Molecular aspects of ischaemic postconditioning

[Cardiometabolic efficacy and toxicological evaluation of a pharmacological galanin receptor agonist]

The goal of this study was to examine effects of a novel galanin receptor agonist GalR1-3 [bAla14, His15]-galanine 2-15 (G), obtained by automatic solid-phase synthesis, on the metabolic state of the area at risk and the size of acute myocardial infarction (MI) in rats in vivo and evaluate its toxicity in BALB /c mice. In anesthetized rats, regional ischemia was simulated by coronary artery occlusion and then coronary blood flow was restored. The peptide G was administered intravenously (i.v.) with a bolus after a period of regional ischemia in the dose range of 0.25-3.0 mg/kg. The sizes of MI and the activities of creatine kinase-MB (СK-MB) and lactate dehydrogenase (LDH) in blood plasma were estimated. The effect of administration of the optimal dose of G (1.0 mg/kg) on myocardial content of adenine nucleotides (AN), phosphocreatine (PCr), creatine (Cr) and lactate was studied. I.v. administration of G to rats at a dose of 1.0 mg/kg slightly affected hemodynamic parameters, but reduced MI size by 40% and decreased plasma LDH and CK-MB activity by the end of reperfusion compared to control. These effects were accompanied by a significant improvement in energy state of area at risk (AAR) - an increase in myocardial content of ATP, åAN, PCr and åCr, and combined with a decrease in myocardial lactate level compared with the control. Toxicity of peptide G was studied with a single intraperitoneal injection of 0.5-3.0% solution of the peptide substance to mice. The absence of signs of intoxication and death of animals after G injection in the maximum possible dose did not allow determining the value of the average lethal dose. The results indicate therapeutic potential of the peptide G for preventing myocardial ischemia and reperfusion injury and feasibility for further study of its pharmacological properties and mechanisms of action.

Mechanical post-conditioning in STEMI patients undergoing primary percutaneous coronary intervention

Although early myocardial reperfusion via primary percutaneous coronary intervention (PCI) allows the preservation of left ventricular function and improves outcome, the acute restoration of blood flow may contribute to the pathophysiology of infarction, a complex phenomenon called reperfusion injury. First described in animal models of coronary obstruction, mechanical post-conditioning, a sequence of repetitive interruption of coronary blood flow applied immediately after reopening of the occluded vessel, was able to reduce the infarct size. However, evidence of its real benefit remains controversial. This review describes the mechanisms of post-conditioning action and the different protocols employed focusing on its impact on primary PCI outcome.

Effect of ischemic postconditioning on cerebral edema and the AQP4 expression following hypoxic-eschemic brain damage in neonatal rats

BACKGROUND

A rat model for neonatal hypoxic-ischemic brain damage (HIBD) was established to observe the effect of ischemic postconditioning (IPostC) on cerebral edema and the AQP4 expression following HIBD and to verify the neuroprotection of IPostC and the relationship between changes of AQP4 expression and cerebral edema.

METHODS

Water content was measured with dry-wet method, and AQP4 transcription and the protein expression of the lesions were detected with real-time PCR and immunohistochemistry staining, respectively.

RESULTS

Within 6-48 hours, the degree of ipsilateral cerebral edema was significantly lower in IPostC-15 s/15 s group than in HIBD group. Similar to the HIBD group, the AQP4 transcription and expression in the IPostC group showed a downward and then upward trend. But the expression was still more evident in the HIBD group than in the IPostC-15 s/15 s group. From 24 to 48 hours, IPostC-15 s/15 s decreased the slowing down expression of AQP4.

CONCLUSION

IPostC has neuroprotective effect on neonatal rats with HIBD and it may relieve cerebral edema by regulating the expression of AQP4.

The effect of remote ischemic postconditioning on graft function in patients undergoing living donor kidney transplantation

BACKGROUND

We evaluated whether remote ischemic postconditioning (RiPoC) could improve initial graft function in living donor kidney transplantation (KT).

METHODS

Patients undergoing living donor KT were randomly assigned to either RiPoC (n=30) or control group (n=30). Immediately after reperfusion in the RiPoC group, three cycles of ischemia and reperfusion, lasting 5 min each, were performed on one upper limb. Renal function was assessed before surgery, 2 hr after surgery, and at 12-hr intervals for 96 hr postsurgery by measuring serum creatinine (sCr) and the estimated glomerular filtration rate (eGFR). Urine output and urine creatinine were assessed until postoperative day 7, and hospital stay and complication rates were compared.

RESULTS

The time for sCr to reach 50% of its preoperative level was significantly shorter in the RiPoC group than in the control group [12 (12-24) hr for RiPoC vs. 24 (21-36) hr for the control, P=0.005]. The number of patients whose sCr was reduced by 50% within 24 hr was significantly greater in the RiPoC group than in the control group [n=26 (87%) in RiPoC vs. n=18 (60%) in control, P=0.020]. However, there were no differences in sCr and eGFR thereafter, the incidence of graft dysfunction or complication rates between groups.

CONCLUSION

In this study, RiPoC appeared to hasten the recovery of graft function within 24 hr but did not affect the graft function thereafter. However, considering most recipients had immediate graft function, further studies with deceased donors or studies powered to detect a smaller difference are needed.

Pharmacological evidence for connection of nitric oxide-mediated pathways in neuroprotective mechanism of ischemic postconditioning in mice

INTRODUCTION

Postconditioning (PoCo) is an adaptive phenomenon whereby brief repetitive cycles of ischemia with intermittent reperfusion instituted immediately after prolonged ischemia at the onset of prolonged reperfusion elicit tissue protection. PoCo is noted to exert a protective effect in various organs like heart, liver, kidney and brain. Various triggers, mediators and end effectors are suggested to contribute to the protective effect of PoCo. However, the neuroprotective mechanism of PoCo is poorly understood.

OBJECTIVES

The present study has been designed to investigate the role of nitric oxide pathway in the neuroprotective mechanism of ischemic postconditioning (iPoCo) employing a mouse model of global cerebral ischemia and reperfusion-induced injury.

MATERIALS AND METHODS

Bilateral carotid artery occlusion (BCAO) of 12 min followed by reperfusion for 24 h was employed to produce ischemia and reperfusion (I/R)-induced cerebral injury in mice. Cerebral injury was assessed in the terms of cerebral infarct, memory impairment and motor in-coordination. Brain nitrite/nitrate; acetylcholinesterase activity, thiobarbituric acid reactive species (TBARS) and glutathione level were also estimated.

RESULTS

BCAO followed by reperfusion produced a significant rise in cerebral infarct size, memory impairment and motor incoordination. Further a rise in acetylcholinesterase activity and TBARS level along with fall in brain nitrite/nitrate and glutathione levels was also noted. iPoCo consisting of three episodes of 10 s carotid artery occlusion and reperfusion (instituted immediately after BCAO) significantly attenuated infarct size, memory impairment, motor incoordination as well as altered biochemicals. iPoCo-induced neuroprotective effects were significantly abolished by pretreatment of L-NAME, a nonselective NOS inhibitor.

CONCLUSION

It may be concluded that the nitric oxide pathway probably plays a vital role in the neuroprotective mechanism of iPoCo.

Effect of remote ischemic postconditioning on patients undergoing living donor liver transplantation

The aim of this study was to evaluate the protective effect of remote ischemic postconditioning (RIPostC) on graft function and acute kidney injury (AKI) after living donor liver transplantation (LT). Recipients undergoing elective living donor LT were randomly assigned to either the RIPostC group or the control group. Immediately after reperfusion, 4 cycles of ischemia and reperfusion lasting for 5 minutes each were performed on 1 upper limb in the RIPostC group. Graft function was assessed through evaluations of the serum levels of total bilirubin and liver enzymes and the prothrombin time for 28 days after surgery. The incidence of AKI, as defined by the Risk, Injury, Failure, Loss, and End-Stage Kidney Disease classification, was evaluated within 28 days of the operation. In addition, the incidences of graft dysfunction, acute cellular rejection, and major complications; the 1-, 3-, and 6-month mortality rates; the length of stay in the intensive care unit; and the length of hospital stay were also investigated. In all, 78 patients were enrolled in the analysis (n = 39 in each group). No differences in graft function or clinical outcomes were observed between the groups. The incidences of postoperative AKI were 38% (n = 15) in the RIPostC group and 72% (n = 28) in the control group (P = 0.006). Despite no improvements in postoperative graft function, RIPostC decreased the incidence of postoperative AKI after living donor LT in this study. However, no other clinical benefits with respect to the complication rate, length of hospital stay, or short-term mortality rate were observed. Thus, further studies will be needed to evaluate the clinical efficacy of RIPostC in LT fully.

Upper extremity ischemia is superior to lower extremity ischemia for remote ischemic conditioning of antero-lateral thigh cutaneous blood flow

Remote ischemic conditioning (RIC) is known to improve microcirculation in various settings, but little is known about the impact of the amount of ischemic tissue mass or the limb itself. Since ischemia and subsequent necrosis of flaps is one of the most dreaded complications in reconstructive surgery, adjuvant methods to improve microcirculation are desirable. We therefore performed a randomized trial to compare the effect of arm versus leg ischemia for RIC of the cutaneous microcirculation of the antero-lateral thigh. Forty healthy volunteers were randomized to undergo 5 min of ischemia of either the upper or lower extremity, followed by 10 min of reperfusion.Ischemia was induced by a surgical tourniquet applied to the proximal limb, which was inflated to 250 mmHg for the upper and 300 mgHg for the lower extremity. This cycle was repeated a total of three times. Cutaneous microcirculation was assessed by combined laser doppler spectrophotometry on the antero-lateral aspect of the thigh to measure cutaneous blood flow (BF), relative hemoglobin content (rHb), and oxygen saturation (StO2). Baseline measurements were performed for 10 min, after which the ischemia/reperfusion cycles were begun. Measurements were performed continuously and were afterwards pooled to obtain a mean value per minute. Both groups showed significant increases in all three measured parameters of cutaneous microcirculation after three cycles of ischemia/reperfusion when compared to baseline (BF: 95.1% (P < 0.001) and 27.9% (P = 0.002); rHb: 9.4% (P < 0.001) and 5.9% (P < 0.001), StO2: 8.4% (P = 0.045) and 9.4% (P < 0.001). When comparing both groups, BF was significantly higher in the arm group (P = 0.019 after 11 min., P = 0.009 after 45 min). In conclusions, both ischemic conditioning of the upper and lower extremity is able to improve cutaneous BF on the ALT donor site. However, RIC of the upper extremity seems to be a superior trigger for improvement of cutaneous BF.

Mitochondrial channels: ion fluxes and more

The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.

Tadalafil enhances the neuroprotective effects of ischemic postconditioning in mice, probably in a nitric oxide associated manner

This study investigates the modulatory effect of tadalafil, a selective phosphodiesterase (PDE-5) inhibitor, on the neuroprotective effects of ischemic postconditioning (iPoCo) in mice. Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was employed to produce ischemia and reperfusion induced cerebral injury. Cerebral infarct size was measured using TTC staining. Memory was assessed using the Morris water maze test. Degree of motor incoordination was evaluated using inclined beam-walking, rota-rod, and lateral push tests. Brain nitrite/nitrate, acetylcholinesterase activity, TBARS, and glutathione levels were also estimated. BCAO followed by reperfusion produced a significant increase in cerebral infarct size, brain nitrite/nitrate and TBARS levels, and acetylcholinesterase activity along with a reduction in glutathione. Marked impairment of memory and motor coordination was also noted. iPoCo consisting of 3 episodes of 10 s carotid artery occlusion and reperfusion instituted immediately after BCAO significantly decreased infarct size, memory impairment, motor incoordination, and altered biochemistry. Pretreatment with tadalafil mimicked the neuroprotective effects of iPoCo. The tadalafil-induced neuroprotective effects were significantly attenuated by l-NAME, a nonselective NOS inhibitor. We concluded that tadalafil mimics the neuroprotective effects of iPoCo, probably through a nitric oxide dependent pathway, and PDE-5 could be a target of interest with respect to the neuroprotective mechanism of iPoCo.

Ischaemic conditioning strategies for the nephrologist: a promise lost in translation?

Over the last quarter of a century, a huge effort has been made to develop interventions that can minimise ischaemia reperfusion injury. The most potent of these are the ischaemic conditioning strategies, which comprise ischaemic preconditioning, remote ischaemic preconditioning and ischaemic postconditioning. While much of the focus for these interventions has been on protecting the myocardium, other organs including the kidney can be similarly protected. However, translation of these beneficial effects from animal models into routine clinical practice has been less straightforward than expected. In this review, we examine the role of ischaemic conditioning strategies in reducing tissue injury from the 'bench to the bedside' and discuss the barriers to their greater translation.

The RIPOST-MI study, assessing remote ischemic perconditioning alone or in combination with local ischemic postconditioning in ST-segment elevation myocardial infarction

Local ischemic postconditioning (IPost) and remote ischemic perconditioning (RIPer) are promising cardioprotective therapies in ST-elevation myocardial infarction (STEMI). We aimed: (1) to investigate whether RIPer initiated at the catheterization laboratory would reduce infarct size, as measured using serum creatine kinase-MB isoenzyme (CK-MB) release as a surrogate marker; (2) to assess if the combination of RIPer and IPost would provide an additional reduction. Patients (n = 151) were randomly allocated to one of the following groups: (1) control group, percutaneous transluminal coronary angioplasty (PTCA) alone; (2) RIPer group, PTCA combined with RIPer, consisting of three cycles of 5-min inflation and 5-min deflation of an upper-arm blood-pressure cuff initiated before reperfusion; (3) RIPer+IPost group, PTCA combined with RIPer and IPost, consisting of four cycles of 1-min inflation and 1-min deflation of the angioplasty balloon. The CK-MB area under the curve (AUC) over 72 h was reduced in RIPer, and RIPer+IPost groups, by 31 and 29 %, respectively, compared to the Control group; however, CK-MB AUC differences between the three groups were not statistically significant (p = 0.06). Peak CK-MB, CK-MB AUC to area at risk (AAR) ratio, and peak CK-MB level to AAR ratio were all significantly reduced in the RIPer and RIPer+IPost groups, compared to the Control group. On the contrary, none of these parameters was significantly different between RIPer+IPost and RIPer groups. To conclude, starting RIPer therapy immediately prior to revascularization was shown to reduce infarct size in STEMI patients, yet combining this therapy with an IPost strategy did not lead to further decrease in infarct size.

Emulsified isoflurane protects rat heart in situ after regional ischemia and reperfusion

Volatile anesthetic postconditioning reduces myocardial infarct size against ischemia/reperfusion (I/R) injury. We tested the hypothesis that emulsified isoflurane (EIso) administrated after ischemia exerts cardioprotection in a rat model of myocardial I/R. Male SD rats underwent 30-min coronary occlusion followed by 3-h reperfusion except for sham rats. All vehicles were administrated intravenously at reperfusion onset for 30 min. In the first study, 56 rats were given saline (CON), 30% intralipid (IL) and 1, 2, 4, 8 or 16 mL/kg EIso for infarct size measurement. In a second study, 32 rats were randomized to four groups and administrated saline in sham (sham) and control (CON) groups, 30% intralipid in IL group and 2 mL/kg emulsified isoflurane in EIso group. Cardiomyocytic enzyme activity was determined. Myocardial mitochondria and cytosol were isolated to determine mitochondrial energy metabolism, cytochrome c release, mitochondrial membrane potential (ΔΨm) and opening of the mitochondrial permeability transition pore (mPTP). Morphologic changes in mitochondria were observed by transmission electron microscopy. Compared with CON and IL, 2, 4 and 8 mL/kg EIso limited infarct size (P < 0.01). Serum levels of cardiac enzyme leakage were reduced in EIso-treated hearts compared with CON (P < 0.01 or P < 0.05). EIso preserved the ultrastructure of mitochondria, protected against mPTP opening, decreased cytochrome c release and preserved ATP production and ΔΨm . In conclusion, EIso is effective in reducing infarct size and in preserving mitochondrial function after ischemia and reperfusion injury.

Preconditioning approach in stem cell therapy for the treatment of infarcted heart

Nearly two decades of research in regenerative medicine have been focused on the development of stem cells as a therapeutic option for treatment of the ischemic heart. Given the ability of stem cells to regenerate the damaged tissue, stem-cell-based therapy is an ideal approach for cardiovascular disorders. Preclinical studies in experimental animal models and clinical trials to determine the safety and efficacy of stem cell therapy have produced encouraging results that promise angiomyogenic repair of the ischemically damaged heart. Despite these promising results, stem cell therapy is still confronted with issues ranging from uncertainty about the as-yet-undetermined "ideal" donor cell type to the nonoptimized cell delivery strategies to harness optimal clinical benefits. Moreover, these lacunae have significantly hampered the progress of the heart cell therapy approach from bench to bedside for routine clinical applications. Massive death of donor cells in the infarcted myocardium during acute phase postengraftment is one of the areas of prime concern, which immensely lowers the efficacy of the procedure. An overview of the published data relevant to stem cell therapy is provided here and the various strategies that have been adopted to develop and optimize the protocols to enhance donor stem cell survival posttransplantation are discussed, with special focus on the preconditioning approach.

Myocardial postconditioning: next step to cardioprotection

Myocardial ischemia is a condition in which lack of blood flow to the cardiac muscle occurs resulting in deficient oxygen and nutrient supply to the heart. The restoration of blood flow to an organ or tissue is termed reperfusion. Brief episodes of ischemia and reperfusion given after prolonged ischemia and at the onset of reperfusion denotes postconditioning. Myocardial postconditioning is a phenomenon in which myocardium from lethal ischemia-reperfusion injury is protected. However, numerous experimental studies reveal that the cardioprotective effects of postconditioning are suppressed in various pathological states. This review critically discusses the mechanisms involved in the cardioprotective effects of postconditioning and factors affecting the cardioprotective potential of myocardial postconditioning.

RISK and SAFE signaling pathway interactions in remote limb ischemic perconditioning in combination with local ischemic postconditioning

Local ischemic postconditioning (IPost) and remote ischemic perconditioning (RIPer) are promising methods to decrease ischemia-reperfusion (I/R) injury. We tested whether the use of the two procedures in combination led to an improvement in cardioprotection through a higher activation of survival signaling pathways. Rats exposed to myocardial I/R were allocated to one of the following four groups: Control, no intervention at myocardial reperfusion; IPost, three cycles of 10-s coronary artery occlusion followed by 10-s reperfusion applied at the onset of myocardial reperfusion; RIPer, 10-min limb ischemia followed by 10-min reperfusion initiated 20 min after coronary artery occlusion; IPost+RIPer, IPost and RIPer in combination. Infarct size was significantly reduced in both IPost and RIPer (34.25 ± 3.36 and 24.69 ± 6.02%, respectively) groups compared to Control (54.93 ± 6.46%, both p < 0.05). IPost+RIPer (infarct size = 18.04 ± 4.86%) was significantly more cardioprotective than IPost alone (p < 0.05). RISK pathway (Akt, ERK1/2, and GSK-3β) activation was enhanced in IPost, RIPer, and IPost+RIPer groups compared to Control. IPost+RIPer did not enhance RISK pathway activation as compared to IPost alone, but instead increased phospho-STAT-3 levels, highlighting the crucial role of the SAFE pathway. In IPost+RIPer, a SAFE inhibitor (AG490) abolished cardioprotection and blocked both Akt and GSK-3β phosphorylations, whereas RISK inhibitors (wortmannin or U0126) abolished cardioprotection and blocked STAT-3 phosphorylation. In our experimental model, the combination of IPost and RIPer improved cardioprotection through the recruitment of the SAFE pathway. Our findings also indicate that cross talk exists between the RISK and SAFE pathways.

The additive effects of ischemic postconditioning and cyclosporine-A on nitric oxide activity and functions of diabetic myocardium injured by ischemia/reperfusion

BACKGROUND

The interaction of diabetes with cardioprotection by postconditioning in ischemia/reperfusion injury remains unclear. The aim of this study was to investigate the concomitant effects of ischemic postconditioning (IPostC) and cyclosporine-A (CsA) on nitric oxide (NO) content and parameters of cardiac function of the diabetic myocardium injured by ischemia/reperfusion.

METHODS

Diabetes was induced by single injection of streptozotocin (50 mg/kg; intraperitoneally [ip]) in Wistar rats (250-320 g) and the diabetic period was 8 weeks. The hearts (n = 96) were removed quickly, mounted on Langendorff apparatus, and then subjected to 30-minute regional ischemia followed by 45-minute reperfusion. Ischemic postconditioning was induced by 3 cycles of 30-second reperfusion/ischemia at the onset of reperfusion. Myocardial function was measured throughout the experiment, and infarct size (IS) was identified by triphenyltetrazolium chloride (TTC) staining. Total amounts of NO metabolites were determined using Griess method and enzyme-linked immunosorbent assay (ELISA) reader.

RESULTS

Administration of either IPostC or CsA alone in nondiabetic animals significantly improved myocardial function and reduced the ISs (28% ± 1.9% or 23% ± 2.0% vs 41% ± 2.9% of the risk zone [RZ], respectively; P < .01), but they had no effect on diabetic hearts (35% ± 1.8% or 32% ± 2.1% vs 39% ± 3.1%, respectively). In addition, myocardial NO level was significantly increased by IPostC only in nondiabetic animals (P < .01). However, after administration of CsA (5 minutes before and 10 minutes after the onset of reperfusion) in postconditioned animals, the cardioprotective and NO-enhancing effects of IPostC were restored in diabetic rats (IS: 21% ± 1.1% vs 39% ± 3.1%), similar to those in nondiabetic controls (19% ± 1.3% vs 41% ± 2.9%; P < .01).

CONCLUSION

The present study indicated that IPostC or CsA failed to affect NO levels and failed to protect the diabetic myocardium against ischemia/reperfusion injury. Moreover, concomitant administration of CsA and IPostC at reperfusion can increase NO content and protect the diabetic myocardium.

Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states

Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.

Mitochondria in postconditioning

Several signal transduction pathways are activated by cardioprotective stimuli, including ischemic or pharmacological postconditioning. These pathways converge on a common target, the mitochondria, and cardioprotection by postconditioning is associated with preserved mitochondrial function after ischemia/reperfusion. The present review discusses the role of mitochondria in cardioprotection, especially the involvement of ATP-dependent potassium channels, reactive oxygen species, and the mitochondrial permeability transition pore, and focuses on the effects of postconditioning on mitochondrial function (i.e., their oxygen consumption and calcium retention capacity). The contribution of mitochondria to loss of protection by postconditioning in diseased or aged myocardium is also addressed.

Current protective strategies in liver surgery

During liver resection surgery for cancer or liver transplantation, the liver is subject to ischaemia (reduction in blood flow) followed by reperfusion (restoration of blood flow), which results in liver injury [ischemia-reperfusion (IR) or IR injury]. Modulation of IR injury can be achieved in various ways. These include hypothermia, ischaemic preconditioning (IPC) (brief cycles of ischaemia followed by reperfusion of the organ before the prolonged period of ischaemia i.e. a conditioning response), ischaemic postconditioning (conditioning after the prolonged period of ischaemia but before the reperfusion), pharmacological agents to decrease IR injury, genetic modulation of IR injury, and machine perfusion (pulsatile perfusion). Hypothermia decreases the metabolic functions and the oxygen consumption of organs. Static cold storage in University of Wisconsin solution reduces IR injury and has prolonged organ storage and improved the function of transplanted grafts. There is currently no evidence for any clinical advantage in the use of alternate solutions for static cold storage. Although experimental data from animal models suggest that IPC, ischaemic postconditioning, various pharmacological agents, gene therapy, and machine perfusion decrease IR injury, none of these interventions can be recommended in clinical practice. This is because of the lack of randomized controlled trials assessing the safety and efficacy of ischaemic postconditioning, gene therapy, and machine perfusion. Randomized controlled trials and systematic reviews of randomized controlled trials assessing the safety and efficacy of IPC and various pharmacological agents have demonstrated biochemical or histological improvements but this has not translated to clinical benefit. Further well designed randomized controlled trials are necessary to assess the various new protective strategies in liver resection.

Targeting of adenosine receptors in ischemia-reperfusion injury

IMPORTANCE OF THE FIELD

Ischemia-reperfusion (IR) injury is a common problem after transplantation as well as myocardial infarction and stroke. IR initiates an inflammatory response leading to rapid tissue damage. Adenosine, produced in response to IR, is generally considered a protective signaling molecule and elicits its physiological responses through four distinct adenosine receptors. The short half-life, lack of specificity and rapid metabolism limits the use of adenosine as a therapeutic agent. Thus, intense research efforts have focused on the synthesis and implementation of specific adenosine receptor agonists and antagonists as potential therapeutic agents for a variety of inflammatory conditions including IR injury.

AREAS COVERED IN THIS REVIEW

Current knowledge on IR injury with a focus on lung, heart and kidney and studies that have advanced our understanding of the role of adenosine receptors and the therapeutic potential of adenosine receptor agonists and antagonists for the prevention of IR injury.

WHAT THE READER WILL GAIN

Insight into the role of adenosine receptor signaling in IR injury.

TAKE HOME MESSAGE

No therapies are currently available that specifically target IR injury; however, targeting of specific adenosine receptors may offer therapeutic strategies in this regard.

Modulation of neuroprotective effect of ischemic post-conditioning by dichlorobenzamil a Na(+)/Ca(2+) exchanger inhibitor in mice

The present study has been designed to investigate the modulatory role of dichlorobenzamil a Na(+)/Ca(2+) exchanger inhibitor in ischemic post-conditioning-induced neuroprotection in mice. Bilateral carotid artery occlusion followed by reperfusion, produced a significant rise in cerebral infarct size along with impairment of memory and motor coordination. Ischemic post-conditioning involving three episodes of 10 s carotid artery occlusion with intermittent reperfusion of 10 s proceeding prolonged ischemic insult of 12 min, produced a significant decrease in cerebral infarct size along with reversal of ischemia-reperfusion-induced impairment of memory and motor coordination. Ischemic post-conditioning-induced neuroprotective effects were significantly abolished by pretreatment with dichlorobenzamil (DBZ 0.5, 1 mg/kg, intraperitoneal) a Na(+)/Ca(2+) exchange inhibitor. It may be concluded that Na(+)/Ca(2+) exchanger possibly plays an important role in ischemic post-conditioning-induced neuroprotection.