Possible involvement of erythropoietin in remote renal preconditioning-induced cardioprotection in rats.
ABSTRACT Remote preconditioning is a unique phenomenon in which brief episodes of ischemia and reperfusion to remote organs protect the target organ against sustained ischemia/reperfusion (I/R)-induced injury. Protective effects of remote renal preconditioning are well established in the heart, but their mechanisms still remain to be elucidated. Hence, the present study was designed to investigate the possible involvement of erythropoietin in remote renal preconditioning (RRPC)-induced cardioprotection in rats. RRPC was performed by 4 episodes of 5 min renal artery occlusion followed by 5 min reperfusion. Gentamicin (100 mg/kg intraperitoneal) was administered for 6 days for induction of renal failure. Isolated rat hearts were perfused on Langendorff apparatus and were subjected to global ischemia for 30 min ischemia followed by 120 min reperfusion. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were measured in coronary effluent to assess the degree of myocardial injury. Extent of myocardial infarct size and coronary flow rate was also measured. RRPC prevented I/R-induced myocardial injury and produced cardioprotective effects. However, cardioprotective effects of RRPC were not observed in renal failure rats, indicating the protective role of humoral factor was released from functional kidneys. In renal failure rats, exogenous administration of rhEPO (5,000 IU/kg intraperitoneal) with RRPC restored the cardioprotective effects of later. These results implicate that RRPC-induced cardioprotective effects may be mediated through release of erythropoietin from kidney.
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ABSTRACT: Vascular pathologies pose a significant health problem because of their wide prevalence and high impact on the rate of mortality. Blockade of blood flow in major blood vessels leads to ischaemia associated with oxidative stress, where mitochondria act as a major source of reactive oxygen species (ROS). While low levels of ROS perform a necessary function in normal cellular signalling and metabolism, elevated levels under pathological conditions are detrimental both at the cell and organ level. While cellular oxygenation is necessary to maintain tissue viability, a key pathological occurrence when restoring blood flow to ischaemic tissues is the subsequent burst of ROS generation following reoxygenation, resulting in a cascade of ROS-induced ROS release. This oxygen ‘paradox’ is a constraint in clinical practice, that is, the need for rapid and maximal restoration of blood flow while at the same time minimising the harmful impact of reperfusion injury on damaged tissues. Mitochondria play a central role in many signalling pathways, including cardioprotection against ischaemic injury and ROS signalling, thus the main target of any anti-ischaemic protective or post-injury therapeutic strategy should include mitochondria. At present, one of the most effective strategies that provide mitochondrial tolerance to ischaemia is ischaemic preconditioning. In addition, pharmacological preconditioning which mimics intrinsic natural protective mechanisms has proven effective at priming biological mechanisms to confront ischaemic damage. This review will discusses the role of mitochondria in contributing to acute ischaemia-reperfusion (IR) injury, and mechanisms of cardioprotection in respect to mitochondrial signalling pathways.Heart Lung & Circulation 10/2014; · 1.17 Impact Factor
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ABSTRACT: Remote ischemic preconditioning (RIPC) has emerged as an attractive strategy in clinical settings. Despite convincing evidence of the critical role played by circulating humoral mediators, their actual identities remain unknown. In this study, we aimed to identify RIPC-induced humoral mediators using a proteomic approach. and Results Rats were exposed to 10-min limb ischemia followed by 5- (RIPC 5') or 10-min (RIPC 10') reperfusion prior to blood sampling. The control group only underwent blood sampling. Plasma samples were analyzed using surface-enhanced laser desorption and ionization - time of flight - mass spectrometry (SELDI-TOF-MS). Three protein peaks were selected for their significant increase in RIPC 10'. They were identified and confirmed as apolipoprotein A-I (ApoA-I). Additional rats were exposed to myocardial ischemia-reperfusion (I/R) and assigned to one of the following groups RIPC+myocardial infarction (MI) (10-min limb ischemia followed by 10-min reperfusion initiated 20 minutes prior to myocardial I/R), ApoA-I+MI (10 mg/kg ApoA-I injection 10 minutes before myocardial I/R), and MI (no further intervention). In comparison with untreated MI rats, RIPC reduced infarct size (52.2±3.7% in RIPC+MI vs. 64.9±2.6% in MI; p<0.05). Similarly, ApoA-I injection decreased infarct size (50.9±3.8%; p<0.05 vs. MI). RIPC was associated with a plasmatic increase in ApoA-I. Furthermore, ApoA-I injection before myocardial I/R recapitulated the cardioprotection offered by RIPC in rats. This data suggests that ApoA-I may be a protective blood-borne factor involved in the RIPC mechanism.PLoS ONE 09/2013; 8(10):e77211. · 3.53 Impact Factor
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ABSTRACT: Ischemic preconditioning is an intrinsic process in which preconditioning ischemia (ischemia of shorter duration) protects the organs against the subsequent index ischemia (sustained ischemia). Remote ischemic preconditioning (RIPC) is an innovative treatment approach in which interspersed cycles of preconditioning ischemia followed by reperfusion to a remote organ (other than target organ) protect the target organ against index ischemia and reperfusion-induced injury. RIPC of various organs to provide multi-organ salvage became a successful approach in numerous species of animals. Consequently, the concept of RIPC evolved in clinical setups, and provided beneficial effects in alleviating ischemia-reperfusion-induced injury in various remote organs, including myocardium. Clinically, RIPC stimulus is generally delivered by inflating the blood pressure cuff tied on the upper arm 20mm greater than the systolic blood pressure, rendering the forearm ischemic for 5min, followed 5min reperfusion by deflating the cuff. This cycle is repeated for 3-4 consecutive periods to precondition the tissue and improve the survival. The institution of RIPC is beneficial in mitigating myocardial injury in patients undergoing various surgical interventions including coronary artery bypass graft surgery, abdominal aortic aneurysm repair, percutaneous coronary intervention, heart valve surgery, drug-eluting stent implantation, kidney transplantation, elective decompression surgery. The involvement of hypoxia inducible factor-1α (HIF-1α), ATP-sensitive potassium channels, signal transducer and activator of transcription (STAT), matrix metalloproteinases, O-linked β-N-acetylglucosamine (O-GlcNAc) levels, autonomous nervous system in mediating RIPC-induced cardioprotective effects has been explored clinically. However, comprehensive studies are required to elucidate the other possible mechanisms responsible for producing multi-organ protection during RIPC.European Journal of Pharmacology 08/2014; · 2.68 Impact Factor