Effects of heptanol preconditioning on structure,function and Cx43 content of mitochondria in rabbit model of myocardial ischemia/reperfusion injury

AIM: To investigate the effects of heptanol preconditioning on the changes of structure, function and connexin 43 (Cx43) content in mitochondria in a rabbit model of myocardial isehemia-reperfusion (IR) injury. METHODS: In anesthetized open-chest rabbits, the left anterior descending artery (LAD) was occluded for 30 min and reperfused for 4 h. Sixty-four rabbits were randomly divided into 4 groups (n=16 in each group): sham operation group (sham group), ischemia-reperfusion group (IR group), ischemic preconditioning group (IP group) and heptanol preconditioning group (HT group). All rabbits in the 4 groups were killed 4 h after reperfusion. Myocardial infarct size was determined at the end of the experiment. Mitochondria was isolated by centrifugations. The ultrastructural changes of the mitochondria were observed under electronic microscope. The mitochondrial membrane potential, Ca2+ concentration, MDA content and SOD activity of myocardial mitochondria were also examined. The content of mitochondria Cx43 was detected by Western blotting. RESULTS: Compared to IR group, the myocardial infarct size was significantly reduced in IP (18.97%±2.80%) and HT (19.97%±3.80%) groups, the damage of mitoehondrial ultrastructure was milder (P<0.05), mitochondrial membrane potential was significantly higher and Ca2+ concentration was much lower (P<0.01) in IP group and HT group. No significant difference of MDA content and SOD activity in myocardial mitochondria between IR group and HT group was found. However, MDA content were much lower and SOD activity was significantly higher in IP group as compared to IR group (P<0.01). Compared to sham group, the mitochondria Cx43 expression was distinctly decreased compared to IR group (P<0.05) and no significant difference was found between IP group and HT group (P>0.05). CONCLUSION: Heptanol preconditioning protects myocardium from ischemia-reperfusion injury. The mechanism may be related to increasing in mitochondrial membrane potential, alleviating Ca2+ overload in myocardial mitochondria and attenuating the decrease in mitochondria Cx43 expression induced by isehemia-reperfusion.     

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.     

Protective effects of physcion against cerebral injury induced by ischemia-reperfusion in rats

AIM: To explore the effect of physcion (P) on the level of IL-1β and expression of ICAM-1 and caspase-3 during cerebral ischemia-reperfusion injury. METHODS: The 91 healthy adult SD rats were selected, and were randomly divided into normal group, sham-operated group, cerebral ischemia-reperfusion group (model), low-dose physcion (PLD) and high-dose physcion (PHD) treatment group. The level of IL-1β was detected by radioimmunoassay. The expression of ICAM-1 and caspase-3 was detected by immunohistochemistry. The changes of tissue pathology were also investigated. RESULTS: The level of IL-1β reached the peak at 6 h after ischemia-reperfusion (IR). The protein expression of ICAM-1 and caspase-3 reached the peak at 24 h after IR. The level of IL-1β and the protein expression of ICAM-1 and caspase-3 in PHD group decreased obviously compared with those in model group (P<0.05 or P<0.01), infiltration and adhesiveness of neutrophils were less serious at the same time. CONCLUSION: Physcion decreases the level of IL-1β and the protein expression of ICAM-1 and caspase-3 to protect brain tissue from cerebral ischemia-reperfusion injury.     

Effect of epigallocatechin gallate on cardiomyocyte apoptosis induced by ischemia-reperfusion in rats

AIM: To observe the effects of epigallocatechin gallate (EGCG) on cardiomyocyte apoptosis induced by ischemia-reperfusion (IR) in rats. METHODS: The left anterior descending branch of coronary artery was ligated for 30 min and reperfused for 60 min to make a the myocardial ischemia-reperfusion model in rats. The experiment was divided into five groups: sham, ischemia/reperfusion (IR), EGCG (10 mg/kg and 20 mg/kg) and salvia miltiorrhizae (SM, 100 mg/kg) group. The apoptotic cardiomyocytes were detected by in situ end labeling method, and the expressions of Bcl-2 and Bax were shown through immunohistochemistry method. RESULTS: There was no apoptosis myocardial cell in sham operation group. The apoptosis index and expression of bax significantly increased, and bcl-2/bax reduced in IR group (P<0.01). In EGCG-treated group, however, the changes above were obviously alleviated (P<0.01). CONCLUSION: EGCG significantly inhibits cardiomyocyte apoptosis in ischemia-reperfusion rat hearts. The possible mechanism is to raise the ratio of Bcl-2/Bax proteins by increasing in the expression of bcl-2 gene and decreasing in the expression of bax gene.     

Protective effect of rapid ischemic preconditioning against spinal cord ischemic injury in rabbits

AIM: To evaluate the protective effect of rapid phase of ischemic preconditioning against spinal cord ischemic injury in rabbits. METHODS: Thirty six male New Zealands white rabbits were randomly assigned to 3 groups (12 in each group): ischemia and reperfusion injury group (IR group), ischemic preconditioning + IR group (IPC+IR group) and sham operation group (sham). In IR group, spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min; The rabbits in IPC+IR group underwent a 6 min ischemic preconditioning followed by 30 min of reperfusion before the 20 min clamping; The rabbits in sham group underwent the same procedures as the IR group except for infrarental aortic unclamping. Neurologic status was scored at 8, 12, 24 and 48 h after reperfusion. All animals were sacrificed at 48 h after reperfusion and the spinal cords (L_5-7) were removed for histopathologic study and determination of the activity of Na⁺, K⁺-ATPase. RESULTS: The neurologic function scores in sham group and IPC+IR group at each observation interval were higher than those in IR group (P＜0.01). Compared to IR group, there were more normal neurons in anterior horn of spinal cord in sham group and IPC+IR group (P＜0.01); the activity of Na⁺, K⁺-ATPase in sham group and IPC+IR group were higher than those in IR group (P＜0.01). CONCLUSION: The rapid phase of ischemic preconditioning has a protective effect against spinal cord ischemic injury in rabbits, and this neuroprotection may be related to the maintenance of Na⁺, K⁺-ATPase activity.     

Protective effect of fluvastatin on ischemic reperfused myocardium in rabbits

AIM: To investigate the protective effect of fluvastatin and its influence on ICAM-1 mRNA expression in ischemia/reperfusion myocardium of normocholesterolemic rabbits. METHODS: 24 rabbits were divided into three groups randomly and myocardial ischemia/reperfusion model in the rabbit was made. Rabbits were subjected to 45 min of regional myocardial ischemia and 2 h of reperfusion. 10 mg·kg－1·d－1 fluvastatin were administered for one week. Dynamic index of blood flow was recorded and analyzed. Serum activity of CK, CKMB, LDH and LDH-1 were measured. The expression of ICAM-1 mRNA in ischemic myocardium was detected with semi-quantitative RT-PCR. RESULTS: In comparison with control group, pretreatment with fluvastatin decreased LVEDP at the whole observed duration, and spontaneously increased ±dp/dtmax. Serum activities of CK, CKMB and LDH-1 in control group were significantly higher than those in sham group, but heavily reduced in fluvastatin group. Increased expression of ICAM-1 mRNA due to ischemia reperfusion was reduced significantly in fluvastatin group compare to control group. CONCLUSION: Pretreatment of fluvastatin may reduce inflammation reaction in reperfused myocardium, and this may contribute to its protective effect against experimental myocardial ischemia reperfusion injury.     

Role of heme oxygenase-1/carbon monoxide system in pulmonary ischemia-reperfusion injury

AIM: To investigate the effect of heme oxygenase-1 (HO-1)/carbon monoxide (CO) system on pulmonary ischemia-reperfusion injury (PIRI) in rabbits. METHODS: Single lung ischemia and reperfusion animal model was used in vivo. The rabbits were randomly divided into three groups (n=10 in each), control group (C), PIR group (I-R), PIR+ hemin group (H) and PIR+zinc protoporphyrin IX (ZnPP) group (Z). Changes of several parameters which included plasma carboxyhemoglobin (COHb) at different time points, wet to dry ratio of lung tissue weight (W/D), the injured alveoli rate (IAR) and the HO-1 enzymatic activity were measured at 180 min after reperfusion in lung tissue. The tissue slides were also stained by immunohistochemistry (IHC) and in situ hybridization (ISH) for HO-1 to detect the expression of HO-1 in lung and to analyze the optical density. The lung tissue was prepared for electron microscopic observation at 180 min after reperfusion. RESULTS: The plasma content of COHb in I-R, H, and Z group increased in a time-dependent manner after I-R. But the increment of H group was higher than that of I-R group, while that of Z group was lower. The HO-1 activity in lung tissue was highest in H group, followed by IR group, Z group, and C group (P<0.05 and P<0.01). Except C group, HO-1 was upregulated in all other groups in the pulmonary endothelial cells, part of pulmonary vascular smooth muscle cells, extima of vessels and epithelial cells of airway. H group had the highest average optical density value, then the IR group, Z group and C group (P<0.05 and P<0.01). The value of W/D and IAR was highest in Z group, the second was in IR group, then the H group and C group (P<0.05 and P<0.01). The abnormal changes of the lung tissue in morphology in I-R group, Hemin treatment mitigated the injury of I-R in H group and ZnPP exacerbated the impairment of ultrastructure in Z group were also observed. CONCLUSION: HO-1/CO system possesses notable protective effects on lung during pulmonary ischemia-reperfusion injury in rabbits.     

Effects of heat shock protein 70 on inflammation after hepatic local ischemia/reperfusion in rats

AIM:To study the effects of heat shock protein 70 (HSP70) induced by the heat stress pretreatment on inflammation after hepatic ischemia/resperfusion.METHODS:With the hepatic local ischemia/reperfusion model (IR group),heat stress pretreatment (H+IR group) and injecting quercetin before heat stress pretreatment (Q+H+IR group) were performed.The HSP70,intercellular adhesion molecule-1 (ICAM-1) and the myeloperoxidase (MPO) activity were detected.The levels of serum ALT and AST and histological changes of the hepatocytes were also observed.RESULTS:In H+IR group,the HSP70 expression was higher than that in other groups at each time point,after performing ischemia-perfusion,hepatic injury was slighter.The levels of serum ALT and AST were increased slightly (P<0.01).The expression of ICAM-1 and the changes of MPO activity increased and peaked respectively at 6 h and 12 h after reperfusion.However,they were lower in H+IR group than those in IR group and Q+H+IR group.CONCLUSION:The HSP70 induced by heat stress pretreament reduces the expression of ICAM-1 and the changes of MPO activity during hepatic ischemia-reperfusion,then hepatic injury is depressed from the inflammation.     

Effects of Liqustrazin on respiratory enzymes in the myocardial mitochondria of the ischemia-reperfusion rats

AIM: To study the effects of Liquestrazin on succinic dehydrogenase (SDH) and cytochrome oxidase (CCO) in the myocardial mitochondria of the ischemia-reperfusion rats and its mechanism. METHODS:Model of myocardial ischemia-reperfusion injury was produced by coronary artery ligation . The rats were devided into sham operation control (SC), ischemia-reperfusion (IR) and ischemia-reperfusion protected with Liqustrazin (IR+L) group . Activity of SDH,CCO,SOD and GSH·PX and contents of malondialdehyde (MDA),Cyt aa₃,Cyt c and phospholipid(PL) were observed respectively . RESULTS: As compared with ischemia-reperfusion group (IR), IR+L group showed significantly increased activity of SDH, CCO,SOD and GSH·PX (P＜0.01) , MDA content decreased significantly , the contents of Cyt aa₃ , Cyt c and PL increased respectively . CONCLUSION : Liqustrazin has notable antagonistic effects on decrease in SDH and CCO activities in the myocardial mitochondria of the ischemia-reperfusion rats , which is due to its oxygen free radicals scavenging action and its anti-lipid peroxidation reaction.     

Effects of prostaglandin I2 on mesenteric microcirculation and property of hemorheology in rabbits with renal ischemia/reperfusion injury

AIM: To explore the effects of prostaglandin I2 (PGI2) on mesenteric microcirculation and hemorheology during renal ischemia/reperfusion (IR) injury. METHODS: 36 rabbits were randomly distributed into the sham operated group (sham group)， renal ischemia/reperfusion injury group (IR group) and PGI2+IR group（PGI2 group）. IR group received clamping for 60 min followed by 120 min of reperfusion. A microcircular microscope image analysis system was used to study the changes of mesenteric microcirculation and hemorheology at 60 min of ischemia and 120 min of reperfusion, respectively， while the blood samples were obtained for the measurement of hemorheological indexes. RESULTS: ① In IR group during the period of renal IR， the number of adhesive leukocytes and microthrombus， hemorrhage and hemorheological indexes such as blood viscosity， plasma viscosity， blood reduction viscosity， hematocrit， erythrocyte aggregation index， erythrocyte sedimentation rate， erythrocyte sedimentation rate K and plasma fibrinogen were significantly higher， while microvascular diameters， blood flow velocity and erythrocyte deformation index were significantly lower compared with sham group (P＜0.01 or P＜0.05). ② PGI2 5-40 ng·kg-1·min-1) affected the indexes of mesenteric microcirculation and hemorheology to different extent. In 10 ng·kg-1·min-1 PGI2 group， the diameters of arteriole and venule， blood flow velocity， the number of adhesive leukocytes， microthrombus， hemorrhage and hemorheological indexes significantly changed， compared with IR group (P＜0.01 or P＜0.05). Except that microvascular diameters increased remarkably （P＜0.01）， others showed no significant difference compared to sham group （P＞0.05）. CONCLUSIONS: PGI2 ameliorates the disturbance of mesenteric microcirculation and hemorheology caused by renal IR injury with the best effect at 10 ng·kg-1·min-1.     

Effects of glucagon-like peptide-1 on myocardial ischemia-reperfusion/hypoxia-reoxygenation injury in rats

AIM: To investigate the effects of glucagon-like peptide-1 (GLP-1) on myocardial ischemia-reperfusion (IR)/hypoxia-reoxygenation (HR) injury in rats. METHODS: Sprague-Dawley rats were randomly divided into 5 groups: sham group, IR group and IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. IR group and IR+GLP-1 group were subject to 30 min of ischemia and 3 h of reperfusion. The myocardial infarct size, the ultrastructural changes of the myocardial tissues, the apoptosis of the cardiomyocytes, the activity of superoxide dismutase (SOD) and the concentration of malondialdehyde (MDA) were detected. Primarily cultured cardiomyocytes were divided into 5 groups at random: control group, HR group and HR+GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) groups. The morphology and apoptosis of the cardiomyocytes were observed. The levels of lactate dehydrogenase (LDH),MDA,SOD,reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in different groups were detected. RESULTS: Compared with IR group, the myocardial infarct size and cardiomyocyte apoptosis were remarkably reduced, mitochondrial ultrastructures were improved, the activity of SOD was increased and the concentration of MDA was decreased in IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. Compared with HR group, GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) preconditioning significantly decreased the myocardial injury, increased SOD activity, decreased MDA concentration and ROS production, and heightened MMP in a dose-dependent manner. CONCLUSION: GLP-1 protects cardiomyocytes from IR/HR injury, which may be partially due to the effects of anti-oxidative mechanism and the function of mitochondrial protection.     

Effects of simvastatin on expression of Bcl-2 and Bax in myocardium of rats with renal ischemia-reperfusion injury

AIM: To observe the effect of simvastatin on myocardial tissue after renal ischemia-reperfusion injury and its mechanism. METHODS: A rat model of renal ischemia-reperfusion injury was prepared by clamping the bilateral renal arteries for 45 min. The rats (n=36) were randomly divided into sham operation group, renal ischemia-reperfusion (I/R) group and simvastatin group with 12 rats in each group. The content of serum creatinine (SCr), blood urea nitrogen (BUN) and myocardial tissue malondialdehyde (MDA), the myocardial activity of lactate dehydrogenase (LDH), creatine kinase (CK) and superoxide dismutase (SOD), and the myocardial protein expression of Bcl-2 and Bax were detected. RESULTS: Compared with sham operation group, the content of SCr, BUN and myocardial MDA, and the myocardial activity of LDH and CK in I/R group were significantly increased (P<0.05), and the activity of SOD was significantly decreased (P<0.05). Compared with I/R group, the content of SCr, BUN and myocardial MDA, and the myocardial activity of LDH and CK in simvastatin group were significantly decreased (P<0.05), while SOD activity was enhanced (P<0.05). The protein expression of Bcl-2 and Bax in sham operation group was less than that in I/R group (P<0.05), and the protein level of Bax in simvastatin group was significantly lower than that in I/R group (P<0.05), while the protein level of Bcl-2 was increased (P<0.05). CONCLUSION: Simvastatin has a protective effect on the myocardium of the rats with renal ischemia-reperfusion injury, and the protective mechanism may be related to the elimination of free radicals by simvastatin, increase in the protein expression of Bcl-2 and decrease in the protein expression of Bax.     

Effects of icariin preconditioning on inflammatory responses in myocar-dial ischemia-reperfusion injury

AIM:To observe the effects of icariin on myocardial ischemia-reperfusion injury. METHODS:The left anterior descending coronary artery was ligated for 30 min and then loosened for 2 h to establish the rat model of myocardial ischemia-reperfusion injury. Forty-eight healthy adult male SD rats weighing 250~300 g were randomly divided into sham group, model group, low-, middle-and high-dose icariin groups, and aspirin group. The morphological changes of the myocardium were observed by HE staining. The protein expression of NF-κB p65 in the myocardial nucleus was determined by the method of immunohistochemistry. The content of tumor necrosis factor α (TNF-α) in the myocardial tissues was detected by Western blotting. The level of interleukin 1β (IL-1β) in the serum was measured by ELISA. The activity of myeloperoxidase (MPO) in the myocardial tissues was assayed by colorimetry. RESULTS:Compared with sham group, TNF-α content, IL-1β concentration, NF-κB expression and MPO activity in all other groups increased. Compared with model group, TNF-α content, IL-1β concentration, NF-κB expression and MPO activity in low-, middle- and high-dose icariin groups and aspirin group all decreased. No significant difference of the above parameters between high-dose icariin group and aspirin group was observed. CONCLUSION: Icariin preconditioning reduces inflammatory responses in the process of myocardial ischemia-reperfusion injury in a dose-dependent manner.     

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 Xijiao Dihuang and Yinqiao San decoction on ICAM-1 and VCAM-1 expression in mouse lung tissues and rat pulmonary microvascular endothelial cells infected with influenza virus

AIM：To investigate the effects of Xijiao Dihuang and Yinqiao San decoction (XDY) on the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in mouse lung tissues and rat pulmonary microvascular endothelial cells (RPMVECs) infected with influenza virus, and to explore its mechanism for treatment of viral pneumonia. METHODS：Fifty-four male BALB/c mice were randomly divided into normal group, model group and XDY group (n=18 in each group). The viral pneumonia model was established by intranasally dripping influenza A (H1N1) virus into the mice. The mice in XDY group were treated with XDY 1 h after dripping the virus. The expression of ICAM-1 and VCAM-1 in lung tissues was examined by immunohistochemical staining 2, 4 and 6 d after infection. On the other hand, RPMVECs were obtained from male Wistar rats and primarily cultured. The cells were randomly divided into control group, virus group, virus+XDY group, tumor necrosis factor α (TNF-α) group and TNF-α+XDY group. The mRNA and protein expression of ICAM-1 and VCAM-1 was evaluated by real-time PCR and flow cytometry 24 h after infection. RESULTS：Virus exposure increased ICAM-1 and VCAM-1 expression in mouse lung tissues (P<0.01), and XDY treatment attenuated this effect (P<0.01). Virus and TNF-α both led to the increases in mRNA and protein expression of ICAM-1 and VCAM-1 in RPMVECs (P<0.01), which were also reduced by treatment with XDY (P<0.01). CONCLUSION：Treatment with XDY decreases virus-induced ICAM-1 and VCAM-1 expression, suggesting an important role of XDY in treatment of viral pneumonia.     

Polydatin downregulates TLR4 expression in lung ischemia reperfusion injury in rabbits

AIM: To explore the influence of polydatin (PD) on Toll-like receptor 4 (TLR4) signal transduction pathway during lung ischemia reperfusion injury in rabbits. METHODS: Rabbit lung model of ischemia reperfusion (IR) injury was constituted in vivo. Thirty rabbits were divided into groups randomly: control (C), IR and PD group, respectively. The concentration of endotoxin (ET) in plasma was analyzed by end-point chromogenic assay. The protein expressions of TLR4, nuclear factor (NF)-κB p65 and heat shock protein 70 (HSP70) were measured by immunohistochemistry. The intracellular adhesion molecule-1 (ICAM-1) mRNA expression was detected by in situ hybridization histochemistry. The ultrastructural changes were observed by electron microscope. RESULTS: No significant difference of ET concentration in plasma between groups (all P>0.05) was observed. The protein expressions of TLR-4, NF-κB p65, HSP70 and ICAM-1mRNA in IR group were significantly increased as compared to C group and PD group, while those expressions in PD group were evidently higher than those in C group (all P<0.01). The lung pathological injuries in PD group were obviously alleviated as compared to IR group under electron microscope. CONCLUSION: It suggests that lung ischemia reperfusion releases endogenous ligands of TLR4 as HSP70, then activates NF-κB, promotes the release of mediators of inflammation such as ICAM-1. PD might have a protective effect on lung ischemia reperfusion injury by regulating TLR4 signal transduction pathway.     

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.     

Effects of Tertram ethylpyrazine on expression of Fas/FasL mRNA in lung tissue with ischemia-reperfusion injury in rabbits

AIM: To study the expression of Fas/FasL mRNA in lung tissue with ischemia-reperfusion lung injury in rabbits and the relationship with the apoptosis,and to observe the effects of Tertram ethylpyrazine on them.METHODS: The pulmonary ischemia-reperfusion models in rabbits with occlusion of left pulmonary hilum for 1 h and then reperfusion 1,3,5 h respectively were used in this experiment.In TMP group,Tertram ethylpyrazine was intravenously dropped at dose of 60 mg/kg at 1 h before ischemia.The TUNEL technique was used to explore apoptotsis of pulmonary cells.In situ hybridization was performed on the rabbit lung tissue to assay the expression of Fas/FasL mRNA.RESULTS: Apoptosis of pulmonary cells was found in both IR group and TMP group.Compared with group IR,the apoptosis index (AI) was decreased obviously in group TMP (P<0.01).There was a significant positive correlation between the expression of Fas/FasL mRNA and the apoptosis of pulmonary cells (r₁=0.900,r₂=0.869,P<0.01).CONCLUSION: The activation of Fas/Fas-L system may contribute significantly to induce pneumocyte apoptosis in pulmonary ischemic injury.Tertram ethylpyrazine inhibits the activation of Fas/FasL system to decrease apoptosis in pulmonary tissue,which may protect the pulmonary tissues in ischemia injury.     

Effect of ischemic post-conditioning on Egr-1 and IL-1β expression in ischemia-reperfusion injured lung in rats

AIM: To investigate the protective effects of ischemic post-conditioning on the expression of early growth response factor 1 (Egr-1) and interleukin-1β(IL-1β) in ischemia-reperfusion injured lung in rats. METHODS: The model of lung ischemia-reperfusion injury was established in 24 rats and the rats were randomly allocated to 3 different groups (n=8 in each group): (1) sham group: only sham operation (thoracotomy) and no ischemia for 3 h; (2)ischemia-reperfusion group (I/R group): interruption of pulmonary perfusion and ventilation for 1 h followed by reperfusion for 2 h; (3) ischemic post-conditioning group (IPostC group): ischemic post-conditioning (5 min of reperfusion and 5 min of ischemia for 3 times) between the end of ischemia and the beginning of the reperfusion followed by reperfusion for 1.5 h. The lung tissues (prepared to small pieces of about 20 mg) were collected and homogenized at the end of the experiment. The concentration of myeloperoxidase (MPO) in the homogenate was determined. The wet to dry weight ratio (W/D) of the lung tissues was also measured at the end of reperfusion. The pathological changes of the lung tissues were observed under light microscope after reperfusion. The mRNA expression of Egr-1 and IL-1β in the lung tissues was detected by RT-PCR. RESULTS: Compared with sham group, the mRNA expression of Egr-1 and IL-1β, the levels of MPO and W/D were significantly increased in I/R group (P<0.05). The inflammatory responses of the lungs in I/R group were significantly severer than those in sham group. Compared with I/R group, the mRNA expression of Egr-1 and IL-1β, the levels of MPO and W/D in IPostC group were significantly decreased (P<0.05). The inflammatory responses of the lungs in IPostC group were also significantly attenuated. CONCLUSION: Ischemic post-conditioning significantly reduces ischemic reperfusion injury of the lung by inhibiting the expression of Egr-1 and IL-1β.     

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.