N-acetylcysteine Improves Cardiac Contractility and Ameliorates Myocardial Injury in a Rat Model of Lung Ischemia and Reperfusion Injury

ObjectivesLung ischemia and reperfusion (I/R) injury is the major complication subsequent to cardiopulmonary bypass surgery and lung transplantation. Lung I/R injury frequently induces cardiac dysfunction leading to significant mortality. So far, the literature on therapeutic interventions in cardiac dysfunction and myocardial injury is still scarce. In this study, we examined the efficacy of N-acetylcysteine (NAC) administration against lung I/R injury–induced cardiac dysfunction.MethodsLung ischemia was established by occluding the left lung hilum for 60 minutes, followed by 2 hours of reperfusion. Studies were performed in 3 groups: sham-operated (same surgical procedure except vessel occlusion; N = 8), lung I/R injury (N = 12), and NAC-administered group (N = 12). The cardiac function was assessed using simultaneous left ventricular (LV) pressure and volume measured via a high-fidelity pressure-volume catheter. Myocardial injury was assessed based on serum creatine kinase muscle brain fraction (CK-MB) and troponin I (cTnI) level, and lung injury based on the degree of protein concentration in lung lavage. We also examined the degrees of myocardial lipid peroxidation and hydroxyl radical production with and without NAC.ResultsDuring lung ischemia, LV stiffness increased with relative intact contractility. After 2 hours of reperfusion, LV contractility decreased with dilated and stiffened ventricle, along with apparent myocardial and lung injury. NAC administration effectively attenuated heart and lung injury, and ameliorated impaired LV contractility and stiffening resulting from lung I/R injury.ConclusionsNAC administration reduced lung I/R-induced increases in myocardial hydroxyl radical production and lipid peroxidation, and ameliorated LV contractility and stiffening.     

二氮嗪后处理对大鼠离体心脏缺血再灌注损伤的影响

目的 评价二氮嗪后处理对大鼠离体心脏缺血再灌注损伤的影响.方法 雄性SD大鼠,体重250～300 g,成功建立Langendorff再灌注模型的64个心脏随机分为4组(n=16):正常对照组(C组)、缺血再灌注组(I/R组)、二氮嗪后处理组(D组)和线粒体ATP敏感性钾通道阻断剂5-羟葵酸+二氮嗪后处理组(5-HD+D组).采用K-H液平衡灌注20 min时,C组继续灌注K-H液70 min;I/R组、D组和5-HD+D组进行心肌缺血40 min,I/R组缺血前灌注4 ℃ ST.Thomas停跳液10 ml/kg;D组再灌注5 min时灌注含50μmol/L二氮嗪的K-H液5 min,然后再灌注20 min;5-HD+D组灌注二氮嗪前灌注含100 μmol/L 5-羟葵酸的K-H液5 min,再灌注20 min.分别于平衡灌注末与再灌注末时取8个心脏,记录心功能指标,然后提取线粒体,测定心肌细胞线粒体膜电位(MMP)、氧自由基(ROS)生成量和呼吸功能指标.结果 各组平衡灌注末时各指标差异无统计学意义(P＞0.05).与C组比较,再灌注末时其余3组心功能和线粒体呼吸功能减退,MMP降低,ROS生成量增加(P＜0.05或0.01);与I/R组和5-HD+D组比较,D组心功能和线粒体呼吸功能改善,MMP升高,ROS水平降低(P＜0.01).结论二氮嗪后处理可减轻大鼠心肌缺血再灌注损伤,其机制与开放线粒体ATP敏感性钾通道而改善线粒体功能有关.     

Augmenter of liver regeneration-mediated mitophagy protects against hepatic ischemia/reperfusion injury

Augmenter of liver regeneration (ALR) is an anti-apoptotic protein found mainly in mitochondria. It protects hepatocytes from ischemia-reperfusion (I/R) injury, but the underlying mechanism is not clear. We found that in rats, delivery of the ALR gene alleviated hepatic I/R injury during orthotopic liver transplantation as evidenced by reduced serum aminotransferase, oxidative stress and apoptosis, and increased expression of autophagy markers. In an in vitro hypoxia/reoxygenation (H/R) model, overexpression of the ALR gene activated autophagy and relieved defective mitophagy via the PINK1/Parkin pathway. Mechanistically, ALR transfection induced the expression of mitofusin 2 (Mfn2) in the H/R model, which led to PINK1 accumulation and mitochondrial translocation of Parkin. Deletion of Mfn2 abolished mitophagy activation induced by ALR transfection, promoted mitochondrial dysfunction, and eventually increased cell apoptosis. Mfn2 administration prevented the inhibition of mitophagy in ALR-knockout (KO) cells, thus attenuated mitochondrial dysfunction and cell apoptosis. In heterozygous ALR-knockout mice treated with a warm I/R injury, marked aggravation of liver injury was associated with mitophagy inhibition and reduction in Mfn2 expression. Taken together, our results confirm that ALR accelerated Parkin translocation and mitophagy via Mfn2, and protected hepatocytes from I/R-induced injury. Our findings provide a novel rationale for the treatment of hepatic I/R injury.     

"Chemical preconditioning" by 3-nitropropionate reduces ischemia-reperfusion injury in cardiac-arrested rat lungs

BACKGROUND: Chemical preconditioning was defined as the induction of resistance to massive disruption of energy metabolism through prior chemical suppression of oxidative phosphorylation, by which phenomena similar to those resulting from increased ischemic tolerance as a result of ischemic preconditioning can be induced. It could be induced by the inhibitor of either mitochondrial complex I or II. We investigated whether or not chemical preconditioning by 3-nitropropionate (an inhibitor of the mitochondrial complex II) can suppress ischemia-reperfusion injury in cardiac-arrested lungs, which will be the major problem in lung transplants donated from non-heart-beating cadavers. METHODS AND RESULTS: In an isolated rat lung perfusion model with fresh rat blood as perfusate, administration of 3-nitropropionate (20 mg/kg) immediately before the induction of cardiac arrest attenuated pulmonary dysfunction during reperfusion after 1 hr postmortem warm ischemia and 1 hr cold preservation. 3-Nitropropionate administration reduced the mitochondrial respiratory functions (state 3 and state 4 respiration, and the respiratory control ratio) before cardiac arrest and kept them at a lower level of activity than when decreased by ischemia alone. 3-Nitropropionate administration also reduced the ATP levels immediately after drug administration. However, 3-nitropropionate did not significantly reduce lipid peroxidation in the lung tissue and mitochondria. CONCLUSIONS: These results demonstrated that chemical preconditioning by 3-nitropropionate administration immediately before cardiac arrest suppressed succinate-related oxidation during postmortem warm ischemia and reduced ischemia-reperfusion injury in cardiac arrested rat lungs.     

Adverse effects of bilateral lower limb ischemia–reperfusion on inducing kidney injuries in rats could be ameliorated by platonin

ObjectivesBilateral lower limb ischemia–reperfusion (I/R) could cause significant oxidative stress, elicit inflammatory response, and subsequently induce kidney injury in animals. We tested the effects of platonin, a potent antioxidant, on mitigating the kidney injury induced by lower limb I/R in rats.MethodsAdult male rats were allocated to receive I/R or I/R plus platonin (100 μg/kg intravenous injection immediately after reperfusion), and denoted as the I/R or the I/R-P group, respectively (n = 10 in each group). Sham groups were run simultaneously. Bilateral lower limb I/R was achieved by applying rubber-band tourniquets high around each thigh for 3 hours, followed by reperfusion for 6 hours. After sacrifice, the level of kidney injury was assayed.ResultsI/R significantly increased the plasma concentrations of blood urea nitrogen (BUN) and creatinine (Cr). However, this effect could be mitigated by platonin, as the plasma concentrations of BUN and Cr of the I/R-P group were significantly lower than those of the I/R group. Moreover, histological findings revealed moderate injury in kidney tissues of the I/R group and mild injury in those of the I/R-P group. In addition, the leukocyte infiltration and myeloperoxidase activity in kidney tissues as well as the renal concentrations of inflammatory molecules (i.e., cyclooxygenase-2/prostaglandin E₂, interleukin-6, and macrophage inflammatory protein-2) and malondialdehyde (i.e., the index of lipid peroxidation) of the I/R group were significantly higher than those of the I/R-P group.ConclusionPlatonin attenuates kidney injury induced by bilateral lower limb I/R in rats.     

Effect of varicocele on sperm function and semen oxidative stress

Study Type – Aetiology (case control) Level of Evidence 3b What’s known on the subject? and What does the study add? Varicocele leads to alterations in sperm DNA integrity even when alterations in semen quality are not yet observed in adolescents. In adults, alterations to sperm DNA are associated to altered sperm morphology, indicating that altered spermatogenesis may be an important cause for the increased sperm DNA fragmentation observed in these men. One other important cause of increased DNA fragmentation is oxidative stress, and we wished to verify if this was the case. The study adds the information that, in the adult varicocele, it is most likely that an altered testicular environment is leading to increased DNA fragmentation and decreased mitochondrial activity and acrosome integrity, because no increase in oxidative stress was observed.

OBJECTIVE

? To assess the effect of varicocele on sperm DNA integrity, mitochondrial activity, lipid peroxidation and acrosome integrity.

PATIENTS AND METHODS

? In all, 30 patients with a clinically diagnosed varicocele of grade II or III and 32 men without a varicocele were evaluated for sperm DNA fragmentation (comet assay), mitochondrial activity (3,3′‐diaminobenzidine assay), lipid peroxidation (malondialdehyde) and acrosome integrity (fluorescent probe labelled peanut agglutinin).

RESULTS

? The varicocele group showed fewer spermatozoa with intact DNA (grade II, P= 0.040), more cells with inactive mitochondria (class III, P= 0.001), fewer cells with active mitochondria (class I, P= 0.005) and fewer spermatozoa with intact acrosomes (P < 0.001). Finally, no significant differences were observed in lipid peroxidation levels.

CONCLUSION

? Men with varicocele showed an increase in sperm DNA fragmentation and a reduction in mitochondrial activity and acrosome integrity. However, lipid peroxidation levels remained unchanged.     

Protective effect of sitagliptin against renal ischemia reperfusion injury in rats

Abstract

This study was designed to investigate the protective effects of sitagliptin on renal damage induced by renal ischemia reperfusion (I/R) in rats. For this, rats were randomly divided into four groups (n?=?8): (1) sham group, in which the rats only underwent right nephrectomy; (2) right nephrectomy and left kidney ischemia (1?h) and reperfusion (24?h) group (I/R); (3) 5?mg/kg sitagliptin administrated group, per-oral once a day for two weeks; (4) 5?mg/kg sitagliptin administrated group, per-oral once a day for two weeks before left kidney I/R (n?=?8). Sitagliptin-treated rats that underwent renal I/R demonstrated significant decrease in the serum urea nitrogen and creatinine and also, lipid peroxidation, total oxidant status and malondialdehyde level in the renal tissue when compared to the renal I/R group. Additionally, reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase and total antioxidative capacity were significantly increased after renal I/R in sitagliptin-treated rats. Our histopathological findings were in accordance with these biochemical results. In sum, in the current study all of our results indicated that sitagliptin treatment ameliorated renal damage induced by renal I/R in rats.     

S-腺苷蛋氨酸对大鼠缺血再灌注肝脏能量代谢的影响

目的研究S-腺苷蛋氨酸(SAM)预处理对大鼠肝脏缺血再灌注损伤线粒体功能的影响。方法54只大鼠按随机数字表法随机均分为对照组、缺血再灌注组(I/R组)和SAM组,SAM组大鼠肝脏在缺血前2h行腹腔注射SAM预处理。3组动物在阻断肝门30min后(对照组仅做分离,不阻断肝门)复流,并于再灌注后0、1和6h抽取下腔静脉血检测ALT及AST,切取肝组织检测线粒体SOD、MDA、ATP及EC,并制备病理切片在电镜下观察线粒体的超微结构。结果再灌注后0、1及6h,I/R组ALT、AST和MDA明显高于对照组(P<0.01),SOD(除0h外)、ATP及EC明显低于对照组(P<0.01);SAM组ALT、AST及MDA(除0h外)明显低于I/R组(P<0.01),SOD(除0h外)、ATP及EC明显高于I/R组(P<0.05,P<0.01)。超微结构观察,I/R组线粒体较对照组有明显的损伤,线粒体数量减少,肿胀明显,嵴模糊不清,基质密度低;而SAM组与I/R组相比损伤程度明显减轻。结论SAM能抑制线粒体脂质过氧化反应,提高ATP的产生,最终提高线粒体的能量代谢水平,有效地减轻肝脏的缺血再灌注损伤。     

Hydrogen-rich saline attenuates neuronal ischemia–reperfusion injury by protecting mitochondrial function in rats

Background

Hydrogen, a popular antioxidant gas, can selectively reduce cytotoxic oxygen radicals and has been found to protect against ischemia–reperfusion (I/R) injury of multiple organs. Acute neuronal death during I/R has been attributed to loss of mitochondrial permeability transition coupled with mitochondrial dysfunction. This study was designed to investigate the potential therapeutic effect of hydrogen-rich saline on neuronal mitochondrial injury from global cerebral I/R in rats.

Materials and methods

We used a four-vessel occlusion model of global cerebral ischemia and reperfusion, with Sprague–Dawley rats. The rats were divided randomly into six groups (n = 90): sham (group S), I/R (group I/R), normal saline (group NS), atractyloside (group A), hydrogen-rich saline (group H), and hydrogen-rich saline + atractyloside (group HA). In groups H and HA, intraperitoneal hydrogen-rich saline (5 mL/kg) was injected immediately after reperfusion, whereas the equal volume of NS was injected in the other four groups. In groups A and HA, atractyloside (15 μL) was intracerebroventricularly injected 10 min before reperfusion, whereas groups NS and H received equal NS. The mitochondrial permeability transition pore opening and mitochondrial membrane potential were measured by spectrophotometry. Cytochrome c protein expression in the mitochondria and cytoplasm was detected by western blot. The hippocampus mitochondria ultrastructure was examined with transmission electron microscope. The histologic damage in hippocampus was assessed by hematoxylin and eosin staining.

Results

Hydrogen-rich saline treatment significantly improved the amount of surviving cells (P < 0.05). Furthermore, hydrogen-rich saline not only reduced tissue damage, the degree of mitochondrial swelling, and the loss of mitochondrial membrane potential but also preserved the mitochondrial cytochrome c content (P < 0.05).

Conclusions

Our study showed that hydrogen-rich saline was able to attenuate neuronal I/R injury, probably by protecting mitochondrial function in rats.     

Effect of apigenin on apoptosis induced by renal ischemia/reperfusion injury in vivo and in vitro

Objectives: This study aims to investigate the effects and molecular mechanisms of apigenin (ApI) on renal ischemia/reperfusion (I/R) injury in vivo and in vitro.

Methods: In vivo, the left renal artery was clamped for 45?min and the right kidney was removed to study renal I/R injury on Sprague-Dawley (SD) rats. ApI was injected at 60?min before renal ischemia. In vitro, renal tubular epithelial cells (HK-2) were pretreated with or without ApI (20 uM) for 60?min and then treated with hypoxia/reoxygenation (H/R). Renal function, histology, cells apoptosis, and cell viability were tested. Furthermore, the potential molecular mechanisms were assessed.

Results: ApI pretreatment could significantly alleviated the renal function and the pathological damage as well as cells apoptosis after I/R injury. Meanwhile, ApI treatment protects H/R induced HK-2 cell apoptosis in vitro. The results of Western blot showed that ApI significantly increased the expressions of B-cell lymphoma 2 (Bcl-2) and phosphor-AKt (p-AKt), Phosphoinositide 3-kinase (PI3K), while down-regulated the expressions of Caspase3 and Bax induced by H/R injury.

Conclusions: ApI pretreatment can protect renal function against I/R injury and prevent renal tubular cells from apoptosis in vivo and in vitro which might through PI3K/Akt mediated mitochondria-dependent apoptosis signaling pathway.     

Salidroside Inhibits Ischemia/Reperfusion-Induced Myocardial Apoptosis by Targeting Mir-378a-3p Via the Igf1r/Pi3k/Akt Signaling Pathway

BackgroundThe present study aimed to investigate the protective effects and mechanism of salidroside (SAL) on hypoxia/reoxygenation (H/R)-induced cardiomyocyte apoptosis and myocardial ischemia/reperfusion (I/R) injury.MethodsWe set up an H/R H9c2 cell model in vitro and an I/R rat model in vivo. Cell viability, apoptosis and histopathologic evaluation were conducted.ResultsThe cell viability of H/R-induced cardiomyocytes was increased by pretreatment of SAL, whereas the release of lactate dehydrogenase, reactive oxygen species production, and apoptosis were decreased accompanied with reduced Cleaved-caspase-3 and Bax, and increased Bcl-2 expressions. The SAL restored mitochondrial membrane potential both in vitro and in vivo, and improved electrocardiographic abnormality, and attenuated myocardial apoptosis and injury in I/R-induced rats. The transfection of miR-378a-3p inhibitor counteracted the effects of SAL-induced increase of cell viability and decrease of cell apoptosis and mitochondrial membrane potential. SAL reduced the expression of insulin-like growth factor 1 receptor (IGF1R), and increased the expressions of PI3K and Akt, however, these alterations were blocked by miR-378a-3p inhibitor.ConclusionsmiR-378a-3p might participate in the protective effect of SAL in I/R-induced myocardial apoptosis via the IGF1R/PI3K/AKT signaling pathway.     

The protective effect of nesfatin-1 against renal ischemia–reperfusion injury in rats

Abstract

Introduction: The pathogenetic mechanisms underlying ischemia-reperfusion (I/R) injury involve oxidative stress, inflammation and apoptosis. Nesfatin-1, a novel peptide, has been reported to possess antioxidant, anti-inflammatory and anti-apoptic properties. The study was to examine the potential protective effects of nesfatin-1 on renal I/R injury. Materials and methods: I/R model was induced by placing a clamp across left renal artery for 45?min followed by 24?h reperfusion, along with a contralateral nephrectom. Twenty-four rats divided into three groups: sham-operated group, vehicle-treated I/R and nesfatin-1-treated I/R. Nesfatin-1 was intraperitoneally injected 30?min before renal ischemia. We harvested serum and kidneys at 24?h after reperfusion. Renal function and histological changes were assessed. Marker of oxidative stress and cells in kidney were also evaluated. Results: The animals with nesfatin-1 significantly improved renal functional and histologic lesions induced by I/R injury. The malondialdehyde (MDA) level decreased, whereas superoxide dismutase (SOD) and catalase (CAT) activities were significantly increased. Moreover, nesfatin-1-treated rats had a markedly decrease in apoptotic tubular cells, as well as a decrease in caspase-3 activity and an increase in the bcl-2/Bax ratio. Conclusions: This is the first evidence that nesfatin-1 treatment ameliorates acute renal I/R injury by suppressing oxidative stress and cell apoptosis. Therefore, it is promising as a potential therapeutic agent for renal IR injury.     

Cardioprotection afforded by ischemic preconditioning interferes with chronic beta‐blocker treatment

Objectives—The efficacy of ischemic preconditioning of the heart has remained controversial. We investigated whether chronic treatment with beta‐blockers affects the ischemic preconditioning in the isolated rat heart model.

Design—Wistar rats were treated with propranolol (50?mg/kg/day, p.o.) (PRL), with nipradilol (10?mg/kg/day, p.o.) (NPL), or with vehicle, for 4 weeks. Isolated rat hearts were divided into global ischemia hearts (GI, PRL and NPL, each n=6) and ischemic preconditioned hearts (IP, PRL+IP and NPL+IP, each n=6).

Results—Significant differences in left ventricular pressure were observed between the PRL and PRL+IP, and between the NPL and NPL+IP groups. In the NPL group, significant amelioration and preservation of left ventricular peak pressure, coronary flow, reduction of infarct size, and NOx preservation were observed. Lipid peroxidation in the NPL group was significantly reduced before and after global ischemia compared to the GI group.

Conclusions—The effect of ischemic preconditioning was abolished in the hearts of rats following oral treatment of propranolol or nipradilol. However, the administration of nipradilol protected the ischemic and reperfused myocardium, partly due to the prevention of lipid peroxide formation.     

Age-associated differences in the inhibition of mitochondrial permeability transition pore opening by cyclosporine A

Background: Inhibiting mitochondrial permeability transition pore (mPTP) opening is a key protection of the myocardium from ischemia/reperfusion (I/R) injury. Here, we investigated age‐associated differences in the ability of cyclosporine A (CsA) to protect the heart and to modulate mPTP opening during I/R injury in vivo and its opening induced by reactive oxygen species (ROS) in vitro. Methods: Fischer 344 male rats were assigned from their respective age groups, young or old groups, to (1) I/R or (2) I/R+CsA. All animals were subjected to 30 min of ischemia following 120 min of reperfusion to determine myocardial infarct size in vivo. To measure mPTP opening in vivo, left ventricular tissues were collected 10 min after reperfusion and nicotinamide adenine dinucleotide (NAD⁺) levels were measured. In parallel experiments, rat ventricular myocytes were prepared from young and old hearts, loaded with tetramethylrhodamine ethylester and then subjected to oxidative stress in the presence or absence of CsA, and the mPTP opening time was measured using laser scanning confocal microscopy. Results: CsA reduced myocardial infarct size in young I/R rats. Whereas CsA failed to significantly affect myocardial infarct size in old I/R rats, NAD⁺ levels were better preserved in young CsA‐treated rats, but this relative improvement was not observed in old rats. CsA also significantly prolonged the time necessary to induce mPTP opening in young cardiomyocytes, but not in cardiomyocytes isolated from the old rats. Conclusions: mPTP regulation is dysfunctional in the aged myocardium and this could account for loss of cardioprotection with aging.     

Skeletal muscle mitochondrial function is preserved in young patients with chronic renal failure

Patients with chronic renal failure (CRF) show limited exercise tolerance, classically attributed to anemia. However, persistence of abnormally low peak oxygen consumption, even after restoration of hemoglobin concentration with recombinant erythropoietin therapy and studies of muscle bioenergetics, suggests that the problem is located beyond hemoglobin oxygen transport. The present study is designed to assess mitochondrial respiratory chain (MRC) function from skeletal muscle of patients with CRF to determine whether there is impairment in mitochondrial oxidative capacity. We studied six young patients with CRF on regular hemodialysis and erythropoietin therapy and six healthy controls matched by age, sex, anthropometric characteristics, and physical activity. Muscle biopsy of the quadriceps was performed, and mitochondria were isolated. Mitochondrial content was estimated by means of mitochondrial yield and citrate synthase activity. Maximal capacity for oxygen consumption was measured polarographically using complex I, II, III, and IV substrates of the MRC. Individual enzyme activities of MRC complexes I to V were determined spectrophotometrically. Membrane lipid peroxidation was estimated by cis-parinaric fluorescence. Compared with controls, patients with CRF showed preserved mitochondrial content, conserved respiratory activity, intact enzyme activity of MRC complexes, and no increase in lipid peroxidation. We therefore conclude that mitochondrial function is preserved in young patients with CRF. © 2002 by the National Kidney Foundation, Inc.     

Ex vivo Application of Carbon Monoxide in UW Solution Prevents Transplant‐Induced Renal Ischemia/Reperfusion Injury in Pigs

I/R injury is a major deleterious factor of successful kidney transplantation (KTx). Carbon monoxide (CO) is an endogenous gaseous regulatory molecule, and exogenously delivered CO in low concentrations provides potent cytoprotection. This study evaluated efficacies of CO exposure to excised kidney grafts to inhibit I/R injury in the pig KTx model. Porcine kidneys were stored for 48 h in control UW or UW supplemented with CO (CO‐UW) and autotransplanted in a 14‐day follow‐up study. In the control UW group, animal survival was 80% (4/5) with peak serum creatinine levels of 12.0 ± 5.1 mg/dL. CO‐UW showed potent protection, and peak creatinine levels were reduced to 6.9 ± 1.4 mg/dL with 100% (5/5) survival without any noticeable adverse event or abnormal COHb value. Control grafts at 14 days showed significant tubular damages, focal fibrotic changes and numerous infiltrates. The CO‐UW group showed significantly less severe histopathological changes with less TGF‐β and p‐Smad3 expression. Grafts in CO‐UW also showed significantly lower early mRNA levels for proinflammatory cytokines and less lipid peroxidation. CO in UW provides significant protection against renal I/R injury in the porcine KTx model. Ex vivo exposure of kidney grafts to CO during cold storage may therefore be a safe strategy to reduce I/R injury.     

L-ascorbic acid and alpha-tocopherol attenuates liver ischemia-reperfusion induced of cardiac function impairment

Objectives

The Pringle maneuver is a surgical procedure to minimize hemorrhage during hepatectomy, which however, can induce production of reactive oxygen species causing remote organ injury. We sought to study the impact of the Pringle maneuver on cardiac function as well as the protective effects of L-ascorbic acid and α-tocopherol pretreatments.

Methods

Rats were divided into four study groups: L-ascorbic acid (60 mg/kg/d) or α-tocopherol (200 mg/kg/d), and surgical interventions (Sham-operated or liver ischemia-reperfusion [I/R]). Liver ischemia was performed by clamping the hepatic artery and portal vein for 30 minutes, followed by reperfusion by releasing the clamps for 2 hours. Cardiac function was evaluated by a high-fidelity pressure-volume catheter positioned in the left ventricle. Myocardial injury was assessed through plasma creatine kinase-MB (CKMB) and troponin I (cTnI). Cardiac lipid peroxidation and systemic hydroxyl radical levels were assessed by cardiac tissue malondialdehyde and plasma methylguanidine, respectively.

Results

Cardiac function was significantly depressed in the I/R group, where plasma CKMB and cTnI were markedly increased (P < .05). L-ascorbic acid and α-tocopherol pretreatments improved cardiac function and significantly reduced cardiac injury (P < .05). L-ascorbic acid pretreatment demonstrated better heart protection than α-tocopherol, in terms of cTnI and CKMB (P < .05), but no significant difference in terms of cardiac functional improvement.

Conclusions

L-ascorbic acid and α-tocopherol pretreatment 3 days prior to the Pringle maneuver attenuated myocardial injury and protected cardiac function by scavenging hydroxyl radical and reducing lipid peroxidation. L-ascorbic acid demonstrated better protection than α-tocopherol.     

含吡那地尔的心脏保存液对大鼠离体心脏线粒体呼吸功能的影响

目的 探讨含吡那地尔的心脏保存液(HTK液)对大鼠离体心脏线粒体呼吸功能的影响.方法 健康清洁级SD大鼠120只,建立离体心脏Langendorff灌注模型,随机分为5组,HTK组(Ⅰ组)、吡那地尔+HTK液组(Ⅱ组)、吡那地尔+HTK液+5-羟葵酸(5-HD)组(Ⅲ组)、吡那地尔+HTK液+HMR-1098组(Ⅳ组)、吡那地尔+HTK液+HMR-1098+5-HD组(Ⅴ组).K-H液平衡灌注10 min后灌注心脏停搏液:Ⅰ组灌注HTK液;Ⅱ组灌注含吡那地尔0.5 mmol/L的HTK液;Ⅲ组灌注含吡那地尔0.5 mmol/L和5-HD 100μmol/L的HTK液;Ⅳ组灌注含吡那地尔0.5 mmol/L和HMR-1098 100μmol/L的HTK液;Ⅴ组灌注含吡那地尔0.5 mmol/L、5-HD 100μmol/L和HMR-1098 100 μmol/L的HTK液.停搏后取心脏保存于4℃各组相应液体中8 h,然后用37 ℃含氧K-H液再灌注60 min.于平衡灌注10 min(T1)、保存8 h(T2)、复灌60 min(T3)时测定线粒体呼吸功能[3态呼吸(S3)和4态呼吸(S4)的耗氧速率、呼吸控制率(RCR)及磷氧比(P/O)].于T1和T3时收集冠脉流出液测定心肌肌钙蛋白I(cTnI)浓度、肌酸激酶同功酶(CK-MB)及乳酸脱氢酶(LDH)的活性.电镜下观察心肌细胞超微结构.结果 与Ⅰ组比较,Ⅱ组～Ⅳ组RCR、P/O、S3耗氧速率升高,cTnI、CK-MB和LDH的水平降低(P＜0.05).与Ⅱ组比较,Ⅲ组～Ⅴ组RCR、P/O、S3耗氧速率降低,cTnI、CK-MB和LDH的水平升高(P＜0.05).与Ⅲ组比较,Ⅳ组RCR、P/O、S3耗氧速率升高,cTnI、CK-MB和LDH的水平降低,Ⅴ组RCR、P/O、S3耗氧速率降低,cTnI、CK-MB和LDH的水平升高(P＜0.05).与Ⅳ组比较,V组RCR、P/O、S3耗氧速率降低,cTnI、CK-MB和LDH水平升高(P＜0.05).各时点S4耗氧速率组间比较差异无统计学意义(P＞0.05).Ⅱ组心肌细胞损伤较轻,Ⅲ组和Ⅳ组损伤程度相近但重于Ⅱ组,Ⅰ组和Ⅴ组损伤最重.结论 含吡那地尔的HTK液可改善心脏线粒体呼吸功能,减轻心肌损伤,提高心脏保存效果,线粒体ATP敏感性钾通道和细胞膜ATP敏感性钾通道均参与了吡那地尔的心肌保护效应,且线粒体ATP敏感性钾通道发挥主导作用.     

线粒体心磷脂在二氮嗪预处理减轻大鼠离体心脏缺血再灌注损伤中的作用

目的 评价线粒体心磷脂在二氮嗪预处理减轻大鼠离体心脏缺血再灌注损伤中的作用.方法 清洁级SD大鼠72只,体重200～280 g,雌雄各半,随机分为对照组(C组)、缺血再灌注组(I/R组)、二氮嗪预处理组(DZ组)和5-羟葵酸拮抗二氮嗪组(HD组),每组18只.采用Langendorff灌流装置建立大鼠离体心脏缺血再灌注模型,C组平衡灌注20 min,持续灌注100 min;I/R组平衡灌注20 min,持续灌注30 min,缺血40 min,再灌注30 min;DZ组平衡灌注20 min后,依次灌注K-H液15 min、50 μmol/L二氮嗪10 min和K-H液5 min,其余缺血再灌注同I/R组;HD组二氮嗪预处理前给予含5-羟葵酸100 μmol/L K-H液10 min,其余处理同DZ组.各组分别于平衡灌注末(T1)、缺血前即刻(T2)、再灌注末(T3)时随机取6只大鼠,监测心率(HR)、左心室发展压(LVDP)和左心室舒张末压(LVEDP),采用高效液相色谱仪测定心肌线粒体心磷脂含量.结果 与T1,2时比较,各组T3时HR、LVDP降低,LVEDP升高,心肌线粒体心磷脂含量降低(P<0.05);与C组比较,其余3组T3时HR、LVDP降低,LVEDP升高,心肌线粒体心磷脂含量降低(P<0.05);与I/R组比较,DZ组T3时HR、LVDP升高,LVEDP降低,心肌线粒体心磷脂含量升高(P<0.05);与DZ组比较,HD组T3时HR、LVDP降低,LVEDP升高,心肌线粒体心磷脂含量降低(P<0.05).结论 二氮嗪预处理可减轻大鼠离体心脏缺血再灌注损伤,与维持心肌线粒体心磷脂含量有关.     

Effect of Hepatic Preconditioning with the Use of Methylene Blue on the Liver of Wistar Rats Submitted to Ischemia and Reperfusion

Background

The liver may be injured in situations where it is submitted to ischemia, such as partial hepatectomy and liver transplantation. In all cases, ischemia is followed by reperfusion and, although it is essential for the reestablishment of tissue function, reperfusion may cause greater damage than ischemia, an injury characterized as ischemia-reperfusion (I/R) damage. The aim of this work was to analyze the effect of ischemic preconditioning with the use of methylene blue (MB; 15 mg/kg) 5 or 15 minutes before I/R (IRMB5′ and IRMB15′, respectively) on the hepatic injury occurring after I/R.