Skeletal Muscle Reperfusion Injury Research Articles

Beneficial Effects of Insulin on Ischemia Reperfusion Injury in Human Skeletal Muscle.

PurposeExaggerated leucocyte activity is a crucial step in the pathophysiology of skeletal muscle ischemia-reperfusion injury (IRI). We tested the hypothesis that insulin, via its’ anti-leukocyte activity, attenuates skeletal muscle IRI in humans.MethodsMaterials and This randomized, blinded, placebo-controlled trial was conducted in patients with skeletal muscle ischemia who required revascularization. Treatment protocols were similar among them except for the insulin group, which received an infusion of insulin at 2.5 U/h. The degree of endothelial adhesiveness; leukocyte activity and pro-inflammatory status via P-selectin, tumor necrosis factor (TNF)-alpha, and myeloperoxidase (MPO) levels in the venous effluent; and clinical outcomes were measured.ResultsTwenty-four consenting patients were randomized to the insulin or control group. There were no significant differences between the two groups except for the median serum insulin level, which was higher in the insulin group (P<0.01). No serious intervention-related adverse events were observed. P-selectin (55.04-99.86 pg/mL; P<0.001), MPO (110.8-160.6 pg/mL; P<0.001), and TNF-alpha (12.16-36.01 pg/mL; P<0.001) levels demonstrated a significant increase post-reperfusion in the ‘control’ group, reaching a peak value at 2 hours post-reperfusion. The increase in all three markers from baseline was significantly diminished in the insulin group at the two-hour (P-selectin, P=0.001; MPO, P=0.001; TNF-alpha, P=0.005) and four-hour (P-selectin, P=0.003; MPO, P=0.002; TNF-alpha, P=0.01) intervals. The differences in clinical outcomes between the insulin and control groups were not statistically significant.ConclusionIn clinical practice, insulin has the potential to attenuate the severity of skeletal muscle IRI inhibiting P-selectin, MPO, and TNF-alpha levels.

Protective effects of epigallocatechin gallate against ischemia reperfusion injury in rat skeletal muscle via activating Nrf2/HO-1 signaling pathway

AimsPrevious studies have demonstrated that epigallocatechin gallate (EGCG) had certain protective effects on myocardial and renal ischemia reperfusion (I/R) injury. We aimed to research the special effects and underling mechanisms of EGCG on skeletal muscle I/R injury. Main methodWe established an experimental rat model of I/R skeletal muscle injury and treated with different doses of EGCG. Hematoxylin eosin staining, TUNEL assay, ELISA, qRT-PCR and Western blotting were used to evaluate the effects of EGCG. Key findindsEGCG significantly improved skeletal muscle function of I/R injury rats. Moreover, EGCG had positive effects on decreasing apoptosis of skeletal muscle tissues, alleviating oxidative stress damage and suppressing the production of inflammatory cytokines. Further, EGCG had positive effects on activating Nrf2/HO-1 signaling pathway. SignificanceEGCG might be a powerful candidate compound for alleviating I/R injury in rat skeletal muscle.

Applying C60 Fullerenes Improve the Physiological State of Rats with Ischemia–Reperfusion Injury of Skeletal Muscle

Applying C60 Fullerenes Improve the Physiological State of Rats with Ischemia–Reperfusion Injury of Skeletal Muscle

An optimized low-pressure tourniquet murine hind limb ischemia reperfusion model: Inducing acute ischemia reperfusion injury in C57BL/6 wild type mice.

Acute ischemia reperfusion injury in skeletal muscle remains an important issue in several fields of regenerative medicine. Thus, a valid model is essential to gain deeper insights into pathophysiological relations and evaluate possible treatment options. While the vascular anatomy of mice regularly prevents sufficient vessel occlusion by invasive methods, there is a multitude of existing models to induce ischemia reperfusion injury without surgical procedures. Since there is no consensus on which model to prefer, this study aims to develop and evaluate a novel, optimized low-pressure tourniquet model. C57BL/6 mice underwent an ischemic procedure by either tourniquet or invasive artery clamping. A sham group served as control. With exception of the sham group, mice underwent 2 hours of ischemia followed by 4 hours of reperfusion. Groups were compared using microcirculatory and spectroscopic measurements, distinctions in tissue edema, histological and immunohistochemical analyses. Both procedures led to a significant decrease in tissue blood flow (- 97% vs. - 86%) and oxygenation (- 87% vs. - 75%) with a superiority of the low-pressure tourniquet. Tissue edema in the tourniquet cohort was significantly increased (+ 59%), while the increase in the clamping cohort was non-significant (+ 7%). Haematoxylin Eosin staining showed significantly more impaired muscle fibers in the tourniquet group (+ 77 p.p. vs. + 11 p.p.) and increased neutrophil infiltration/ROI (+ 51 vs. + 8). Immunofluorescence demonstrated an equal increase of p38 in both groups (7-fold vs. 8-fold), while the increase in apoptotic markers (Caspase-3, 3-Nitrotyrosine, 4-Hydroxynonenal) was significantly higher in the tourniquet group. The low-pressure tourniquet has been proven to produce reproducible and thus reliable ischemia reperfusion injury. In addition, significantly less force was needed than previously stated. It is therefore an important instrument for studying the pathophysiology of ischemia reperfusion injury and for the development of prophylactic as well as therapeutic interventions.

The protective effect of Montelukast against skeletal muscle ischemia reperfusion injury: An experimental rat model.

Montelukast is a selective leukotriene D-4 receptor antagonist, which specifically and reversibly inhibits cysteinyl leukotriene-1 receptor. The aim of this study was to investigate the protective effect of Montelukast on skeletal muscle reperfusion injury created as acute ischemia-reperfusion (IR) injury in Wistar-albino rats. The study comprised 16 male Wistar-albino rats. The rats were randomly separated into two groups as control (IR) and treatment (IR+Montelukast). Ischemia was obtained using a femoral artery clamp. After reperfusion following a 2-hour ischemia, muscle samples were taken for biochemical and histopathological analyses. Malondialdehyde levels were determined to be at statistically higher levels in the control compared with that in the Montelukast group (p=0.002, p<0.01). The superoxide dismutase levels were determined to be at statistically higher level in the Montelukast group compared with that in the control group (p=0.001, p<0.01). In the histopathological examination of the ischemic muscles, edema, polymorinfiltration and erythrocyte extravasation levels were found to be statistically significant higher in the control group than in the Montelukast group. Edema, polymorphonuclear infiltration, and erythrocyte extravasation levels were observed to be significantly reduced in the treatment group compared with that in the control. In this model of skeletal muscle acute IR injury, the protective effect of Montelukast against skeletal muscle reperfusion injury was emphasized. We concluded that Montelukast could accelerate functional recovery in the extremity by limiting the local and systemic complications caused by reperfusion in cases such as extremity trauma with vascular injuries and extremity surgery with prolonged tourniquet application. However, further experimental and clinical studies are required to confirm this effect.

The Protective Effects of Fasciotomy on Reperfusion Injury of Skeletal Muscle of Rabbits.

The authors aim to investigate protective effects of fasciotomy against ischemia reperfusion injury of skeletal muscle in rabbit and to compare the treatment effects of prereperfusion + fasciotomy and fasciotomy + postreperfusion against ischemia reperfusion injury of skeletal muscle. 24 healthy male Japanese white rabbits were randomly divided into 3 groups, and 4 hours' ischemia was established in these rabbits through surgery. Six hours' reperfusion was performed in group A; reperfusion + postfasciotomy was performed in group B; and prefasciotomy + reperfusion was performed in group C. Result showed that prefasciotomy and postfasciotomy could protect skeletal muscle against ischemia reperfusion injury, reduced MDA (malondialdehyde) expression, MPO (myeloperoxidase) expression, and apoptosis of muscle in the reperfused areas, increased Bcl-2 expression, and decreased Bax expression. The MDA and MPO levels in group B and group C were significantly lower than those in group A, and MDA and MPO levels in group C were significantly lower than those in group B. Prefasciotomy and postfasciotomy could protect against ischemia reperfusion injury in skeletal muscle. The protective effects of prefasciotomy against ischemia reperfusion injury are better than postfasciotomy.

Mechanism of vacuum sealing drainage therapy attenuating ischemia-reperfusion injury of skeletal muscle in rabbit

To investigate the mechanism of how vacuum sealing drainage (VSD) ameliorating ischemia reperfusion (I/R) injury in skeletal muscle I/R model. Thirty New Zealand white rabbits were divided into three groups: control (sham operation) group, I/R group, VSD+ I/R group.The ischemia of the left hind limb of the animal was induced by clamping the common femoral artery and vein. After 4 hours of ischemia, the clamp was removed and the hind limp underwent 6 hours reperfusion. VSD treated animals received the treatment at the beginning of reperfusion. The concentrations of myeloperoxidase (MPO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) in muscular tissues were assayed. HE stained pathological section was used to evaluate the degree of edema of muscular tissues, and the immunohistochemistry was used to detect the percentage of positive cells expressing high mobility group protein B1 (HMGB1). Q-RT-PCR and Western Blot were used to detect the mRNA levels and protein expression of HMGB1 in myocyte respectively. The experimental data was tested using variance analysis. The levels of inflammatory factors and antioxidant factors in muscular tissues were significantly different in the I/R group compared to the VSD group and control group (the levels of MPO in I/R group, I/R+ VSD group and control group were 0.91±0.22, 0.53±0.08, 0.31±0.10, respectively, F=26.48, P=0.000; MDA were 2.04±0.92, 1.65±1.02, 1.01±0.12, F=4.250, P=0.040; SOD were 35.97±9.23, 55.99±18.97, 61.83±14.91, F=5.240, P=0.020; CAT were 31.42±16.27, 48.50±17.86, 75.95±13.09, F=9.720, P=0.002; GSH were 1.48±0.90, 3.54±1.88, 3.84±2.08, F=5.240, P=0.020). HE staining showed an increased intercellular space ratio in the I/R group (F=16.47, P<0.05). Immunohistochemistry staining showed that percentage of HMGB1 positive myocytes in control, I/R and I/R+ VSD group are 1.94%, 18.63% and 61.36%, respectively. There was significant difference among groups (F=853.886, P<0.01). A significantly inhibited HMGB1 expression by VSD therapy was also validated by the results of Q-RT-PCR (F=50.653, P<0.01) and Western blot (F=963.489, P<0.01). The results from the present research suggest that VSD may attenuate skeletal muscles I/R injury by increasing the cellular antioxidative stress reaction and inhibiting the reactive oxygen species as well as the inflammatory mediators.

Evaluation and comparison of the effect of hypothermia and ozone on ischemia–reperfusion injury of skeletal muscle in rats

BackgroundTourniquet-induced ischemia–reperfusion, which affects local and distant organs, is very common in orthopedic surgery. Hypothermia is used in traumatic tissue during ischemic period commonly. Ozone (O3) has been recommended as a novel therapeutic agent in various medical conditions. The objective of the study was to evaluate and compare the effect of hypothermia (H) and O3 on ischemia–reperfusion injury of skeletal muscle in rats by measuring oxidative parameters and inducible nitric oxide synthase (iNOS) levels. Materials and methodsEighteen rats (Wistar albino) were separated into five groups randomly (sham, IR, IR + H, IR + O3, IR + H + O3; n = 6). The lower right extremity of all rats was subjected to 2 h of ischemia and 22 h of reperfusion clamping the common iliac artery and using the rubber-band technique at the level of the lesser trochanter under general anesthesia. Two hours of hypothermia were applied during the first 2 h of reperfusion in two groups. O3 was applied in two groups. All rats were sacrificed after the IR period with high dose of anesthesia. The tibialis anterior muscle and blood were saved. Levels of superoxide dismutase, glutathione peroxidase, MDA, NOx, and interleukin-1β were measured in the muscle. Creatinine kinase, lactate dehydrogenase, aspartate aminotransferase, urea, creatinine, and electrolytes were measured in serum. Immunohistochemical iNOS staining was performed on muscle samples. ResultsThe levels of MDA, NOx, and interleukin-1β in muscle were raised in the IR group compared with those in the sham group. The same parameters were lower in the groups of IR + H, IR + O3, and IR + H + O3 compared with those in the IR group. Superoxide dismutase and glutathione peroxidase activities in muscle were lower in the IR group compared with those in the sham group; however, same parameters were higher in the groups of IR + H, IR + O3, and IR + H + O3 compared with those in the IR group. Score and intensity of iNOS staining in skeletal muscle in the IR group was increased compared with that in the sham group and decreased in the groups of IR + H, IR + O3, and IR + H + O3 compared with that in the IR group. Levels of creatinine kinase, aspartate aminotransferase, and K in the three treatment groups decreased compared with those in the IR group. ConclusionsThese findings showed that hypothermia, which has more affect, and O3 decreased the tourniquet-induced IR injury in the rat's muscle-skeletal system by reducing the levels of oxidative and nitrosative stress parameters and enhancing antioxidant enzymes. Hypothermia and O3 had no synergistic effect. Hypothermic reperfusion and O3 preconditioning might be beneficial in skeletal muscle IR injury-associated tourniquet.

Protective Effect of Focal Adhesion Kinase against Skeletal Muscle Reperfusion Injury after Acute Limb Ischemia

In cardiac muscle, ischemia reperfusion (IR) injury is attenuated by mitochondrial function, which may be upregulated by focal adhesion kinase (FAK). The aim of this study was to determine whether increased FAK levels reduced rhabdomyolysis in skeletal muscle too. In a translational in vivo experiment, rat lower limbs were subjected to 4 hours of ischemia followed by 24 or 72 hours of reperfusion. FAK expression was stimulated 7 days before (via somatic transfection with pCMV-driven FAK expression plasmid) and outcomes were measured against non-transfected and empty transfected controls. Slow oxidative (i.e., mitochondria-rich) and fast glycolytic (i.e., mitochondria-poor) type muscles were analyzed separately regarding rhabdomyolysis, apoptosis, and inflammation. Severity of IR injury was assessed using paired non-ischemic controls. After 24 hours of reperfusion, marked rhabdomyolysis was found in non-transfected and empty plasmid-transfected fast-type glycolytic muscle, tibialis anterior. Prior transfection enhanced FAK concentration significantly (p = 0.01). Concomitantly, levels of BAX, promoting mitochondrial transition pores, were reduced sixfold (p = 0.02) together with a blunted inflammation (p = 0.01) and reduced rhabdomyolysis (p = 0.003). Slow oxidative muscle, m. soleus, reacted differently: although apoptosis was detectable after IR, rhabdomyolysis did not appear before 72 hours of reperfusion; and FAK levels were not enhanced in ischemic muscle despite transfection (p = 0.66). IR-induced skeletal muscle rhabdomyolysis is a fiber type-specific phenomenon that appears to be modulated by mitochondria reserves. Stimulation of FAK may exploit these reserves constituting a potential therapeutic approach to reduce tissue loss following acute limb IR in fast-type muscle.

Commentary on ‘Protective Effect of Focal Adhesion Kinase Against Skeletal Muscle Reperfusion Injury After Acute Limb Ischemia’

Commentary on ‘Protective Effect of Focal Adhesion Kinase Against Skeletal Muscle Reperfusion Injury After Acute Limb Ischemia’

Effect of Exercise Training on Endogenous Stem Cells Activation in Ischemia Reperfusion Induced Skeletal Muscle Injury: A Physio- Histological Study

Background: This study aimed at investigating the possible role of exercise training in activating the migration of CD34 positive progenitor cells in a rat model of induced ischemia reperfusion injury (IRI) of limb skeletal muscle and related regeneration potential. Material and methods: 28 adult male albino rats were divided into three groups: group I: control group; group II: IRI with 2 hours ischemia and 2 hours reperfusion, followed by immediate sacrifice (subgroup IIa) or delayed sacrifice after two weeks (subgroup IIb); group III: exercise in the form of group and gradual swimming for 4 weeks, followed by IRI and immediate sacrifice (subgroup IIIa), or delayed sacrifice (subgroup IIIb). Muscle performance was evaluated by physiological tests. Histological study was done using H&E staining, and immunohistochemical staining using anti αSMA and anti CD34. Areas of regenerating fibers, area of αSMA and area percentage of CD34 were measured. Statistical analysis was performed. Results: IRI group showed severe muscle damage in IIa in the form of wavy, disrupted darkly acidophilic fibers, many dark nuclei, and extravasated blood. There was some improvement in IIb in the form of regenerating fibres with central nuclei and increased αSMA and CD34 immunostaining. Group III showed better preservation of muscle fibers in IIIa. It also showed significant increase in area of regenerating fibers and statistically significant increase in area of αSMA and CD34 and in physiological parameters in IIIb as compared to group II. Conclusion: Exercise training prior to skeletal muscle IRI markedly improved muscle outcome through preservation and regeneration. Two populations of skeletal muscle stem cells, namely progenitor cells and satellite cells were involved in the process.

Protective Effect of Focal Adhesion Kinase against Skeletal Muscle Reperfusion Injury after Acute Limb Ischemia

In cardiac muscle, ischemia reperfusion (IR) injury is attenuated by mitochondrial function, which may be upregulated by focal adhesion kinase (FAK). The aim of this study was to determine whether increased FAK levels reduced rhabdomyolysis in skeletal muscle too. In a translational invivo experiment, rat lower limbs were subjected to 4 hours of ischemia followed by 24 or 72 hours of reperfusion. FAK expression was stimulated 7 days before (via somatic transfection with pCMV-driven FAK expression plasmid) and outcomes were measured against non-transfected and empty transfected controls. Slow oxidative (i.e., mitochondria-rich) and fast glycolytic (i.e., mitochondria-poor) type muscles were analyzed separately regarding rhabdomyolysis, apoptosis, and inflammation. Severity of IR injury was assessed using paired non-ischemic controls. After 24 hours of reperfusion, marked rhabdomyolysis was found in non-transfected and empty plasmid-transfected fast-type glycolytic muscle, tibialis anterior. Prior transfection enhanced FAK concentration significantly (p= 0.01). Concomitantly, levels of BAX, promoting mitochondrial transition pores, were reduced sixfold (p= 0.02) together with a blunted inflammation (p= 0.01) and reduced rhabdomyolysis (p= 0.003). Slow oxidative muscle, m. soleus, reacted differently: although apoptosis was detectable after IR, rhabdomyolysis did not appear before 72 hours of reperfusion; and FAK levels were not enhanced in ischemic muscle despite transfection (p= 0.66). IR-induced skeletal muscle rhabdomyolysis is a fiber type-specific phenomenon that appears to be modulated by mitochondria reserves. Stimulation of FAK may exploit these reserves constituting a potential therapeutic approach to reduce tissue loss following acute limb IR in fast-type muscle.

Hydrogen-rich saline attenuates ischemia–reperfusion injury in skeletal muscle

BackgroundTo investigate the potential beneficial effect of hydrogen-rich saline (HRS) in ischemia–reperfusion (IR) injury of skeletal muscle. MethodsThree experimental groups were established in male Sprague–Dawley rats: (1) sham group, (2) IR with normal saline group, (3) and IR with HRS group. A rat model of skeletal muscle IR injury was induced by 3-h tourniquet occlusion on its left hind limb and 4-h reperfusion. Normal saline and HRS (1.0 mL/100 g) were administered intraperitoneally at 10 min before reperfusion, respectively. Muscle and serum samples were analyzed for detecting the levels of myeloperoxidase (MPO), superoxide dismutase (SOD), malondialdehyde (MDA), and hydroxyl radical (•OH). Muscle samples were assessed by wet/dry rate, hematoxylin and eosin histologic assessment, Bcl2, Bax, cytochrome C, LC3B, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, and electron microscopy. ResultsThe wet/dry ratio increased significantly in the IR group (P < 0.01 compared with that in the sham group) and decreased significantly in IR with HRS groups (4.12 ± 0.14 versus 4.12 ± 0.14, P < 0.01 compared with that in the IR group). Muscle tissues and serum of the IR group had significantly increased levels of MPO, MDA, •OH content, and decreased SOD activities compared with the sham group (P < 0.01). The activity of SOD in the IR with HRS group was greatly elevated compared with that in the IR group (295.028 ± 9.288 versus 249.190 ± 5.450 in muscle tissues; 91.627 ± 2.604 versus 73.4045 ± 6.487 in serum; P < 0.01), whereas the levels of MPO, MDA, and •OH content were clearly reduced (MPO: 0.5649 ± 0.0724 versus 1.0984 ± 0.0824 in muscle tissues; 0.7257 ± 0.1232 versus 1.3147 ± 0.0531 in serum. MDA: 4.457 ± 0.650 versus 7.107 ± 0.597 in muscle tissues; 2.531 ± 0.434 versus 4.626 ± 0.237 in serum. •OH: 16.451 ± 0.806 versus 19.871 ± 0.594 in muscle tissues; 500.212 ± 7.387 versus 621.352 ± 7.591 in serum, P < 0.01). The integrated optical density of positive amethyst staining increased significantly in the IR group (P < 0.01 compared with that in the sham group) and decreased significantly in IR with HRS group (928.79 ± 234.537 versus 3005.972 ± 83.567, P < 0.01 compared with that in the IR group). Muscle tissues of the IR group had significantly increased levels of Bax, cytochrome C, LC3B content, and decreased Bcl2 activities compared with those in the sham group (P < 0.01). The activity of Bcl2 in the IR with HRS group was greatly elevated compared with that in the IR group (0.2635 ± 0.0704 versus 0.1242 ± 0.0662; P < 0.01), whereas the levels of Bax, cytochrome C, and LC3B content were clearly reduced (Bax: 0.3103 ± 0.0506 versus 0.5122 ± 0.0148; cytochrome C: 0.4194 ± 0.1116 versus 0.8127 ± 0.0166; LC3B: 0.5884 ± 0.0604 versus 1.3758 ± 0.0319; respectively, P < 0.01). ConclusionsHRS seems to be effective in attenuating IR injury in skeletal muscle via its antioxidant, anti-apoptosis, and anti-autophagy effect.

Influence of tramadol on ischemia–reperfusion injury of rats' skeletal muscle

Introduction: Tramadol has been shown to decrease ischemia–reperfusion injuries in myocardial or brain tissues. The aim of this study was to assess the effects of tramadol on ischemia–reperfusion injury in a rat hind limb ischemia–reperfusion model.Methods: Forty-five healthy adult male Wistar rats were randomized into three experimental groups as follows: Sham, Ischemia–reperfusion and Ischemia–reperfusion + tramadol groups. Ischemia was induced in anesthetized rats by left femoral artery clipping for 2 h followed by 24 h of reperfusion. Tramadol (20 mg/kg) was administered intravenously immediately prior to reperfusion. Blood pH, pO2, pCO2, HCO3, creatine phosphokinase (CPK), lactate dehydrogenase (LDH) as well as plasma malondialdehyde (MDA) were measured at the end of the reperfusion. Left gastrocnemius muscle samples were taken for histological and biochemical examination.Results: The pH and pCO2 were similar in all study groups, with no statistical significance. pO2 and HCO3 levels presented the highest elevation in sham and Ischemia–reperfusion + tramadol groups, as compared to Ischemia–reperfusion group (P < 0.05). The extent of muscle changes in the ischemia–reperfusion + tramadol group was significantly lower than ischemia–reperfusion group (P < 0.05). In comparison with other groups, serum and tissue MDA levels in ischemia–reperfusion group were significantly increased (P < 0.05). The muscle tissue glutathione (GSH), superoxide dismutases (SOD) and catalase (CAT) levels in the Ischemia–reperfusion group were significantly lower than the other groups (P < 0.05). Wet/dried weight ratio in ischemia–reperfusion group was significantly higher (P < 0.05) than subjects in other groups.Conclusions: From the histological, histochemical and serum biochemical perspective, the treatment with tramadol has alleviated the metabolic injuries in the skeletal muscle ischemia and reperfusion in this experimental model.

Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris)

Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH) based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb) concentrations in the longissimus dorsi (LD) muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults) may provide a protection against ischemia reperfusion (IR) injury in vasoconstricted peripheral skeletal muscle.

Use of dextran sulfate in tourniquet-induced skeletal muscle reperfusion injury

BackgroundLower extremity ischemia–reperfusion injury (IRI)—prolonged ischemia and the subsequent restoration of circulation—may result from thrombotic occlusion, embolism, trauma, or tourniquet application in surgery. The aim of this study was to assess the effect of low-molecular-weight dextran sulfate (DXS) on skeletal muscle IRI. MethodsRats were subjected to 3 h of ischemia and 2 or 24 h of reperfusion. To induce ischemia the femoral artery was clamped and a tourniquet placed under the maintenance of the venous return. DXS was injected systemically 10 min before reperfusion. Muscle and lung tissue samples were analyzed for deposition of immunoglobulin M (IgM), IgG, C1q, C3b/c, fibrin, and expression of vascular endothelial-cadherin and bradykinin receptors b1 and b2. ResultsAntibody deposition in reperfused legs was reduced by DXS after 2 h (P < 0.001, IgM and IgG) and 24 h (P < 0.001, IgM), C3b/c deposition was reduced in muscle and lung tissue (P < 0.001), whereas C1q deposition was reduced only in muscle (P < 0.05). DXS reduced fibrin deposits in contralateral legs after 24 h of reperfusion but did not reduce edema in muscle and lung tissue or improve muscle viability. Bradykinin receptor b1 and vascular endothelial-cadherin expression were increased in lung tissue after 24 h of reperfusion in DXS-treated and non-treated rats but bradykinin receptor b2 was not affected by IRI. ConclusionsIn contrast to studies in myocardial infarction, DXS did not reduce IRI in this model. Neither edema formation nor viability was improved, whereas deposition of complement and coagulation components was significantly reduced. Our data suggest that skeletal muscle IRI may not be caused by the complement or coagulation alone, but the kinin system may play an important role.

Dexmedetomidine protects against ischemia–reperfusion injury in rat skeletal muscle

BackgroundDexmedetomidine (DEX) has been shown to decrease ischemia–reperfusion (I/R) injury in kidney and brain tissues. In this study, the effects of DEX were evaluated in skeletal muscle during I/R injury. Materials and methodsAnimals were divided into four groups: sham-operated (sham group), saline + I/R, DEX + I/R, and α-tocopherol + I/R groups. Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4 h of ischemia, the clamp was removed and the animals underwent 2 h of reperfusion. Animals in the drug treatment group received DEX or α-tocopherol by intraperitoneal injection 1 h before reperfusion. We measured plasma concentrations of interleukin 1β and tumor necrosis factor α levels using an enzyme-linked immunosorbent assay. The right gastrocnemius muscle was harvested and immediately stored at −80°C for the assessment of superoxide dismutase (SOD) and catalase (CAT) activities as well as glutathione (GSH), malondialdehyde (MDA), and protein oxidation (PO) levels. DEX (25 μg/kg) and normal saline (10 mL/kg) were administered by intraperitoneal injection 1 h before reperfusion. ResultsPlasma tumor necrosis factor α or interleukin 1β levels increased significantly in the I/R group (P < 0.01 compared with sham group) and decreased significantly in the DEX group (P < 0.01 compared with I/R group). Muscle tissues of the I/R group had significantly decreased SOD, GSH, and CAT activities and increased levels of MDA and PO content compared with the sham group. The activity of antioxidant enzymes in the DEX + I/R group was greatly elevated compared with that in the I/R group (SOD, 1.068 ± 0.120 versus 0.576 ± 0.072 U/mg protein; GSH, 2.436 ± 0.144 versus 1.128 ± 0.132 μmol/g; and CAT, 69.240 ± 6.456 versus 31.884 ± 6.312 U/mg protein; P < 0.01), whereas the levels of MDA and PO content were clearly reduced (23.268 ± 3.708 versus 53.604 ± 5.972 nmol/g protein and 1.908 ± 0.192 versus 5.208 ± 0.612 nmol/mg protein, respectively; P < 0.01). Moreover, DEX exhibited more potent antioxidant activity than vitamin E in the skeletal muscle I/R. ConclusionsWe found that DEX exhibits protective effects against skeletal muscle I/R injury. These results underscore the necessity of human studies with DEX to determine if it is beneficial for preventing skeletal muscle I/R injury.

Effects of ischemic postconditioning and preconditioning against ischemic reperfusion injury of skeletal muscle

Objective To study the protective effects of ischemic postconditioning and preconditioning against ischemic reperfusion injury of skeletal muscle.Methods According to different treatment methods on ischemia-reperfusion injury,forty Wistar rats were divided into I/R group,IPost group,IPC group,IPC + IPost group,control group.Using a rat amputation-like model,Wistar rats underwent temporary amputation at the level of the femur,excluding the femoral vessels.By measuring MDA,MPO,the extent of skeletal muscle infarction,protective effects of postconditioning and preconditioning,postconditioning combined with preconditioning were observed.Results In the Ipost group,IPC group,IPC + Ipost group,MDA and MPO at one hour of reperfusion and extent of muscle infarction at 6 hour of reperfusion was lower than group IR (P ＜ 0.05).In the Ipost group,MDA,MPO and extent of muscle infarction was similar to group IPC + Ipost; In the Ipost group,MDA and MPO was lower than group IPC,extent of muscle infarction was similar to group IPC.Conclusion Ischemic postconditioning at the beginning of reperfusion can protect skeletal muscle against ischemic reperfusion injury.Preconditioning also protect skeletal muscle against ischemic reperfusion injury,but preconditioning combined with postconditioning don't offer additional benefit over preconditioning or postconditioning alone. Key words: Ischemic reperfusion; Skeletal muscle; Ischemic postconditioning; Ischemic preconditioning

The comparison of the effects of anesthetic doses of ketamine, propofol, and etomidate on ischemia–reperfusion injury in skeletal muscle

The fact that a considerable amount of clinical conditions suffering from ischemia-reperfusion injury (IRI) occur under general anesthesia has triggered researchers to focus on the effects of anesthetic drugs on IRI. Hence, the aim of this study was to compare the use of different anesthetic drugs in a skeletal IRI model. Tourniquet IRI method was performed and two experimental groups were established as sham-control and IRI group. Rats in each group were anesthetized either with thiopental, ketamine, propofol or etomidate. Malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase were measured in skeletal muscle via a spectrophotometer. Zinc, iron, copper, and selenium were evaluated by atomic absorption spectrophotometer. In rats anesthetized with thiopental (40 mg/kg, i.p.), malondialdehyde values in IRI group were higher and glutathion peroxidase levels were lower compared to sham-control group. However, superoxide dismutase and catalase activities were identical. On the other hand, while the level of zinc in IRI group attenuated, no differences in iron and copper values were determined. Rats anesthetized with ketamine (60 mg/kg), propofol (100 mg/kg), or etomidate (20 mg/kg) did not show increased malondialdehyde levels in comparison with control levels. While the drugs did not cause a distinction in the levels of superoxide dismutase, catalase, glutathion peroxidase, iron, and copper, zinc was in a lower level in IRI group compared to sham-control. In conclusion, ketamine, propofol, and etomidate, with anesthetic doses, denoted efficacious effects on IRI; hence the drugs might be preferred in certain operations with the risk of IRI.

Extracellular BCL2 Proteins Are Danger-Associated Molecular Patterns That Reduce Tissue Damage in Murine Models of Ischemia-Reperfusion Injury

BackgroundIschemia-reperfusion (I/R) injury contributes to organ dysfunction in a variety of clinical disorders, including myocardial infarction, stroke, organ transplantation, and hemorrhagic shock. Recent investigations have demonstrated that apoptosis as an important mechanism of cell death leading to organ dysfunction following I/R. Intracellular danger-associated molecular patterns (DAMPs) released during cell death can activate cytoprotective responses by engaging receptors of the innate immune system.Methodology/Principal FindingsIschemia was induced in the mouse hind limb by tourniquet or in the heart by coronary artery ligation. Reperfusion injury of skeletal or cardiac muscle was markedly reduced by intraperitoneal or subcutaneous injection of recombinant human (rh)BCL2 protein or rhBCL2-related protein A1 (BCL2A1) (50 ng/g) given prior to ischemia or at the time of reperfusion. The cytoprotective activity of extracellular rhBCL2 or rhBCL2A1 protein was mapped to the BH4 domain, as treatment with a mutant BCL2 protein lacking the BH4 domain was not protective, whereas peptides derived from the BH4 domain of BCL2 or the BH4-like domain of BCL2A1 were. Protection by extracellular rhBCL2 or rhBCL2A1 was associated with a reduction in apoptosis in skeletal and cardiac muscle following I/R, concomitant with increased expression of endogenous mouse BCL2 (mBCL2) protein. Notably, treatment with rhBCL2A1 protein did not protect mice deficient in toll-like receptor-2 (TLR2) or the adaptor protein, myeloid differentiation factor-88 (MyD88).Conclusions/SignificanceTreatment with cytokine-like doses of rhBCL2 or rhBCL2A1 protein or BH4-domain peptides reduces apoptosis and tissue injury following I/R by a TLR2-MyD88-dependent mechanism. These findings establish a novel extracellular cytoprotective activity of BCL2 BH4-domain proteins as potent cytoprotective DAMPs.