Protective effect of Jumi extraction on hearts of ischemia-reperfusion injury in rat

AIM: To examine the effect of Jumi (JM) extraction on the contraction of hearts and its cardiac protection against ischemia-reperfusion injury.METHODS: Cardiac contractility and infarct area were analyzed by the Langendorff method in isolated rat hearts.RESULTS: (1) After perfusion with JM extraction (0.5,1.0,2.0 g/L),LVDP,±dp/dtmax and coronary flow were enhanced.(2) JM extraction increased myocardium nitric oxide synthase (NOS) activity and nitric oxide (NO) content in a concentration-dependent manner.(3) Preconditioning or postconditioning of the heart with JM extraction (0.5 g/L),both provided cardioprotection as evidence by improving postischemic ventricular functional recovery and reduced myocardial infarct size.Preperfusion of the hearts with L-NAME (a NOS inhibitor) abolished the cardioprotection induced by JM extraction preconditioning or postconditioning.CONCLUSION: The results demonstrate that JM extraction has positive effect in isolated rat hearts,and it can protect rat heart against ischemia-reperfusion injury through a NO-dependent pathway.     

COX-2 inhibitor protects rat heart against oxidative stress through a pathway independent of cyclooxygenase

AIM: To investigate whether nimesulide ［a selective cyclooxygenase 2 (COX-2) inhibitor］ and piroxicam (an inhibitor of COX-1) protect the rat hearts against oxidative stress induced by hydrogen peroxide,superoxide anion or hydroxyl free radical.METHODS: Cardiac contractility,lactate dehydrogenase (LDH) and malondialdehyde (MDA) were analyzed by the Langendorff method in isolated rat hearts.Production of 6-Keto-PGF1α,a marker of COX activity,was measured in isolated rat hearts.RESULTS: Rat hearts were exposed to hydrogen peroxide (H₂O₂),pyrogallol (which produced superoxide anion) or Vit C+Fe2+ (which produced hydroxyl free radical) for 10 min followed by reperfusion for 30 min.H₂O₂ decreased cardiac contractility and increased LDH release,which was inhibited by nimesulide (3 mg/kg) ［LVDP 72%±10% vs 61%±11%,LDH （5.5±2.5）U/L vs （8.0±2.1）U/L,P<0.05］.Piroxicam (3 mg/kg) increased systolic function (LVDP 73%±10% vs 61%±11%,P<0.05),but exacerbated diastolic function ［LVEDP （29.00±5.61）mmHg vs （23.16±3.57） mmHg,P<0.01］ in H₂O₂ treated rat hearts.Nimesulide also protected rat hearts against superoxide anion and hydroxyl free radical injury.Nimesulide and piroxicam had no effect on the content of 6-Keto-PGF_1α in rat hearts.Mitochondrial ATP sensitive potassium channel (mitoK_ATP) inhibitor 5-HD blocked the improvement of contractility (LVDP and ±dp/dt_max) induced by nimesulide in H₂O₂ treated rat hearts (53%±12% vs 69%±3%,58%±11% vs 72%±7% and 37%±8% vs 51%±4% respectively,P<0.01).CONCLUSION: The results suggests that COX-2 inhibitor nimesulide can protect rat hearts against oxidative injury.The protection is independent of COX activity.Activation of mitoK_ATP may be involved in nimsulide-induced cardioprotection in rat hearts.     

Effect of glycine on cardiac injury induced by hypoxia-reoxygenation in isolated rat heart

AIM:To observe the effects of glycine on hypoxia-reoxygenation (H/R)-induced myocardial dysfunction, and to further clarify the protection of glycine (GLY) against myocardial ischemia/reperfusion injury and its mechanism. METHODS:A cardiac H/R model was established using a Langendorff isolated heart preparation. The left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), the maximum rising and dropping rates of left ventricular pressure (dp/dtmax and dp/dtmin) were observed. The coronary effluents at different time points were collected respectively to detect the concentration of superoxide dismutase (SOD) and malondialdehyde (MDA). RESULTS: The indexes of cardiac functions in H/R group were lower than those in other groups. After H/R, the indexes in GLY plus H/R group were higher than those in H/R group. Glycine inverted the effects of the decrease in SOD and the increase in MDA concentrations induced by H/R. CONCLUSION:Glycine ameliorates the cardiac functions under the condition of hypoxia-reoxygenation injury in isolated rat hearts. The mechanisms may be related to suppressing lipid peroxidation.     

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.     

Protection of maFGF against anoxia/reperfusion injury in isolated rat hearts

AIM: To investigate the protective effects and mechanisms of modified acidic fibroblast growth factor (maFGF) in anoxic reperfusion of rat hearts. METHODS: Using Langendorff apparatus, we established the model of anoxia/reperfusion of isolated hearts to compare the protective effects of maFGF and acidic fibroblast growth factor (aFGF). The changes of left ventricle development pressure (LVDP) and maximal rates of rise of ventricular pressure(dp/dtmax), maximal rates of decline of ventricular pressure (dp/dtmin) were determined, changes of LDH and MDA levels，SOD activity in efflux from coronary artery were also detected at different time point. RESULTS: Pretreatment with maFGF and aFGF produced a similar protective effect on myocardium during anoxia /reperfusion, including promoting obviously heart functional recovery after myocardial anoxia/reperfusion and reversing changes of LDH, MDA contents and SOD activity induced by anoxic/reperfusion. CONCLUSION: maFGF has a protective effect on anoxia/reperfusion heart, and the mechanism of this effect may be related to suppression of lipid peroxidation.     

Protection of Glycyl-L-Glutamine against myocardial ischemia-reperfusion injury in the isolated rat heart

AIM: To study the protection of Glycyl-L-Glutamine(Gly-Gln) against myocardial ischemia/reperfusion(I/R) injury in the isolated rat heart.METHODS: A model of myocardial ischemia-reperfusion injury was established with a Langendorff apparatus. Thirty male SD rats were randomly divided into four groups: control group, Gly-Gln group, I/R group and I/R+Gly-Gln group. Both I/R and I/R+Gly-Gln group were pre-perfused for 30 min, followed by 20 min ischemia and 40 min reperfusion. During reperfusion I/R+Gly-Gln group was perfused with Gly-Gln perfusate. Control group was kept perfused for 90 min. Gly-Gln group Gly-Gln perfusate was also kept perfused for 90 min. The left ventricular end-diastolic pressure(LVEDP), left ventricular developed pressure (LVDP), ±dp/dtmax, heart rate (HR), monophasic action potentials(MAP) was measured during perfusion. The coronary effluent fluid was collected at different certain times. The activities of lactic dehydrogenase (LDH) and creatine kinase(CK) were determined.RESULTS: The isolated rat heart function decreased severely after 20 min ischemia and 40 min reperfusion(I/R): the LVEDP increased and the LVDP, ±dp/dtmax decreased. But the LVEDP decreased and the LVDP, ±dp/dtmax increased in I/R+Gly-Gln group compared with I/R group. Moreover, the activities of LDH and CK in the coronary effluent fluid decreased remarkably in I/R+Gly-Gln group compared with I/R group.CONCLUSION: Gly-Gln can play a protective role against myocardial I/R injury in isolated rat hearts via maintaining the left ventricular function and decreasing the release of LDH and CK.     

Role of mitochondrial calcium uniporter in hypoxic preconditioning

AIM: To investigate the role of mitochondrial calcium uniporter (MCU) in the cardioprotection by hypoxic preconditioning (HPC) and its relationship to mitochondrial permeability transition pore (MPTP). METHODS: Intraventricular balloon technique was employed to measure the left ventricular developed pressure (LVDP), the maximum rise/fall rate of left ventricular pressure (±dp/dtmax), and the left ventricular end-diastolic pressure (LVEDP) in Langendorff isolated rat heart. The hypoxia was achieved by ligation of left anterior coronary artery for 30 min followed by release of ligation for 120 min as reoxygenation. Hypoxic preconditioning was set as two episodes of 5 min global hypoxia and 5 min reoxygenation. RESULTS: Both HPC and treatment with ruthenium red (5 μmol/L) during the first 10 min reoxygenation improved recovery of LVDP, ±dp/dtmax and decreased LVEDP, which was associated with reduced infarct size and lactate dyhydrogenase release. These protective effects were attenuated by treatment with spermine (20 μmol/L) during the first 10 min reoxygenation. Administration of cyclosporin A (0.2 μmol/L) during the last 5 min of hypoxia period and first 15 min of reoxygenation period reduced the injury effect by spermine. CONCLUSION: These results indicate that inhibition of MCU is involved in the cardioprotection of HPC via inhibiting MPTP.     

Dendranthema morifolium attenuated the reduction of contraction of isolated heart and cardiomyocytes induced by ischemia/reperfusion

AIM: To investigate the effect of Dendranthema morifolium (Ramat) Tzvel (DM) on isolated rat heart and ventricular myocytes during ischemia/anoxia and reperfusion/reoxygenation.METHODS: The Langendorff perfused rat hearts were used to measure intraventricular pressure and coronary flow. The cell contraction and intracellular calcium transient in enzymatically isolated ventricular myocytes were determined. RESULTS: (1) DM (0.5 g/L) significantly attenuated the inhibitory effects induced by ischemia/reperfusion on left ventricular developed pressure (LVDP), ±dp/dt_max, coronary flow and LVDP×HR, meanwhile increased the content of SOD and decreased the content of MDA in the myocardium; (2) DM (0.5 g/L) attenuated the inhibitory effects of anoxia and reoxygenation on i transient and cell contraction in isolated ventricular myocytes. CONCLUSION: DM attenuated the effects on contractility and intracellular calcium induced by ischemia/anoxia and reperfusion/reoxygenation in the isolated rat heart and the ventricular myocytes. The mechanism might be related to increase in SOD activity and maintaining [Ca]i homeostasis.     

Alterations of phospholamban expression and cardiac sarcoplasmic reticulum Ca2+-ATPase activity in diabetic rats

AIM:To investigate the alterations of phospholamban (PLB) expression and cardiac sarcoplasmic reticulum (SR) Ca2+-ATPase activity,and the change of cardiac function in rats with diabetes mellitus (DM).METHODS: The diabetes mellitus in male Wistar rats was induced by intraperitoneal injection of streptozotocin.The levels of PLB mRNA and PLB protein,the activity of SR Ca2+-ATPase and the left ventricular hemodynamics parameters were measured 4　weeks,6 weeks and 8 weeks after DM was induced in rats,while the normal rats served as control group.RESULTS: There was no significant difference in PLB mRNA level and protein level between 4-week-DM rats and normal control rats.6-week-DM rats and 8-week-DM rats had markedly increased PLB mRNA and protein level compared with normal control rats.SR Ca2+-ATPase activity was not significantly changed in 4-week-DM rats compared with normal control rats,and was markedly depressed in 6-week-DM rats and 8-week-DM rats.LVSP,LVEDP and ±dp/dtmax were not significantly changed in 4-week-DM rats compared with normal control rats.In 6-week-DM rats and 8-week-DM rats,LVSP and ±dp/dtmax were decreased,LVEDP was increased compared with normal control rats.CONCLUSION: The elevated levels of PLB mRNA and PLB protein contribute to SR Ca2+-ATPase activity reduction,which leads to cardiac dysfunction in DM rats.     

Expression and significance of thrombospondin-1 in myocardium of type 2 diabetic cardiomyopathy rats

AIM: To investigate the expression and significance of thrombospondin-1 (TSP-1) in left ventricular myocardium of type 2 diabetic cardiomyopathy (DCM).METHODS: The rat model of DCM was established by eating a high-fat diet together with injection of low dose streptozocin (30 mg/kg) intrapertoneally.After 12 weeks,the content of collagen was quantified by Masson staining.The mRNA level of TSP-1 was determined by quantification real-time RT-PCR,while the protein level of TSP-1 was analyzed by Western blotting and immunohistochemistry.RESULTS: Compared with the control group,the content of collagen in the DCM group was increased greatly (11.01±3.05 vs 16.92±3.18,P<0.01).The mRNA and protein expressions of TSP-1 were significantly higher than those in control group (0.0089±0.0034 vs 0.0141±0.0037,P<0.05；96.38±16.80 vs 129.98±16.96,P<0.05).In DCM group,the mRNA and protein expressions of TSP-1 showed significantly positive correlations with the levels of fasting blood glucose and collagen (r=0.762,P<0.01; r=0.717,P<0.05; r=0.735,P<0.01; r=0.750,P<0.01).There was a significantly positive correlation of TSP-1 mRNA level with LVEDP (r=0.658,P<0.05).In contrast,there was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.605,P<0.05; r=-0.694,P<0.05).There was a significantly positive correlation of TSP-1 protein with LVEDP (r=0.716,P<0.05).There was a significantly negative correlation of TSP-1 protein with LVSP and -dp/dtmax (r=-0.633,P<0.05; r=-0.669,P<0.05).CONCLUSION: The increased expression of TSP-1 may play an important role in the development of myocardial interstitial fibrosis in DCM.     

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.     

Effects of spermine on myocardial ischemia/ reperfusion injury in rats

AIM: To observe the effect of exogenous spermine (low concentration) on myocardial ischemia/reperfusion injury in rats.METHODS: 40 Wistar rats were randomly divided into 4 groups: sham- operation group (Sham), ischemic reperfusion group (I/R), spermine group (Sp) and natural saline group (NS). The model of ischemic/reperfusion injury was established by ligating rat coronary artery. In Sp group, spermine (0.5 mmol/L, 2 mL/kg) was injected slowly into rat vein. During the process, we recorded the electrocardiogram and the LV functional parameters, assayed the levels of SOD, LDH, NO and MDA in serum, and examined the ultrastructure of the myocardium. RESULTS: In I/R group, the incidence of arrhythmia was 90%, myocardial ultrastructure was injured seriously, values of LVSP and ±dp/dtmax decreased, levels of LDH, NO and MDA increased while SOD activity decreased (P<0.05 or P<0.01, compared with Sham group). Compared with I/R and NS group, all those indexes in Sp group changed significantly (P<0.05 or P<0.01). CONCLUSION: Exogenous spermine alleviates myocardial ischemia/ reperfusion injury in rats. The mechanism may be related to its antioxidant effect and relieving the injury caused by oxygen free radical.     

Effect of endogenous carbon monoxide on intracellular calcium concentration in focal ischemic cerebral tissue in rats

AIM: To study effect of endogenous carbon monoxide on intracellular calcium concentration and explore the mechanism in brain protection of endogenous CO in focal cerebral ischemia in rats. METHODS: SD rats were divided into three groups randomly, which including hemin, ZnPP group and saline group as control. Respectively saline, hemin, ZnPP were injected intra-peritoneally twelve hours before middle cerebral artery was occluded. Twenty four hours after MCAO model was set up, the concentration of carbon monoxide in blood and intracellular calcium in neural cells was examined. RESULTS: Contrast to saline group, the concentration of CO in blood rose up while intracellular calcium in occluded side decreased in hemin group; the concentration of CO in blood went down while intracellular calcium in occluded side rose up in ZnPP group, there was significant difference among them (P<0.05). Hemin and ZnPP had no effect on intracellular calcium in non-occluded sides (P>0.05). CONCLUSIONS: It may be one of mechanisms on brain protection in ischemic cerebral tissue that carbon monoxide affected intracellular calcium concentration of neural cells by regulating Ca²⁺-K⁺ channel on cell membrane as a messenger gaseous molecular and neurotransmitter.     

Change of Gq-phosphoinositide signaling pathway in left ventricular tissue in rats with chronic heart failure and reverse effect of benazepril on it

AIM: To investigate the changes of Gq-phosphoinositide pathway in left ventricular tissue of rats with chronic heart failure in order to assess the role of this signal pathway in the formation of heart failure. METHODS: Male Sprague-Dawle rats were divided into three groups: control, chronic heart failure and benazepril therapy group. Chronic heart failure was induced with adriamycin. Rats in benazepril group received benazepril 10 mg·kg-1·d-1 and adriamycin at the same time. Hemodynamic measurement was carried out after 4 weeks. The expression of Gα q/11 protein in left ventricle was detected by Western blotting analysis and activity of phospholipase C was measured by the method of hydrolysis of nuclear substrate. RESULTS: Compared with control group, the ±dp/dtmax in chronic heart failure group significantly decreased, and protein Gα q/11 expression, basic and stimulated phospholipase C activity significantly increased (P<0.01). The ±dp/dtmax in benazepril group was significantly lower than that in control but obviously higher than that in chronic heart failure group (P<0.05). Gα q/11 expression, basic and stimulated phospholipase C activity in benazepril group were significantly higher than those in control but obviously lower than those in heart failure group (P<0.01). CONCLUSION: Gq-phosphoinositide signaling pathway may play a role in the formation of chronic heart failure. Benazepril partialy attenuates the activation of phosphoinositide signaling pathway.     

Effects of halothane and sevoflurane on the function,metabolism and Ca2＋-ATPase activity of ischemic myocardium

AIM: To study the effects of 1. 5 MAC halothane and sevoflurane on ischemic myocardium. METHODS: The isolated rat heart were perfused with halothane and sevoflurane and HR, LVEDP, LVDP, +dp/dt, -dp/dt, coronary flow (CF), the myocardial ATP content and Ca²⁺-ATPase activity were determined before and 10 min and 25 min after ischemia. In the meantime, LVP was recorded during 25 min ischemia. RESULTS: 1. 5MAC sevoflurane significantly increased CF in normal isolated rat hearts. Both halothane and sevoflurane depressed myocardial contractile function, increased normal myocardial energy storage. After 10 min ischemia, the decrease of myocardial ATP content were slowed down by halothane and sevoflurane, especially halothane. During 25 min of ischemia, the onset time of contracture was significantly delayed, and the contracture intensity was alleviated by halothane, but not sevoflurane. CONCLUSION: Halothane has better protective effect on ischemic myocardium than sevoflurane through preventing the decrease of myocardial ATP content and Ca²⁺-ATPase activity during ischemia.     

Effect of pressure phase plane derived τ and K on evaluation of left ventricular diastolic function in isolated rat heart during ischemia/reperfusion

AIM: To analyze and compare the changes of pressure phase plane (PPP) derived τ and K on isolated rat heart during ischemia/reperfusion, and to explore the value of PPP derived τ and K for evaluation of left ventricular diastolic dysfunction. METHODS: LVEDP, -(dp/dt)_max, τ and K were measured and calculated during ischemia/reperfusion in Sprague-Dawley rat hearts. Meanwhile, the level of lactate dehydrogenase (LDH) in the coronary effluent was measured, and the ultrastructure changes in myocardium were observed under electron microscope. RESULTS: Compared with control group, τ increased and K reduced significantly in each ischemic group in a time dependent manner (P<0.05). With prolonged ischemia, τ was even higher and K was even lower (P<0.05). Compared with control group, except ischemia 15 min, LDH in other groups increased significantly at 10 min and 20 min after reperfusion (P<0.05). Compared with ischemia 30 min, LDH of ischemia 45 min and ischemia 60 min were even higher at 10 min and 20 min after reperfusion (P<0.05). With prolonged ischemia, the abnormal changes of the myocardial ultrastructure were observed. CONCLUSION: PPP derived τ and K may be promising indexes for quantitative assessment of left ventricular diastolic function on isolated rat heart during ischemia/reperfusion, and indication of the severity of ischemia/reperfusion injury.     

Role of mitochondrial permeability transition pore in TNFα-induced cardioprotection in isolated rat hearts subjected to hypoxia and reoxygenation

AIM: To investigate whether tumor necrosis factor α (TNFα) pretreatment can inhibit mitochondrial permeability transition pore opening in isolated rat hearts subjected to hypoxia and reoxygenation. METHODS: Isolated perfused rat hearts were subjected to 30 min regional hypoxia (occlusion of left anterior descending artery) and 120 min reoxygenation. The infarct size, lactate dehydrogenase (LDH) release during reoxygenation and ventricular hemodynamic parameters were measured. RESULTS: Pretreatment with TNFα at concentration of 1×104 U/L for 7 min followed by 10 min washout reduced the infarct size and LDH release, and improved the left ventricular performance (left ventricular developed pressure and rate-pressure product) and left ventricular end-diastolic pressure during hypoxia and reoxygenation. Administration of atractyloside (Atr, an opener of mitochondrial permeability transition pore, 20 μmol/L) for 20 min (last 5 min of hypoxia and first 15 min of reoxygenation) and paxilline (Pax, a calcium activated potassium channel antagonist, 1 μmol/L) for 5 min before hypoxia attenuated the reduction of infarct size and LDH release and improved the left ventricular performance induced by TNFα. CONCLUSION: The findings indicate that in the isolated rat heart model, TNFα protects myocardium against hypoxia and reoxygenation injury via inhibiting mitochondrial permeability transition pore opening as well as activating calcium, activated potassium channel.     

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.     

Relationship between expression of heme oxygenase-1 mRNA and pulmonary hypertention induced by hypoxic hypercapnia

AIM: To study the effect of chronic hypoxic hypercapnia on expression of heme oxygenase-1 (HO-1). METHODS: Sprague-Dawley rats were randomly divided into three groups: control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+hemin group(C). HO-1 and HO-1 mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization. RESULTS: ① mPAP and weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were significantly higher in rats of B group than those of A and C group (P<0.01). Differences of mCAP were not significant in three groups(P>0.05). ② Blood CO concentration was significantly higher in rats of B group than that of A group (P<0.01), it was much higher in C group than that of B group(P<0.01). ③ Light microscopy showed that vessel well area/total area (WA/TA), density of medial smooth muscle cell (SMC) and media thickness of pulmonary arterioles were much higher in rats of B group than those of A and C group (P<0.01). ④ The observation by electron microscopy showed proliferation of medial smooth muscle cells and collageous fibers of pulmonary arterioles in rats of B group, hemin could reverse the changes mentioned above. ⑤ HO-1 and HO-1 mRNA in pulmonary arterioles was significantly higher in rats of B group than those of A group(P<0.01), and they were significantly higher in rats of C group than those of B group (P<0.01). CONCLUSION: Expression of HO-1 mRNA and HO-1 in pulmonary arterioles was enhanced by hypoxic hypercapnia. Hemin partly inhibited pulmonary hypertension and pulmonary vessel remodeling by enhancing the expression of HO-1 mRNA and HO-1.