfusion injury using Langendorff apparatus. The hearts were divided into 7 groups: LXR agonist T0901317 (0.1, 0.5 and 10 μmol/L) pretreatment groups, ischemic preconditioning group, control group, control+DMSO group, and I/R group. The releases of lactate dehydrogenase (LDH) and creatine kinase (CK), the infarct size, the hemodynamic parameters (left ventricle developed pressure,left ventricle end-diastolic pressure, coronary flow and ±dp/dt max), the relative mRNA level of GLUT-4 and the protein content of GLUT-4 in the myocardial cell membrane were compared between these groups. RESULTS：Besides producing hemodynamic disorders, I/R increased the activities of LDH and CK, and the infarct size in model groups. Treatment with T0901317 significantly suppressed ischemia-reperfusion injury-induced increases in LDH and CK, and reduced the infarct size. T0901317 also significantly ameliorated the parameters of haemodynamics. Treatment with T0901317 significantly increased GLUT-4 expression at mRNA and protein levels in the myocardial cell membrane. CONCLUSION：Liver X receptors may attenuate myocardial ischemia-reperfusion injury in isolated rat heart by modulating the expression of GLUT-4.     

Effect of DADLE on lung injury in rats with acute global cerebral ischemia-reperfusion

AIM：To observe the effects of δ opioid receptor agonist DADLE on acute lung injury (ALI) induced by acute global cerebral ischemia-reperfusion in rats. METHODS：SD rats (n=30) were randomly divided into sham group, model (I/R) group and DADLE treatment group. Global cerebral ischemia-reperfusion model was established by a modified 2-vessel occlusion plus hypotension. DADLE (5 mg/kg) treatment was performed via the left jugular injection before reperfusion. After 120-min reperfusion, the pathological changes of the lung tissues were observed under light microscope and electronic microscope. The activity of superoxide dismutase (SOD) and malondialdehyde (MDA) level were detected. The partial pressure of arterial oxygen (PaO2) was also measured. RESULTS：In I/R group, widened alveolar septum, capillary dilatation and congestion, endovascular and perivascular cells in the lung with neutrophil infiltration, and significantly reduced type II epithelial cell surface microvilli, alveolar lumen cavity and trachea with serous exudate were observed. SOD activity decreased, but the MDA level increased. Compared with I/R group, the SOD activity increased and MDA level decreased in DADLE treatment group, with significantly reduced lung congestion, the degree of lung injury, and the infiltration of neutrophils. Compared with I/R group, the PaO2 and oxygenation index in DADLE treatment group were increased. CONCLUSION：Various degrees of pulmonary injury were observed in acute global cerebral ischemia reperfusion model. DADLE might have a protective effect on lung tissues of ALI in rats.     

Effects of ischemic preconditioning on hepatocyte apoptosis induced by hepatic ischemia-reperfusion in cirrhotic rats

AIM:To investigate the protective effect of ischemic preconditioning (IPC) on hepatic ischemia-reperfusion(I/R) injury in cirrhotic rats and its possible mechanism. METHODS:Hepatic I/R was induced by Pringle maneuver. The cirrhotic rats were randomized into three groups: Group A: before 30 min of ischemia, a short period of 5 min ischemia and 5 min reperfusion were given; Group B: before 30 min of ischemia, a short period of 10 min ischemia and 10 min of reperfusion were given; Group C: 30 min ischemia only. The serum alanine transferase (ALT), hepatic Fas-mRNA, caspase-3 activity and hepatocyte apoptosis were analyzed. RESULTS:The 7-day survival rate in the group A and B were 100%, respectively. However, it was only 62.5% in the group C. After 6 h of reperfusion, the ALT levels in both group A and B were significantly lower than that of in group C, P＜0.01. The ALT level of group A was also lower than that of group B, P＜0.01. The hepatic Fas-mRNA expression, caspase-3 activity and apoptotic hepatocyte in group A were significantly lower than those of in group C, P＜0.01. CONCLUSIONS:IPC has significant protective effect against hepatic I/R injury. An IPC with 5 min of ischemia and 5 min of reperfusion has the maximal protective effect. The protective mechanism of IPC against hepatic I/R injury is via down-regulation of Fas-mRNA expression, inhibiting caspase-3 activity and subsequently inhibiting hepatocyte apoptosis.     

Protective effect of ischemic preconditioning on rat brain with ischemia/reperfusion injury

AIM:To study whether ischemic preconditioning(IPC) has a protective effect against ischemia/reperfusion(I/R) injury in brain, and the possible relationship between IPC and the regulating function of microcirculation.METHODS:The I/R models were established both in I/R and IPC groups of Sprague-Dawley rats. Additional procedure was performed of short term cerebral ischemic preconditioning in IPC group 24 hours before I/R. Skull windows were performed through which microcirculation features were measured before ischemia, during ischemia, and reperfusion. Finally, brains were cut into slices and stained with red tetrazoline(TTC).RESULTS:Most TTC stained brains in I/R group presented irregular palely red areas which were few in IPC group. Compared with I/R group, IPC group presented relatively increase in accumulated length of capillaries, mean cerebral microcirculatory perfusion, and microcirculatory velocity in ischemic and reperfusion phase. There was no-reflow phenomenon in I/R group in reperfusion phase, which was substituted by the course of increasing reperfusion in IPC group.CONCLUSIONS:IPC could relieve the reduction of tissue perfusion during ischemia and the no-reflow phenomenon during reperfusion by improving the regulating function of microcirculation, which relatively promote the opening of capillaries and accelerating of microvascular flow, therefore protect brain from I/R injury.     

Effects of urocortin-I preconditioning on myocardial mitochondrial respiratory function and enzyme activity in rats

ATM: To investigate the influence of urocortin-I (Ucn I) preconditioning on the myocardial mitochondrial respiratory function and enzyme activity in the rats with ischemia reperfusion, and to observe the changes of ATP content in the myocardial cells. METHODS: (1) The healthy male Sprague-Dawley rats were randomly divided into 4 groups:normal group (Nor group), ischemia reperfusion group (IR group), Ucn I preconditioning group (Ucn I group), 5-hydroxy acid (5-HD)+Ucn I group. Langendorff perfusion was used to establish the in vitro model of cardiac ischemia reperfusion. At the end of the balance (T₁), before ischemia (T₂) and at the end of the reperfusion (T₃) respectively, the myocardial mitochondria was extracted, the mitochondrial respiratory function and respiratory enzyme activity in each group were determined. (2) The method of MPA isolated heart perfusion was used to isolate myocardial cells of the adult rats. After cultured for 24 h, myocardial cells were divided into 4 groups:Nor group, hypoxia/reoxygenation group (I/R group), Ucn I group, 5-HD+Ucn I group. Hypoxia/reoxygenation model of myocardial cells was established. At the end of reoxygenation, the changes of myocardial ATP content were measured by high performance liquid chromatography.RESULTS: (1) Compared with T₁, T₂ time points, the respiratory function (state 3 respiratory rate, respiratory control rate) and NADH oxidase, succinate oxidase and cytochrome C oxidase activities at T₃ time point were significantly decreased (P<0.05) in all groups except Nor group. At T₃ time point, the myocardial mitochondrial respiratory function and respiratory enzyme activity in Ucn I group were superior to 5-HD+Ucn I group and IR group (P<0.05), but was inferior to Nor group (P<0.05). At T₃ time point, the respiratory function of myocardial mitochondria and respiratory enzyme activities (NADH oxidase, succinate oxidase) in 5-HD+Ucn I group were better than those in IR group (P<0.05), but no statistical difference of the cytochrome C oxidase activity between the 2 groups was observed. The respiratory function and 3 kinds of respiratory enzyme activities at T₁, T₂ time points had no statistical change. (2) At the end of the reoxygenation, the myocardial ATP content in Nor group was higher than that in other groups (P<0.01). The myocardial ATP contents in I/R group and 5-HD+Ucn I group were lower than that in Ucn I group (P<0.05). In additon, 5-HD+Ucn I group was higher ATP content compared with I/R group (P<0.05). CONCLUSION: Ucn I preconditioning attenuates the ischemia/reperfusion induced damages of myocardial mitochondrial respiratory function and respiratory enzyme activity, thus ensuring the myocardial ATP contents under the condition of hypoxia/reoxygenation.     

Changes in endothelial glycocalyx in ischemia-reperfusion injury and their relationship with microvascular permeability

AIM: To determine the role of the glycocalyx in microvascular permeability. METHODS: Dextran was intravenously injected and quatitatively examined in the rat transient cerebral ischemic model. At the same time, endothelial glycocalyx(anionic sites) was labelled with the probe cationic gold colloid(CGC) using post-embedding technique and examined with electron microscope. RESULTS: The labeling of CGC decreased significantly following ischemia, meanwhile, microvascular permeability to dextran increased. CONCLUSION:Endothelial glycocalyx is very sensitive to ischemia or anoxia. Its disruption may be the initiator of the dysfunction of endothelium and the determinant of increased permeability.     

X-ray irradiation increases sensitivity of myocardium to ischemia/reperfusion injury in rats

AIM：To observe the sensitivity of myocardium to ischemia/reperfusion (I/R) injury in the rats with chest radiotherapy. METHODS：The radiation-induced heart disease model was established by local 20 Gy of X-ray irradiation in the chest. Male Wistar rats (n=42) were randomly divided into 6 groups:sham trauma group, trauma group, sham trauma+sham operation group, sham trauma +I/R group, trauma+sham operation group and trauma+I/R group. The rats were subjected to 30 min of ischemia and 1 h of reperfusion 2 week after trauma. The left ventricular developed pressure (LVDP) and ±dp/dtmax were recorded by BL-410 biological signal recording and analysis system. The serum cardiac troponin I (cTnI) and creatine kinase isoenzyme (CK-MB) were measured by ELISA. The myocardial infarct size was determined by nitroblue tetrazolium(NBT) staining method and BI2000 image analysis software. RESULTS：Compared with sham trauma+I/R group, significant decreases in LVDP and ±dp/dtmax were observed in trauma+I/R group (P<0.01) with significant increases in the infarct size and the concentrations of cTnI and CK-MB (P<0.01). CONCLUSION:Chest X-ray irradiation increases the sensitivity of myocardium to I/R injury in rats.     

Effect of intermittent hypobaric hypoxia preconditioning on expression of Ngb and Bcl-2 in hippocampal CA1 region in rats with global cerebral ischemia-reperfusion

AIM:To study the effect of intermittent hypobaric hypoxia preconditioning (IHHP) on the expression of neuroglobin (Ngb) and Bcl-2 in hippocampal CA1 region in the rats with global cerebral ischemia-reperfusion. METHODS:The Wistar rats were randomly divided into sham group, IHHP control group, global cerebral ischemia-reperfusion group (I/R group), and IHHP+I/R group. The 4-vessel occlusion rat model of Pulsinelli was performed in the rats in I/R group and IHHP+I/R group, in which the common carotid artery was occluded for 8 min before reperfusion. Thionine staining and immunohistochemical staining were used to observe the histological changes of the hippcampus and the expression of Ngb and Bcl-2 in the hippocampal CA1 region. RESULTS:A significant increase in the quantity of surviving cells in the hippocampal CA1 region was observed in IHHP+I/R group as compared with I/R group. There was a significant increase in the expression of Ngb and Bcl-2 in the hippocampal CA1 region in IHHP+I/R group as compared with I/R group. CONCLUSION: Through the up-regulation of hippocampal Ngb and Bcl-2 expression, intermittent hypobaric hypoxia preconditioning may play a role in neuroprotection by reducing hippocampal neuronal apoptosis from ischemia-reperfusion.     

Effect of fucoidan on intestinal ischemia-reperfusion injury in rats

AIM:To investigate the effect and potential mechanism of fucoidan on intestinal ischemia-reperfusion (I/R) injury in rats. METHODS:Adult male Wistar rats were randomly divided into 3 groups:sham group, I/R group and Fucoidan+I/R group. Fucoidan at 160 mg/kg was intraperitoneally injected in rats of Fucoidan+I/R group 7 d prior to operation, and the equal volume of saline was intraperitoneally injected in rats of sham group and I/R group. The rats in I/R group and Fucoidan+I/R group underwent superior mesenteric artery occlusion for 1 h and then reperfusion for 2 h. Following reperfusion, the histomorphological changes of the ileum were examined by HE staining. The levels of diamine oxidase (DAO), D-lactic acid (D-LA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β were detected in the blood samples, the levels of malondialdehyde (MDA) and glutathione (GSH), the activity of superoxide dismutase (SOD) and myeloperoxidase (MPO), and the protein levels of Bax, cleaved caspase-3 and Bcl-2 were analyzed in intestinal tissue samples. RESULTS:Compared with sham group and Fucoidan+I/R group, the serum levels of DAO, D-LA, TNF-α, IL-6 and IL-1β were significantly increased in I/R group (P<0.05), Chiu's score of intestinal tissue, MDA content, MPO activity, the levels of Bax and cleaved caspase-3 protein in the intestinal tissues were also significantly increased (P<0.05), while the tissue GSH content, SOD activity, and Bcl-2 protein levels were significantly decreased (P<0.05). CONCLUSION:Fucoidan attenuates intestinal tissue damage caused by I/R, which may be related to anti-oxidation, anti-inflammatory and anti-apoptotic effects.     

Effects of volatile anesthetics on rat heart ischemia-reperfusion injury in vitro

AIM: To investigate the effect of volatile anesthetics on function,metabolism,ATPase activity and free radicals in isolated ischemia /reperfusion (I/R) rat hearts.METHODS: 136 SD rats were anesthetized with pentobarbital and randomly divided into six groups and 17 sub-groups (n=8),according to the given drug.In a normal thermal isolated Langendorff rat heart model,four volatile anesthetics in 1.5 MAC concentration were given before global ischemia 25 min and during reperfusion 30 min.Coronary flow (CF),LVEDP,left ventricular developed pressure (LVDP),±dp/dt were monitored at 15 min of equilibrium,15 min of drug treatment,the end of reperfusion.Myocardial adenosine triphosphate (ATP),malodialdehyde (MDA),activity of Ca2＋-ATPase and Na＋-K＋-ATPase,and superoxide dismutase (SOD) were determined at 15 min of equilibrium,15 min of drug treatment or absence,10 min global ischemia and the end of reperfusion.RESULTS: CF and LVEDP were increased significantly after exposured to volatile anesthetics 15 min,and LVDP,+dp/dtmax were significantly decreased.However,LVDP and +dp/dtmax were increased at the end of reperfusion in the treated groups.HR in halothane and isoflurane groups was decreased before ischemia and after reperfusion.The myocardial ATP content was significantly increased before and after ischemia in the treated groups.At the end of reperfusion,the activity of SOD was significantly higher and myocardial MDA content was significantly lower in the treated groups than those in control group.The activity of Ca2＋-ATPase,compared with the control group,was markedly decreased before ischemia in halothane,enflurane and isoflurane group.Nonetheless,the activity of Ca2＋-ATPase was clearly increased in the treated groups during ischemia and at the end of reperfusion.The activity of Na＋-K＋-ATPase was only enhanced in halothane group at the end of reperfusion among groups.CONCLUSION: The volatile anesthetics depress myocardial systolic function.There are markedly protective effects against myocardial I/R injury.Meanwhile,the volatile anesthetics improve the recovery of function and metabolism,and increase CF and the activity of Ca2＋-ATPase and Na＋-K＋-ATPase in rats.     

Establishment and evaluation of rat heart ischemia-reperfusion injury model in vivo

AIM: To establish and evaluate a rat model of heart ischemia-reperfusion injury in vivo. METHODS: Seventy-two male Sprague-Dawley rats weighing(250±50)g were randomly divided into sham operation group(sham), ischemia-reperfusion group(I/R) and normal group. The animals were anesthetized and heparinized. Myocardial ischemia-reperfusion was induced by ligating the left anterior descending coronary artery with "U-shape tube" for 35 min followed by 120 min or 240 min reperfusion in vivo. The heart infarct size was measured by triphenyltetrazolium chloride(TTC) staining. The myocardial cell apoptotic index was determined by the method of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling(TUNEL). Immunohistochemical method was used to detect the expression of Bcl-2 and Bax in rat ischemia myocardium. The blood level of MB isoenzyme of creatine kinase(CK-MB),cardiac troponin I(cTnI),nitric oxide(NO),malondialdehyde(MDA), total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px) were detected after reperfusion for 2 h and 4 h. RESULTS: Compared with normal group and sham group, there were obvious changes of ST-T segment and Q wave in the electrocardiogram of I/R group. The blood level of CK-MB, cTnI, NO, MDA and GSH-Px in I/R group increased(P<0.05,P<0.01) after reperfusion for 2 h and 4 h, and the blood level of T-SOD in I/R group after reperfusion for 2 h and 4 h also increased(P<0.05). The heart infarct size in I/R group was the largest as compared to other groups. Among these groups, the apoptotic index of I/R group was the highest and the Bcl-2/Bax ratio in I/R group decreased(P<0.01).CONCLUSION: The rat model of heart ischemia-reperfusion injury in vivo can be successfully established with the "U-shape tube". There are obviously changes of heart infarct size, blood level of CK-MB, cTnI, NO, MDA, T-SOD and GSH-Px, myocardial apoptotic index and Bcl-2/Bax ratio between I/R rats and control animals.     

Lactulose preconditioning protects against intestinal ischemia-reperfusion injury in rats

AIM: To investigate the protective effect of lactulose preconditioning on intestinal ischemia-reperfusion (IR) injury in rats. METHODS: Thirty Sprague-Dawley rats were randomly divided into 3 groups: sham operation group, IR group and IR plus lactulose preconditioning group. Lactulose was intragastrically administered in lactulose group 7 days prior to operation, and the equal volume of saline was administered in the other 2 groups. The intestinal IR injury was induced in IR group and IR+lactulose group using bulldog clamps on superior mesenteric artery by 30 min of ischemia followed by 60 min of reperfusion. Following reperfusion, the serum samples were collected for estimating the levels of interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and IL-1β. Segments of terminal jejunum were rapidly fixed in 4% paraformaldehyde, and HE staining was applied to assess the histopathology. Apoptosis in intestinal epithelium was determined by the technique of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The samples of terminal jejunum were also taken for measuring malondialdehyde,superoxide dismutase and the expression of cleaved caspase-3. RESULTS: Lactulose preconditioning significantly attenuated the severity of intestinal IR injury, with inhibition of IR-induced apoptosis. Moreover, lactulose preconditioning significantly limited the release of cytokines and lipid oxidation. CONCLUSION: Lactulose preconditioning has a protective effect on intestinal ischemia reperfusion by inhibiting IR-induced apoptosis and oxidative stress.     

Effects of propofol on levels of amino acid and neuronal apoptosis of hippocampus after global ischemia-reperfusion in rats

AIM:To investigate the effects of propofol on levels of amino acid and neuronal apoptosis of hippocampus after global ischemia-reperfusion in rats．METHODS:60 male Wistar rats were randomly assigned to five groups ( twelve animals each)．After global cerebral ischemia for 10 min then reperfusion for 60 min and 72 h,the animals were decapitated and the brains were removed respectively．HPLC was adopted to measure the contents of amino acids in hippocampus．The density of apoptosis neurons in the hippocampal CA1 subfield was evaluate with light microscope．Flow cytometry technique was applied to detect the neuronal apoptosis index in the hippocampus．RESULTS:The contents of Glu and Asp increased markedly and the levels of GABA and Gly decreased obviously in hippocampus after ischemia-reperfusion. The levels of Glu and Asp were lower in propofol group than those in control group (P<0.05 or P<0.01),and the contents of GABA and Gly were higher in propofol group than those in control group (P<0.05 or P<0.01). Apoptosis index and density of apoptosis neurons in the hippocampus were higher in control group than those in propofol group. CONCLUSION:Propofol inhibits neuronal apoptosis of hippocampus after global ischemia-reperfusion,and suppresses the excessive release of excitory amino acids and the exhaustion of inhibitory amino acids in hippocampus after ischemia-reperfusion. Its mechanism may be related with decreasing the neuronal apoptosis.     

Protective effects of liposomes containing L-arginine,Se and taurine on intestinal ischemia-reperfusion injury in rats

AIM and METHODS:To study the protective effects of liposomes containing L-Arg,Se and taurine on intestinal ischemia-reperfusion injury in rats. Wistar rats were divided randomly into sham operated group,ischemia-reperfusion(I/R) group,pretreatment with liposomes group and treatment with liposomes at reperfusion group. In the experiments, superior mesenteric artery was clipped for 60 min, and then unclipped. 2 hours of reperfusion later, MDA content, T-SOD and Ca²⁺-Mg²⁺-ATPase activities in intestinal tissues were detected respectively, ultrastructure and bcl-2 expression in intestinal mucosa tissue were observed.RESULTS:MDA content in liposomes-treated group was less than I/R group (P＜0.01).The activities of T-SOD and Ca²⁺-Mg²⁺-ATPase in liposomes-treated group were higher than I/R group(P＜0.01). Bcl-2 staining was negative in I/R group, and was positive in liposomes-treated group (P＜0.01).There was no difference in above indexes between pretreatment with liposomes group and treatment with liposomes at reperfusion group(P＞0.05). CONCLUSION:Liposomes containing L-arginine, Se and taurine can protect intestine against ischemia-reperfusion injury in rats,which may be related to inhibiting lipid peroxidation, stabilizing internal circumstances and inducing bcl-2 protein expression.     

Effects of HES 130/0.4 on no-reflow after myocardial ischemia-reperfusion injury in rats

AIM: To observe the effects and mechanisms of hydroxyethylstarch(HES) 130/0.4 on no-reflow phenomenon after myocardial ischemia-reperfusion in rats. METHODS: SD rats were randomly divided into 4 groups:sham operation group, ischemia-reperfusion(IR, treated with normal saline) group, normal saline ischemia-reperfusion(NS-IR, treated with NS) group and HES ischemia-reperfusion(HES-IR, treated with HES) group. Myocardial infarct size and no-reflow range were determined by staining methods, and the activities of myocardial enzymes(CK-MB, cTnI and MPO) were measured. Meanwhile, cardiac microvascular endothelial cells of the rat were cultured and divided into 4 groups:control group, hypoxia/reoxygenation(H/R) group, NS-H/R group and HES-H/R group. Acute ischemia reperfusion models were simulated, and the concentration of calcium ions was measured. The relative cell activity was evaluated by CCK-8 assay, and the apoptotic rate was detected by flow cytometry. RESULTS: In HES-IR group, the myocardial infarct size, the no-reflow zone, CK-MB, cTnI and MPO activity were all significantly lower than those in IR group(P<0.05). In microvascular endothelial cells, the concentration of calcium ions and the apoptotic rate in HES-H/R group were significantly decreased, while the relative cell activity increased compared with H/R group(P<0.05). CONCLUSION: HES reduces no-reflow in acute myocardial ischemia-reperfusion. The mechanism may be involved in the inhibition of both the infiltration of neutrophils and the calcium overload of endothelial cells.     

Beclin-1 expression is upregulated by spermine in rat myocardial ische-mia-reperfusion injury

AIM: To observe the effects of spermine (SP) on myocardial ischemia-reperfusion (IR) injury in rats. METHODS: SD rats (weighing 220~250 g) were equally randomized to 3 groups:sham control group, in which the rats were only treated with thoracotomy; IR group, in which the rats were treated with ischemia for 30 min and reperfusion for 60 min; and IR+SP group, in which 0.5 mmol/L SP (2 mL/kg) was intravenously injected just 15 min before reperfusion. The morphological changes of myocardial tissues were assessed by HE staining. The levels of cardiac troponin I (cTnI) and creatine kinase isoenzyme MB (CK-MB) in plasma were determined. Myocardial infarct size and no-reflow range of the myocardium were measured by Evans blue and thioflavin S staining. Inflammatory responses in the myocardial tissues were detected by myeloperoxidase (MPO) assay. The autophagy function was detected by measuring the protein expression of beclin-1 by Western blot. RESULTS: The myocardial injury and inflammatory infiltration in IR+SP group were reduced under light microscope. Treatment with SP decreased the plasma levels of cTnI and CK-MB, and reduced the IR-induced infarct size and no-reflow range size of the left ventricle (P<0.05). Tissue MPO assay showed that myocardial inflammatory responses were attenuated in IR+SP group compared with IR group. Beclin-1 was upregulated in IR+SP group compared with IR group (P<0.05). CONCLUSION: Exogenous SP attenuates myocardial ischemia-reperfusion injury by upregulating the expression of beclin-1.     

Advances in the mechanism of retina ischemia-reperfusion injury

Retinal ischemia-reperfusion injury (RIRI) is a common cause of visual impairment and blindness. At the cellular level, ischemic and reperfuion retinal injury consists of a self-reinforcing destructive cascade involving oxidative stress initiated by energy failure, inflammatory reaction, calcium influx, increased glutamatergic stimulation and neuronal depolarisation and apoptosis. A number of animal models and analytical techniques have been used to study the retinal ischemia-reperfusion injury, we now understand much better than ever before in the mechanism of RIRI, and an increase in the therapeutic strategies has been developed experimentally to attenuate the detrimental effects of retinal ischemia-reperfusion injury. Thus far, however, success in the laboratory has not been translated to the clinic. Given the increasing understanding of the events involved in ischemia-reperfusion neuronal injury, it is hoped that clinically effective treatments for retinal ischemia-reperfusion injury will soon be available.