Myocardial Ischemia-reperfusion Injury In Rabbits Research Articles

Interleukin 8 targeted contrast echocardiography is effective to evaluate myocardial ischemia-reperfusion injury in the rabbits

Interleukin 8 (IL-8) is an important pro-inflammatory cytokine that recruits neutrophil to the areas of inflammation and has been implicated in myocardial ischemia reperfusion injury (MIRI). This study aimed to apply IL-8 targeted myocardial contrast echocardiography (MCE) to evaluate MIRI in rabbits. MCE imaging with IL-8 targeted microbubbles (MBIL-8) and control microbubbles (MBc) was performed in 40 Japanese white rabbits after brief proximal left anterior descending (LAD) partial occlusion for 30 min and subsequent reperfusion for 30 min, 60 min, 120 min and 180 min. Electrocardiogram and regional wall motion were assessed during occlusion and reperfusion. MCE demonstrated that IL-8 level rapidly increased in reperfused myocardial tissue and reached the peak after 120 min of reperfusion and lasted to 180 min of reperfusion. ELISA showed that the tendency of MCE data to change with reperfusion time was the same as that of IL-8 content. Taken together, these results suggest that targeted MCE with IL-8 antibody provides a new approach to noninvasive evaluation of MIRI using ultrasound imaging techniques.

Time-course Study on Left Ventricular Function in a Rabbit Model of Ischemia-reperfusion Injury With Morphine Preconditioning.

To analyze the left ventricular longitudinal function in a rabbit model of myocardial ischemia reperfusion with morphine preconditioning through strain rate imaging and to evaluate the effect of morphine preconditioning. A myocardial ischemia-reperfusion model was induced by occlusion and recanalization of the coronary artery in 40 male New Zealand white rabbits, which were divided into a sham group, morphine group, and vehicle control group. Routine echocardiography data were recorded 1 day before and within 28 days after the operation. Dynamic images were also collected and analyzed off-line using Doppler tissue imaging software. On the first day after the operation, the global and regional systolic functions of the left ventricle in the morphine and vehicle control groups were lower than those in the sham group. After ischemia reperfusion, some of the values of the above-mentioned parameters decreased over time, which was more obvious in the vehicle control group at each examined time point. The current study revealed that detection of changes in regional myocardial function after myocardial ischemia reperfusion by strain rate imaging is objective and accurate. In addition, our results indicated that morphine preconditioning significantly attenuates myocardial ischemia-reperfusion injury in rabbits.

Cardioprotective Effects of HSP72 Administration on Ischemia-Reperfusion Injury

BackgroundAlthough early reperfusion is the most desirable intervention after ischemic myocardial insult, it may add to damage through oxidative stress. ObjectivesThis study investigated the cardioprotective effects of a single intravenous dose of heat shock protein-72 (HSP72) coupled to a single-chain variable fragment (Fv) of monoclonal antibody 3E10 (3E10Fv) in a rabbit ischemia-reperfusion model. The Fv facilitates rapid transport of HSP72 into cells, even with intact membranes. MethodsA left coronary artery occlusion (40 min) reperfusion (3 h) model was used in 31 rabbits. Of these, 12 rabbits received the fusion protein (Fv-HSP72) intravenously. The remaining 19 control rabbits received a molar equivalent of 3E10Fv alone (n = 6), HSP72 alone (n = 6), or phosphate-buffered saline (n = 7). Serial echocardiographic examinations were performed to assess left ventricular function before and after reperfusion. Micro–single-photon emission computed tomography imaging of 99mTc-labeled annexin-V was performed with micro–computed tomography scanning to characterize apoptotic damage in vivo, followed by gamma counting of the excised myocardial specimens to quantify cell death. Histopathological characterization of the myocardial tissue and sequential cardiac troponin I measurements were also undertaken. ResultsMyocardial annexin-V uptake was 43% lower in the area at risk (p = 0.0003) in Fv-HSP72–treated rabbits compared with control animals receiving HSP72 or 3E10Fv alone. During reperfusion, troponin I release was 42% lower and the echocardiographic left ventricular ejection fraction 27% higher in the Fv-HSP72–treated group compared with control animals. Histopathological analyses confirmed penetration of 3E10Fv-containing molecules into cardiomyocytes in vivo, and treatment with Fv-HSP72 showed fewer apoptotic nuclei compared with control rabbits. ConclusionsSingle-dose administration of Fv-HSP72 fusion protein at the time of reperfusion reduced myocardial apoptosis by almost one-half and improved left ventricular functional recovery after myocardial ischemia-reperfusion injury in rabbits. It might have potential to serve as an adjunct to early reperfusion in the management of myocardial infarction.

Protective effects of morphine preconditioning in delayed phase on myocardial ischemia-reperfusion injury in rabbits.

The aim of this study was to investigate the protective mechanisms of delayed-phase morphine preconditioning on myocardial ischemia-reperfusion injury. Thirty healthy male New Zealand white rabbits were randomly divided into three groups: a sham operation group (C), ischemia-reperfusion group (I/R), and delayed-phase morphine preconditioning group (M) (N = 10/group). Rabbits in the C group received thoracotomy for 160 min. Rabbits in the I/R group received left artery blockage for 40 min and reperfusion for 120 min. Rabbits in the M group received 1.0 mg/kg intravenous morphine 24 h prior to the identical treatment as the rabbits in the I/R group. In each group, the interleukin (IL)-10 and tumor necrosis factor (TNF)-α levels were detected at five time points: 20 min before the left coronary artery blockage (T1), 20 and 40 min after the left coronary artery blockage (T2 and T3, respectively), and 1 and 2 h after the myocardial reperfusion (T4 and T5, respectively). After reperfusion, the infarction size was measured with Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) staining. Compared with the C group, serum IL-10 and TNF-α concentrations increased in the I/R and M groups; the difference was significant (P < 0.05). When compared with the I/R group, the IL-10 concentrations in the M group were significantly increased (P < 0.05), but the infarction size and TNF-α concentrations were significantly decreased (P < 0.05). These results suggested that delayed-phase morphine preconditioning might achieve myocardial protection through the regulation and balance of inflammatory cytokines.

Effect of trapidil in myocardial ischemia-reperfusion injury in rabbit.

Objectives:To evaluate the cardioprotective effects of trapidil on myocardial ischemia-reperfusion injury (MIRI) in rabbits.Materials and Methods:Rabbits were subjected to 40 min of myocardial ischemia followed by 120 min of reperfusion. Blood for superoxide dismutase (SOD) and malondialdehyde (MDA) were estimated. At the end of reperfusion, the rabbits were sacrificed and the hearts were isolated for histological examination. An apoptotic index (AI) was determined using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end-labeling (TUNEL) method. The expression of apoptosis-related proteins Bax and Bcl-2 was analyzed using immunohistochemistry. Statistical analyses were performed by one-way analysis of variance (ANOVA), P < 0.05 considered statistically significantResults:Trapidil caused a significant (P < 0.05) increase in SOD activity, as decreased MDA levels and significantly (P < 0.05) reduced the expression of Bax as compared with the ischemia-reperfusion (IR) control group.Conclusion:Trapidil may attenuate the myocardial damage produced by IR injury and offer potential cardioprotective action.

Effect of emulsified isoflurane preconditioning on myocardial ischemia-reperfusion injury in rabbits

Objective To evaluate the effect of emulsified isoflurane preconditioning on myocardial iachemia-reperfusion (I/R) injury in rabbits.Methods Thixty-two male New Zealand white rabbits weighing 2.5-3.0 kg were randomly divided into 4 groups(n=8 each):group Ⅰ I/R;group Ⅱ isoflurane preconditioning (group Ⅰ);group Ⅲ emulsified isoflurane preconditioning (group EI) and group Ⅳ intralipid (group INT).Myocardial I/R was induced by 30 min occlusion of left anterior descending branch of coronary artery followed by 180 min of reperfusion.After 30 min of post-preparation equilibration.the animal inhaled 3%isoflurane for 30 min followed by 15 min washout in group Ⅰ(group Ⅱ);8% emulsified isoflurane 8-10 ml was injected iv at 1 ml/s followed by continuous infusion at 6-8 ml·kg-1·h-1,maintaining end-tidal isoflurane concentration at 1.28% for 30 min in group EI (groupⅢ);30% intralipid 9 ml was injected iv at 1 ml/s fullowed by continuous infusion at 7 ml·kg-1·h-1 for 30 min in group INT (group IV).HR and BP were monitored and recorded at 30 min of post-preparatory equilibration(T0),before ischemia(T1),at the beginning of ischemia(T2),at 30 min ofischemia(T3),60,120 and 180 min of reperfnsion(T4,5,6).HR-SP product (RPP) was calculated.Infarct size (IS) was determined by TIC staining.Blood samples were taken from carotid artery at T6 for determination of serum CK and LDH activities and IL-6 and IL-10 concentrations.Results HR,MAP and RPP were decreasing during T2-6, but there was no significant difference in HR, MAP and RPP among the 4 groups.The infarct size was signigicantly smaller, serum CK and LDH activities and IL-6 concentration were significantly lower while serum IL-10 concentration was significantly higher in group I and EI than in group I/R and INT.Conclusion Emulsified isoflurane preconditioning can attenuate myocardial I/R injury by inhibiting inflammatory response. Key words: Isoflurane; Fat emulsions, intravenous; Ischemic preconditioning; Myocardial reperfusion injury

Effect of morphine postconditioning on myocardial ischemia-reperfusion injury in rabbits

To investigate the protective effects of morphine postconditioning on myocardial ischemia-reperfusion (I/R)injury and the potential mechanisms in rabbits. Thirty-two New Zealand male white rabbits were randomly assigned into 4 groups: Group 1 (Sham), Group 2 (I/R), Group 3 (ischemic postconditioning), Group 4 (ischemia and morphine postconditioning). Group 1 was perfused for 160 min; Group 2 underwent 40 min ischemia and 120 min reperfusion; Group 3 underwent three cycles of 30 s reperfusion and 30 s left anterior descending coronary artery re-occlusion immediately after 40 min ischemia and before 120 min reperfusion; Group 4 was given morphine 1.0 mg/kg immediately after 40 min ischemia in 1 min and before 120 min reperfusion. Blood samples were taken from arterial line at 20 min before occlusion, 20 min after occlusion, 40 min after occlusion, 1 h after reperfusion and 2 h after reperfusion for determination of the plasma levels of cardiac troponin I (cTnI). At the end of the reperfusion, infarct size (IS) and area at risk were defined by Evans and TTC staining. Plasma SOD activity and MDA were determined at the end of reperfusion. The levels of cTnI were significantly lower during reperfusion in the two postconditioning groups than those in I/R group. The plasma MDA content was significantly lower and SOD activity was significantly higher in the two postconditioning groups than those in I/R group, but there was no difference between two postconditioning groups. Morphine significantly reduced infarct size of the left ventricular area at risk as compared with I/R group (P<0.05). Morphine postconditioning is as effective as ischemic postconditioning in the protection of myocardium against I/R injury in rabbits. Decrease in oxygen free radicals and increased antioxidant activity might be involved in its mechanism.

Role of opioid receptors in protective effects of isoflurane- induced delayed preconditioning against myocardial ischemia-reperfusion injury in rabbits

Objective To investigate the role of opioid receptors in the protective effects of isoflurane-induced delayed preconditioning against myocardial ischemia-reperfusion (I/R) injury in rabbits. Methods Forty male New Zealand white rabbits weighing 2.0-2.5 kg were randomly assigned into 4 groups ( n = 10 each) : group I sham operation (S); group II I/R; group Ⅲ isoflurane + I/R (Iso) and group IV Iso + naloxone + I/R (Nal). Myocardial I/R was induced by 40 min occlusion of left anterior descending branch (LAD) of coronary artery followed by 120 min reperfusion. In group Ⅲ (Iso) 2% isoflurane in 100% O2 was inhaled for 2 h and I/R was produced 24 h later. In group IV (Nal) naloxone 6 mg/kg was given iv 10 min before 2 h of 2% isoflurane inhalation and I/R was produced 24 h later. At the end of 120 min reperfusion, infarct size (IS) and area at risk (AAR) were determined by Evan's blue and TTC staining. Myocardial ultrastructure was examined by electron microscopy. The phosphorylated p38MAPK protein expression in myocardium was determined by Western blot. Results The IS was significantly smaller in group Iso ( Ⅲ ) ( 19.7% ± 2.8%) than in I/R group ( II ) (37.8% ±1.7%) (P<0.05). The phosphorylated p38MAPK protein expression in myocardium was significantly lower in group Iso than in group I/R. Microscopic examination showed less myocardial damage in Iso group than in group I/R. The protective effects of delayed preconditioning by isoflurane was prevented by naloxone pretreatment. ConclusionOpioid receptors may be involved in the protective effects of delayed preconditioning by isoflurane against myocardial I/R injury. Key words: Receptors, opioid; Isoflurane; Ischemic preconditioning, myocardial; Myocardial reperfusion injury

Effects of Quercetin on Gene and Protein Expression of NOX and NOS after Myocardial Ischemia and Reperfusion in Rabbit

Previous studies have suggested that reactive oxygen species (ROS), endothelial nitric oxide synthase (eNOS), and inducible nitric oxide synthase (iNOS) are involved in the pathophysiology of myocardial ischemia-reperfusion injury (MIRI). The NOX family of NADPH oxidases share the capacity to generate superoxide and ROS. Several studies have demonstrated that quercetin possesses a protective effect against MIRI. Our aim is to investigate the effects of quercetin on NOX2, eNOS, and iNOS after MIRI in rabbits. New Zealand rabbits were subjected to 30 min of myocardial ischemia followed by 12 h of reperfusion. They were then randomly assigned to four experimental groups: control, I/R (ischemia/reperfusion), quercetin (Que), I/R + Que. Gene and protein expression of NOX2, eNOS, and iNOS were compared. Both in real-time PCR and in the Western blotting studies, myocardial ischemia-reperfusion-induced NOX2 and iNOS expression were enhanced (P < 0.01) but eNOS mRNA and protein expression in I/R hearts were not significantly different from those in control (P < 0.01). Administration of quercetin reduced NOX2, eNOS, and iNOS mRNA and protein expression both in control and in I/R heart (P < 0.01). Gene and protein expression of NOX2 and iNOS were increased after MIRI. Quercetin not only inhibited myocardial ischemia-reperfusion-induced NOX2 and iNOS mRNA and protein expression but also inhibited eNOS mRNA and protein expression.

Effect of desflurane-induced preconditioning following ischemia-reperfusion on nitric oxide release in rabbits

Nitric oxide (NO) is the mediator of ischemic preconditioning against myocardial infarction. Desflurane produces anesthetic preconditioning to protect the myocardium against infarction. In the model of myocardial ischemia-reperfusion injury in rabbits, we evaluated desflurane-induced ischemic preconditioning and studied its mechanism of NO synthesis. Thirty-two male adult New Zealand white rabbits were anesthetized with intravenous (IV) 30 mg/kg pentobarbital followed by 5 mg/kg/hr infusion. All rabbits were subjected to 30 minutes (min) long lasting left anterior descending coronary artery (LAD) occlusion and three hours (hr) of subsequent reperfusion. Before LAD occlusion, the rabbits were randomly allocated into four groups for preconditioning treatment (eight for each group). The control group did not receive any preconditioning treatment. The desflurane group received inhaled desflurane 1.0 MAC (minimal end-tidal alveolar concentration) for 30 min that was followed by a 15 min washout period. The L-NAME-desflurane group received L-NAME (N G-nitro-L-arginine methyl ester; non-selective Nitric Oxide Synthetase (NOS) inhibitor) 1 mg/kg IV 15 min before 1.0 MAC inhaled desflurane for 30 min. The L-NAME group received L-NAME 1 mg/kg IV. Infarct volume, ventricular arrhythmia, plasma lactate dehydrogenase (LDH), creatine kinase (CK) activity and myocardial perfusion were recorded simultaneously. We have found that hemodynamic values of the coronary blood flow before, during, and after LAD occlusion were not significantly different among these four groups. For the myocardial ischemia-reperfusion injury animals, the infarction size (mean ± SEM) in the desflurane group was significantly reduced to 18 ± 3% in the area at risk as compared with 42 ± 7% in the control group, 35 ± 6 in the L-NAME group, and 34 ± 4% in the L-NAME-desflurane group. The plasma LDH, CK levels, and duration of ventricular arrhythmia were also significantly decreased in the desflurane group during ischemia-reperfusion injury. Our results indicate that desflurane is an anesthetic preconditioning agent, which could protect the myocardium against the ischemia-reperfusion injury. This beneficial effect of desflurane on the ischemic preconditioning is probably through NO release since L-NAME abrogates the desflurane preconditioning effect.