全国设施蔬菜生产可持续发展学术研讨会在沈阳召开

会议由中国园艺学会主办 ,中国农业工程学会设施园艺工程专业委员会协办 ,沈阳农业大学园艺系承办 ,于 2 0 0 0年 4月 19日至 2 2日在沈阳农业大学召开。来自我国 13个省、自治区、直辖市的与会代表共 78人 ,会议论文 4 3篇 ,由沈阳农业大学学报专刊发表。经承办单位和与会者努力 ,会议圆满成功。开幕式由中国园艺学会副理事长李树德研究员主持 ,辽宁省科技厅、农业厅、沈阳市副食品局、沈阳农业大学的领导到会祝贺并发表讲话。会议就确定的主题进行了大会发言 ,小组讨论及现场考察。代表们欣喜地看到 ,近 2 0年来我国蔬菜设施生产迅猛发展 …     

Effects of nitric oxide on spontaneous action potentials of guinea-pig left ventricular outflow tract under the conditions of ischemia/reperfusion

AIM: To study the electrophysiological effects of nitric oxide (NO) on the pacemaker cells in guinea-pig left ventricular outflow tract under the condition of ischemia/reperfusion (I/R). METHODS: The spontaneous slow action potentials of guinea-pig left ventricular outflow tract were recorded by conventional intracellular microelectrode technique. The effects of NO donor sodium nitroprusside (SNP) on the spontaneous slow action potentials under normal or I/R condition were investigated. RESULTS: SNP at concentrations of 1, 10 and 100 μmol/L but not 1000 μmol/L significantly increased velocity of diastolic depolarization (VDD) and rate of pacemaker firing (RPF), SNP at concentrations of 1, 10, 100 and 1 000 μmol/L notably increased maximal diastolic potential (MDP), amplitude of action potential (APA) and maximal rate of depolarization (V_max), shortened 50% and 90% of the duration (APD₅₀ and APD₉₀). In ischemia 10 min group, VDD and RPF were significantly decreased, APA and V_max were notably increased, and APD₅₀ and APD₉₀ were markedly lengthened compared with control group. In reperfusion 10 min group, VDD and RPF were significantly increased, MDP and APA were notably decreased, and APD₅₀ and APD₉₀ were markedly shortened compared with I 10 min group. In reperfusin 10 min group, the pacemaker activity was always irregular. In reperfusion 10 min group, the parameters of spontaneous slow action potentials restored to the levels of control group except for VDD and V_max. In 1, 10 and 100 μmol/L SNP+R groups, VDD and RPF were significantly increased than in ischemia 10 min group. In 1, 10, 100 and 1 000 μmol/L SNP+R groups, APA, APD₅₀ and APD₉₀ were restored to the levels of control group. CONCLUSION: SNP significantly increases the spontaneous activity of left ventricular outflow tract, and relieves the effects of I/R on the spontaneous slow action potential markedly.     

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.     

Effect of diazoxide postconditioning on cardiac function and mitochondrial cardiolipin in isolated rat heart

AIM: To investigate the effect of diazoxide (D) postconditioning on Cardiac function and mitochondrial cardiolipin in isolated rat heart and to explore the protective effect of ATP sensitive potassium channel on diazo-xide postconditioning myocardium. METHODS: The myocardial ischemia/reperfusion injury model in isolated rat hearts was established by Langendorff apparatus. The isolated rat hearts were randomized into 4 groups (n=8): control group (control), myocardial ischemia/reperfusion injury group (I/R), diazoxide postconditioning group (I/R+D), 5- hydroxy decanoic acid (5-HD) plus diazoxide postconditioning group (I/R+5-HD+D). The hearts in each group were started with 20 min perfusion for equilibration. The hearts in control group perfused for 70 min; The hearts in I/R group was global ischemia for 40 min after ischemia reperfusion at 4 ℃ ST. Thomas cardioplegia, then reperfusion for 30 min; The hearts in I/R+D group were treated with diazoxide (50 μmol/L) in K-H perfusion for 5 min after global ischemia for 40 min, then reperfusion for 25 min; The hearts in I/R+5-HD+D group were treated with 5-HD (100 μmol/L) in K-H perfusion for 5 min before diazoxide postconditioning, then reperfusion for 20 min. The heart rate, coronary outflow volume, heart function, myocardial enzymes and myocardial mitochondrial cardiolipin at the end of perfusion in each group were determined. RESULTS: Compared with control group and I/R+D group, the heart rate, the concentration of heart phospholipid and the coronary outflow volume were reduced, the heart function was significantly impaired the contents of myocardial enzymes were increased in I/R group. However, no significant difference between I/R group and I/R+5-HD+D group was observed. CONCLUSION: The diazoxide postconditioning protects the myocardium by increasing mitochondrial cardiolipin content, reducing the release of myocardial enzymes, improving heart function and reducing myocardial reperfusion injury. The myocardial protective effect of diazoxide is completely blocked by 5- hydroxy decanoic acid.     

Proteomic study of myocardial mitochondria with ischemia/reperfusion injury and pinacidil postconditioning in isolated rat hearts

AIM: To investigate the protective effect of pinacidil postconditioning on rat myocardium suffering ischemia/reperfusion injury by mitochondrial proteomics. METHODS: Langendorff apparatus was used to establish the model of myocardial ischemia/reperfusion injury. Sprague-Dawley rats were randomly divided into 2 groups: pinacidil postconditioning group (Pina group) and ischemia/reperfusion injury group (I/R group). After 20 min of perfusion with K-H solution, the perfusion was suspended for 40-min (global ischemia) follow by 60 min of reperfusion in I/R group. In Pina group at the end of 40 min global ischemia, the isolated hearts were perfused with K-H solution containing pinacidil (50 μmol/L) for 2 min followed 58-min perfusion with regular K-H solution. Total proteins extracted from the mitochondria were applied to the two-dimensional gel electrophoresis (2-DE). The differentially expressed protein spots over 2 times were evaluated by a software. Then they were subjected to in-gel digestion, and analyzed by spectrometry. RESULTS: The expression levels of NDUFA10, NDUFS2 and NDUFV2 were elevated but those of IDHA and ECH1 were decreased in Pina group compared with I/R group. Interestingly, 2 spots in the 2-DE map were identified as ATPase subunit δ. The expression levels of one spot was elevated, while the other was decreased. CONCLUSION: Pinacidil postconditioning may decrease the degree of increased expression levels of NDUFA10, NDUFS2 and NDUFV2, promote the expression of IDHA and ECH1, and induce the phosphorylation of ATPase subunit δ, which may be related to the protective mechanism of pinacidil postconditioning.     

Role of ATP-sensitive potassium channels in inhibitory effect of hydrogen sulfide on high glucose-induced injury in H9c2 cardiac cells

AIM: To investigate the roles of ATP-sensitive potassium (K_ATP) channels in high glucose-induced cardiac injury and the inhibitory effect of hydrogen sulfide (H₂S) on the cardiomyocyte injury. METHODS: The expression level of K_ATP channel protein was tested by Western blot. The cell viability was measured by CCK-8 assay. The number of apoptotic cells was observed by Hoechst 33258 nuclear staining. Mitochondrial membrane potential (MMP) was examined by JC-1 staining. RESULTS: After the H9c2 cells were treated with 35 mmol/L glucose (high glucose, HG) for 1~24 h, the protein level of K_ATP channel was significantly reduced at 6 h, 9 h, 12 h and 24 h, reaching the minimum level at 12 h and 24 h. Pretreatment of the cells with 400 μmol/L NaHS (a donor of H₂S) prior to exposure to HG for 12 h considerably blocked the down-regulation of K_ATP channels induced by HG. Pretreatment of the cells with 100 μmol/L mitochondrial K_ATP channel opener diazoxide, 50 μmol/L non-selective K_ATP channel opener pinacidil or NaHS obviously inhibited HG-induced injuries, leading to an increase in the cell viability, and decreases in the number of apoptotic cells and the MMP loss. Pretreatment with 100 μmol/L mitochondrial K_ATP channel antagonist 5-hydroxydecanoic acid or 1 mmol/L non-selective K_ATP channel antagonist glibenclamide attenuated the above cardioprotective effects of NaHS. CONCLUSION: K_ATP channels mediate the inhibitory effect of H₂S on HG-induced cardiac injury.     

Role of ATP-sensitive potassium channels in inhibitory effect of hydrogen sulfide on high glucose-induced inflammation mediated by necroptosis in H9c2 cardiac cells

AIM: To investigate the role of ATP-sensitive potassium (K_ATP) channels in the inhibitory effect of hydrogen sulfide (H₂S) on high glucose(HG)-induced inflammation mediated by necroptosis in H9c2 cardiac cells.METHODS: The expression levels of receptor-interacting protein 3 (RIP3; an indicator of necroptosis) and cyclooxyge-nase-2 (COX-2) were determined by Western blot. The levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected by ELISA.RESULTS: After H9c2 cardiac cells were treated with 35 mmol/L glucose (HG) for 24 h, the expression of RIP3 was significantly increased. Pre-treatment of the cells with 100 μmol/L diazoxide (DZ; a K_ATP channel opener) or 400 μmol/L NaHS (a donor of H₂S) for 30 min considerably blocked the up-regulation of RIP3 induced by HG. Moreover, pre-treatment of the cells with 100 μmol/L 5-hydroxydecanoic acid (5-HD; a K_ATP channel blocker) attenuated the inhibitory effect of NaHS on HG-induced up-regulation of RIP3. On the other hand, co-treatment of the cells with 100 μmol/L necrostatin-1 (a specific inhibitor of necroptosis) or pre-treatment of the cells with 100 μmol/L DZ or 400 μmol/L NaHS attenuated HG-induced inflammatory responses, evidenced by decreases in the expression of COX-2 and secretion levels of IL-1β and TNF-α. However, pre-treatment of the cells with 100 μmol/L 5-HD significantly attenuated the above anti-inflammatory effects of NaHS.CONCLUSION: K_ATP channels play an important role in the inhibitory effect of H₂S on HG-induced inflammation mediated by necroptosis in H9c2 cardiac cells.     

Effects of 11, 12-EET and ischemic preconditioning on phosphorylated ERK and p38 MAPK during ischemia and reperfusion in rat myocardium

AIM: In order to study the relationship between the ERK and p38 MAPK activation and the protection of 11, 12-epoxyeicosatrienoic acid (11, 12-EET) and ischemia preconditioning (IP), the effects of 11, 12-EET and ischemic preconditioning on phosphorylated ERK and p38 MAPK during ischemia and reperfusion in rat myocardium were examined. METHODS: The rat heart was subjected to ischemia for 5 min by ligating the left anterior descending coronary artery followed by reperfusion for 5 min (two times) to undergo ischemia preconditioning. The rats were divided into 5 groups: (1) control; (2) sham group; (3) ischemia/reperfusion (I/R) group, in which the rat heart suffered from 60 min ischemia followed by 30 min reperfusion; (4) IP plus I/R group; (5) EET plus I/R group, in which 6.28×10^-8 mol/L 11, 12-EET was injected intravenously 20 min before I/R. The heart function was examined, and phosphorylated ERK and p38 MAPK were detected by Western blot. RESULTS: At 30 min reperfusion, +dp/dt_max, -dp/dt_max and LVDP decreased significantly in I/R group compared with sham group, IP plus I/R group and EET plus I/R group; Phosphorylated ERK1/2 level was higher in I/R group than sham group, but was lower in I/R group than IP plus I/R group and EET plus I/R group; Phosphorylated p38 MAPK level was lower in control, sham, IP plus I/R and EET plus I/R group than I/R group. CONCLUSION: 11,12-EET protects rat heart against ischemia/reperfusion injury, the mechanism may be related to activation of ERK1/2 and inhibition of p38 MAPK.     

Effect of ischemic post-conditioning on myocardial mitochondrial function in isolated rat heart

AIM: To investigate the protective effect of ischemic post-conditioning on isolated rat myocardial mitochondrial function during ischemia/reperfusion, and to study the role of mitochondrial ATP-sensitive potassium channel (mitoK_ATP) in myocardial protection. METHODS: Sprague-Dawley male rats were randomized into 4 groups (n=8 in each group): control group (C), model group (M), ischemic post-conditioning group (IPO) and 5-hydroxydecanoate plus IPO group (5-HD+IPO). The hearts isolated from the SD rats were mounted on a Langendorff apparatus and started with a 20-minute perfusion for equilibration. In C group, the hearts went on perfusion for another 70 min after equilibration. In M group, 4 ℃ St. Thomas cardioplegic solution was administered prior to ischemia, followed by ischemia for 40-minute, and reperfusion for another 30 min. In IPO group, the hearts underwent 40-minute global ischemia after equilibration, then perfusion for 10 s and ischemia for another 10 s. The procedure was repeated 6 times before 28-minute reperfusion. In 5-HD+IPO group, the hearts were perfused with 5-HD (100 μmol/L in K-H solution) and treated as that in IPO group, then reperfusion for 23 min. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and respiratory function of myocardial mitochondria were measured at the ends of equilibration and reperfusion. RESULTS: (1) Compared with the data collected at the end of equilibrium, the MMP was obviously decreased at the end of reperfusion in all groups, The highest in C group. MMP in 5-HD+IPO group was markedly higher than that in IPO group and M group. MMP in IPO group was higher than that in M group. (2) In contrast to that at the end of equilibrium, ROS was obviously increased at the end of reperfusion in all groups. However, ROS was observably higher in M group than that in the other 3 groups, and ROS in 5-HD+IPO group was markedly higher than that in IPO group and C group. ROS in IPO group was higher than that in C group. (3) The respiratory function of mitochondria was obviously injured at the end of reperfusion in all groups. The arrangement of the mitochondrial respiratory function from the best to the worse was C group > IPO group > 5-HD+IPO group > M group. CONCLUSION: Ischemic post-conditioning attenuates myocardial reperfusion injury by maintaining the stability of MMP, decreasing the generation of ROS and preserving the respiratory chain function of mitochondria. The mitoK_ATP antagonist 5-HD can not completely block the myocardial protective effect of ischemic post-conditioning. Myocardial protective effect of ischemic post-conditioning may achieve by activating mitoK_ATP, meanwhile the other factors may also take part in the myocardial protective processes.     

Effects of cardiac remodeling on atrial arrhythmogenesis in aged rabbit left atrium

AIM: To investigate the effects of myocardial remodeling of aged left atrium (LA) on atrial arrhythmogenesis in rabbits.METHODS: The male New Zealand rabbits were divided into young LA and aged LA groups. By observing the changes of monophasic action potential (MAP) and burst-pacing in LA of the rabbits in vivo, the main cardioelectrophysiological parameters such as resting membrane potential (RMP), action potential amplitude (APA), ma-ximum rise veloctiy of action potential (dv/dt_max), plateau potential and action potential duration at 30%, 50% and 90% (APD₃₀, APD₅₀ and APD₉₀), as well as the inducibility and duration of atrial arrhythmias were recorded. L-type calcium current (I_Ca,L) was analyzed via whole-cell patch-clamp technique in enzymatically dissociated single rabbit LA myocytes. The myocardial collagen content was quantified after Masson staining, and the ultrastructure of the LA cells was observed under scanning electron microscope. The expression of Cav1.2 in LA tissue of the 2 groups was detected by Western blot.RESULTS: Compared with young LA group, dv/dt_max and plateau potential were significantly decreased, APD₃₀ and APD₅₀ were shortened, and APD₉₀ was notably prolongated in aged LA group (P<0.01). The inducibility or duration of atrial arrhythmias was severely increased or prolongated in aged LA group (P<0.01). With voltage clamp model, the density of I_Ca,L in aged LA group was significantly decreased, and current-voltage curve was notably moved upward compared with young LA group. When the clamp potential was +20 mV, the density of I_Ca,L was notably modified from (11.72±1.39) pA/pF in young LA group to (6.08±0.98) pA/pF in aged LA group (P<0.01). Compared with young LA group, the protein level of collagen was significantly increased (P<0.01), and the arrange of atrial myocytes was irregular in LA of rabbits in aged LA group. The atrial myocytes of the LA wall in aged LA group exhibited abnormal ultrastructural alterations, such as karyopyknosis, irregular and swelling mitochondria with the presence of vacuoles, and mild and severe sarcomere degeneration. Compared with those in LA tissues of young rabbits, the expression levels of Cav1.2 in the LA tissues of aged rabbits were severely reduced (P<0.01), and had a significant positive correlation with the reduction of I_Ca,L (r=0.83, P<0.01).CONCLUSION: The pathophysiological characteristics of aged LA are significantly altered, and might contribute to vulnerability and susceptibility of occurrence of atrial fibillation in aged rabbits. The mechanisms might completely attribute to the notable reduction of I_Ca,L, abnormal alterations of ultrastructures and obvious decrease in the expression of Cav1.2 in the aged LA of aged rabbits.     

Postconditioning of zacopride depresses ischemia/reperfusion-induced arrhythmias in rats

ATM: To investigate the effects of postconditioning of zacopride, a specific agonist of inwardly rectifying potassium channel (K_ir), on ischemia/reperfusion-induced arrhythmias and the involved electrophysiological mechanisms. METHODS: Langendorff-perfused SD rat hearts or anesthetized rats were subjected to coronary artery occlusion for 15 min followed by 15 min of reperfusion to induce ischemia/reperfusion arrhythmias. Zacopride was applied 3 min before reperfusion. Various arrhythmias were monitored and compared in different groups. The single rat ventricular myocyte was isolated by collagenase digestion. The effects of zacopride on hypoxia/reoxygenation-induced delayed afterdepolarizations (DADs) and ATP-sensitive potassium channel (K_ATP) were observed by the technique of whole-cell patch clamping. RESULTS: Post-conditioning of 0.1~10 μmol/L zacopride significantly prevented the hearts from reperfusion arrhythmias. During reperfusion, 0.1 μmol/L zacopride showed the maximum effect, with decreasing the number of premature ventricular beats (PVB), reducing the incidences of ventricular tachycardia (VT) and ventricular fibrillation (VF), and shorte-ning the duration of VT and VF (P<0.01). The postconditioning effects were partly reversed by 1 μmol/L BaCl₂(P<0.01), suggesting that the antiarrhythmic effect of zacopride was mediated by K_ir. In the in vivo study, 1.5~5 μg/kg zacopride had positive effects on reperfusion-induced VT and VF and negative effect on PVB. At the dose of 1.5 μg/kg, zacopride showed the most potent antiarrhythmic effect, which compared favourably with that of a classical antiarrhythmic agent, lidocaine. Furthermore, zacopride significantly inhibited hypoxia/reoxygenation-induced DADs (P<0.01). Zacopride had no effect on K_ATP.CONCLUSION: The inhibitory effect of zacopride on ischemia/reperfusion-induced arrhythmias is mediated by the activation of K_ir. Augmentation of K_ir cuvrent, thus diminishing the DADs, might be the critical mechanisms underlying postconditioning of zacopride.     

Changes of intracellular Ca2+ in living brain slices during focal cerebral ischemia/reperfusion

AIM: The purpose of the present study was to detect intracellular Ca²⁺changes in living brain slices during focal cerebral ischemia/reperfusion (I/R) and reveal the role of intracellular Ca²⁺in the cerebral I/R injury. METHODS: The model of focal cerebral I/R was established in rats by reversible inserting a nylon thread, and dynamic change of intracellular Ca²⁺in brain slices was determined using laser confocal imaging system. RESULTS: ① Ca²⁺gradually enhanced with increase in ischemic time in cortex and striatum. ②At1h ischemia/10min reperfusion, Ca²⁺increased significantly in striatum, but Ca²⁺decreased at 3 h reperfusion compared with10min reperfusion. ③ Ca²⁺markedly enhanced at 6 h ischemia compared with1h ischemia, and after 3 h reperfusion Ca²⁺decreased, but was still higher than that in sham-operation group. ④The striatum is more sensitive than cortex to ischemia/reperfusion. CONCLUSION: Ca²⁺overload in the area of cortex and striatum may play an important role in cerebral ischemia/reperfusion injury in rats.     

Estrogen affects reactivity of rat mesenteric artery through ATP-sensitive potassium channel

AIM: To observe the expression of ATP-sensitive potassium (K_ATP) channel mRNA in mesenteric artery smooth muscle of rats with estrogen administration, and to evaluate the role of K_ATP channel in the effects of estrogen on the reactivity of mesenteric artery in rats. METHODS: Forty-eight female Sprague-Dawley rats, weighing (100?10) g, were randomly divided into 3 groups: sham operation (sham) group, ovariectomy (Ovx) group and ovariectomy with estrogen administration (Ovx+E) group. The mRNA expression of K_ATP subunits in mesenteric artery smooth muscle was detected by quantitative real-time PCR. Artery reactivity in the rats was observed by norepinephrine-induced pressor response. RESULTS: Compared with sham group, the mRNA expression of Kir6.1 and SUR2B was significantly decreased in Ovx group (P<0.05), but increased in Ovx+E group (P<0.05). Compared with sham group and Ovx+E group, the pressor response induced by norepinephrine in the rats were enhanced in Ovx group (P<0.05). No significant difference between sham group and Ovx+E group was observed. After administered with glibenclamide (a K_ATP channel blocker), the pressor response induced by norepinephrine was enhanced in sham group and Ovx +E group, and no changes in Ovx group. Meanwhile, no difference among the 3 groups was found. CONCLUSION: Estrogen up-regulates the expression of K_ATP channel subunits, which may be involved in estrogen-reduced pressor response to norepinephrine.     

Riboflavin preconditioning alleviates hepatic ischemia/reperfusion injury in rats

AIM: To explore the protective effect of riboflavin preconditioning on hepatic ischemia/reperfusion injury in rats. METHODS: Twenty-four Sprague-Dawley rats wererandomly divided into 3 groups (n=8): sham group, ischemia/reperfusion (I/R) group and riboflavin preconditioning (R+I/R) group. The rats in sham group and I/R group received a standard chow,while the rats in R+I/R group received a chow supplemented with riboflavin. After 4 weeks, portal vein and hepatic artery supplying the middle and left hepatic lobes were clamped with a traumatic vascular clip for induction of partial hepatic ischemia in the rats in I/R group and R+I/R group. After 1 h of ischemia, 1 h of reperfusion was conducted by removal of the clip. The activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum,the activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in serum and liver were measured. Western blotting was employed to examine the protein expression of heme oxygenase-1(HO-1) in the liver. RESULTS: The results showed that ischemia/reperfusion injury markedly increased the activity of AST and ALT in serum, decreased the activity of SOD, and elevated the level of MDA and the activity of HO-1 in the liver as compared with sham group (P<0.01). The riboflavin pretreatment significantly decreased the activity of AST and ALT in serum, increased the activity of SOD and decreased the levels of MDA in serum and liver as compared with I/R group (P<0.01). In addition, the protein expression of HO-1 and the activity of HO-1 were elevated in R+I/R group (P<0.01). Cytoplasmic vacuolation and swelling of the hepatocytes were observed in I/R group. Treatment with riboflavin markedly alleviated the changes of liver structure. CONCLUSION: Riboflavin preconditioning has protective effect on hepatic ischemia/reperfusion injury. The mechanism may be correlated with enhancing the anti-oxidation and alleviating the reaction of lipid peroxidation.     

《中国木本植物种子》

AIM: To test whether ischemic preconditioning (IPC) delays ischemia-induced electrical uncoupling by activation of mitochondrial ATP-sensitive potassium channels (mitoK_ATP). METHODS: Adult rat hearts perfused on a Langendorff apparatus were subjected to 40 min ischemia followed by 30 min reperfusion. Changes in coupling were monitored by measuring whole-tissue resistance. RESULTS: IPC delayed the onset of uncoupling campared to ischemic control; Blocking mitoK_ATP channels before the IPC protocol abolished the delay of uncoupling. The specific mitoK_ATP channel opener diazoxide mimicked the protective effect of IPC. The delay induced by diazoxide was reduced by 5-HD, L-type Ca²⁺ channel inhibitor verapamil and a free radical scavenger N-(2-mercaptopropionyl)glycine. CONCLUSIONS: IPC delays the onset of cellular electrical uncoupling induced by acute ischemia, in which activation of the mitoK_ATP channels may be involved.     

Effect of inhaled nitric oxide on the gas exchange and hemodynamic of ischemia-reperfusion lung in rabbit model

AIM:To evaluate the effect of pulmonary gas exchang and hemodynamic by inhaled nitric oxide on ischemia-reperfusion(I/R) lung in rabbit model.METHODS:Forty Newzealand rabbits were divided into four groups: group Ⅰ, sham-operated; group Ⅱ, sham-operated with inhaled nitric oxide (NO); group Ⅲ, I/R; group Ⅳ, I/R with Inhaled NO. Pulmonary artery pressure (PA), pulmonary vascular resistance(PVR), arterial oxygen tension(PaO₂), arterial carbon dioxide tension (PaCO₂), alveolar-arterial gradient (A-aDO₂), Shunt fraction (Qs/Qt) expression of CD₁₈, peripheral leukocyte, methemoglobin were continuetly quantitated. RESULTS:At the start of reperfusion inhaled NO significantly improved PaO₂ and decreased PA, PVR,PaCO₂,A-aDO₂,Qs/Qt.CONCLUSION:Inhaled NO ameliorated significantly the early gas exchange and hemodynamic of reperfusion lung.     

Role of K+ channels in attenuation of pulmonary vasoreactivity following chronic hypobaric hypoxia in rats

AIM and METHODS: To determine the role of different K⁺-channels in attenuation of vasoreactivity of intrapulminary artery rings induced by chronic hypoxia. RESULTS: ①Acute hypoxia-induced pulmonary vasoconstriction (HPV) could be significantly attenuated by chronic hypobaric hypoxia for 15 days and for 30 days. ②HPV could be significantly potentiated by ATP-sensitive K⁺-channel (K_ATP) blocker or Ca²⁺-activated K⁺-channel (K_Ca) blocker, and the potentiated scope in chronic hypoxic group was much higher than that observed in control group. ③Delayed rectifier K⁺-channel (K_DR) blocker showed no effect on HPV in both control group and chronic hypoxic group. CONCLUSION: Both K_ATP and K_Ca play an important modulating role in HPV and its potentiation may be a critical mechanism for the attenuated vasoreactivity to acute hypoxia following chronic hypobaric hypoxia.     

Roles of PI3K/Akt and JAK2/STAT3 signaling pathways in protection of SO2 against limb ischemia/reperfusion-induced acute lung injury in rats

AIM: To investigate the role of PI3K/Akt and JAK2/STAT3 pathways in the protection of sulfur dioxide (SO₂) against limb ischemia/reperfusion (I/R)-induced acute lung injury (ALI) in rats. METHODS: ALI was induced by limb I/R in the SD rats. Na₂SO₃(0.54 mmol/kg, ip)/NaHSO₃ (0.18 mmol/kg, ip) as SO₂ donor was injected at 20 min before reperfusion. The inhibitors of JAK2/STAT3 and PI3K/Akt pathways, Stattic (3 mg/kg, iv) and LY294002(40 mg/kg, iv), respectively, were injected at 1 h before reperfusion. Peripheral blood and lung tissues were collected for determining the contents of the cytokines, the protein levels of the molecules related to the signaling pathways, apoptosis and histopathologic changes by ELISA, TUNEL and Western blot. RESULTS: Compared with control group, the content of MDA, the activity of MPO, lung coefficient, apoptotic index, cytokine expression, and the protein levels of p-Akt and p-STAT3 in I/R group all increased significantly, and administration of Na₂SO₃/NaHSO₃ attenuated the damage in the lung. Besides, the results of Western blot showed that the rat lung tissues expressed p-STAT3 protein and p-Akt protein. After I/R, the protein levels of p-STAT3 and p-Akt were increased. After using Na₂SO₃/NaHSO₃, p-Akt was increased, but p-STAT3 was decreased (P<0.05). CONCLUSION: Both JAK2/STAT3 and PI3K/Akt pathways are likely involved in the protective effect of SO₂ against limb I/R-induced ALI in rats. The activation of JAK2/STAT3 signaling pathway increases I/R injury. Reversely, the activation of PI3K/Akt signaling pathway reduces I/R injury. Besides, JAK2/STAT3 and PI3K/Akt signaling pathways may have crosstalk during I/R-induced ALI and JAK2/STAT3 pathway may have an impact on the P13K/Akt pathway.     

Effect of preconditioning with pioglitazone on ischemia reperfusion/hypoxia reoxygenation-induced mitochondrial structure and membrane potential in rats

AIM: To observe the effect of preconditioning with pioglitazone on ischemia reperfusion/hypoxia reoxygenation-induced mitochondrial ultramicro-structure and membrane potential in rats. METHODS: Sprague-Dawley rats were randomly divided into four groups: sham-operated (SO) group, ischemia reperfusion (IR) group, pioglitazone preconditioning group (Pio-P) and 5-HD+pioglitazone (5-HD+Pio) group. Apart from the SO group, IR, Pio-P and 5-HD+Pio groups were subjected to 30 min ischemia and 4 h reperfusion. The heart was quickly removed for observing the structure of mitochondria and measurement of the apoptosis index (AI) by TUNEL. Primary cultured cardiomyocytes of Sprague-Dawley rats were divided into control, hypoxic reoxygenation (HR) and different concentrations of Pio-P group. JC-1 staining flowcytometry was adopted to examine mitochondrial membrane potential (ΔΨm). RESULTS: The injury of mitochondrial structure in IR group was severer than that in Pio-P group, while the difference between 5-HD+Pio group and IR group was not evident. Flameng score in Pio-P group(1.62±0.60) was significantly lower than that in IR group (2.75±1.09), P<0.01. AI in Pio-P group (28.19%±4.93%) was lower than that in IR group (55.44%±6.63%),P<0.05. The rates of low ΔΨm cells in (5 μmol/L,10 μmol/L and 15 μmol/L) Pio-P group were (45.89±3.63)%, (17.13±1.37)% and (18.43±2.44)%, significantly lower than that in HR group (56.52%±2.87%),P<0.05, while the difference between 10 μmol/L group and 15 μmol/L group was not significant (P>0.05). CONCLUSION: Pioglitazone protects the heart from ischemia reperfusion/ hypoxia reoxygenation injury evidenced by improving mitochondrial ultrastructure and lessening the loss of mitochondrial membrane potential, and decreasing apoptosis. The cardioprotective effects can be inhibited by the blocker of mitochondrial ATP-sensitive potassium channels.