冠状动脉缺血和再灌注后微血管阻塞:诊断和治疗

冠状动脉阻塞和再灌注后可出现微血管阻塞,导致病情恶化、并发症和死亡率增加。微血管阻塞与心肌肿胀压迫微血管、微血管内皮细胞突向管腔、微栓子脱落、炎症细胞和血小板黏附聚集等有关。冠状动脉造影、心肌红色分级、心肌对比剂超声、磁共振、心电图有助于微血管阻塞的诊断。远端保护器、抗血小板药物、维拉帕米、腺苷等对微血管阻塞可能有治疗作用。     

Nicorandil preserves mitochondrial function during ischemia in perfused rat heart

A possible mechanism for the action of nicorandil on the improvement of energy metabolism of ischemic/reperfused hearts was examined. Perfused rat hearts were subjected to 35-min ischemia/60-min reperfusion. The heart was treated with nicorandil at concentrations of 10 to 100 microM for the last 30-min of pre-ischemia. Nicorandil preserved the mitochondrial oxygen consumption rate during ischemia and attenuated the decrease in mitochondrial function during reperfusion in association with the enhanced post-ischemic recovery of the left ventricular developed pressure. To assess the direct effect on mitochondria, myocardial saponin-skinned bundles were incubated under hypoxic conditions in vitro. Hypoxia-induced decrease in the mitochondrial oxygen consumption rate was attenuated by treatment of the bundles with 100 microM nicorandil. This attenuation was abolished by the combined treatment with the K(ATP) channel blocker, 5-hydroxydecanoate (5-HD). These results suggest that nicorandil is capable of attenuating ischemia/reperfusion injury of isolated perfused hearts through preservation of mitochondrial function during ischemia.     

灯盏花乙素对脑缺血再灌注损伤大鼠肝功能的影响

目的:观察灯盏花乙素对脑缺血再灌损伤大鼠肝功能的影响。方法:大鼠灌胃给药7日后,阻塞大脑中动脉诱导脑缺血再灌损伤,检测大鼠血清和/或肝组织中的一氧化氮、黄嘌呤氧化酶、丙氨酸转氨酶、天冬氨酸转氨酶、丙二醛、抗氧化酶、及细胞色素P-450活性(水平)。结果:灯盏花乙素明显降低(P<0.01)血清中升高的黄嘌呤氧化酶、丙氨酸转氨酶、天冬氨酸转氨酶及肝细织中的丙二醛(P<0.05),升高血清(P<0.01)和肝组织(P<0.05)中降低的一氧化氮并可诱导超氧化物歧化酶(P<0.05)和谷胱甘肽过氧化物酶(P<0.01),除明显降低(P<0.01) CYP3A的活性外,大鼠脑缺血再灌损伤对肝CYP1A1、CYP1A2、CYP2E1的活性没有影响,灯盏花乙素不影响脑缺血再灌损伤大鼠肝CYP的活性。结论:大鼠脑缺血再灌可诱发肝细胞损伤,灯盏花乙素具有保护作用,其作用机制与抗氧化有关。     

Acceleration of recovery of mitochondrial function after coronary reperfusion by various coronary dilating drugs in canine hearts

This study was designed to evaluate whether or not increase in coronary blood flow after reperfusion accelerates the recovery of ischemia-induced mitochondrial damage. Using anesthetized dogs, the left anterior descending coronary artery was occluded for 30 min, followed by 20 min of reperfusion. Five minutes after reperfusion, either physiological saline (n = 9), 0.5 mg/kg of dilazep (n = 7), 0.2 mg/kg of diltiazem (n = 7), or 0.5 mg/kg of nicorandil (n = 8) were administered intravenously. Arterial blood pressure, heart rate, and coronary blood flow were measured throughout the experiment. Twenty minutes after reperfusion, heart mitochondria from normal and reperfused areas were prepared, and mitochondrial function was measured. Significant increase in coronary flow was observed during reperfusion in all drug-treated groups; however, no significant increase was observed in the control group 10 min after reperfusion. Significant hemodynamic changes were not observed in all groups. Mitochondrial function from reperfused areas was recovered significantly in all drug-treated groups, though in the control group mitochondrial dysfunction persisted. Coronary dilative mechanisms of drugs used here differ; however, a similar effect was demonstrated, i.e., administration of a coronary dilator accelerates the recovery of mitochondria after reperfusion. Therefore, it is concluded that coronary flow after reperfusion might be a primary factor in the recovery of ischemia-induced mitochondrial damage.     

羟基积雪草苷对兔心肌缺血再灌注损伤的保护作用

研究羟基积雪草苷(madecassoside，MC)对在体兔缺血再灌注损伤的预防保护作用，并初步探讨MC的作用机制。制备兔心肌缺血再灌注损伤(MIRI)模型；缺血前静脉滴注MC，多时间点检测心电图、血流动力学等指标；用定量组织化学染色方法计算心肌梗死面积；检测血清中酶活性及MDA含量；ELISA法测定血清中C反应蛋白(CRP)含量；TUNEL法检测心肌细胞凋亡；SP法检测细胞凋亡相关蛋白Bcl-2。预先给予MC可明显减小左心及全心心肌梗死面积；对心电图有一定的改善作用；并能明显改善心功能，降低LDH及CK的升高程度。并且，MC可明显降低CRP升高程度；升高SOD酶活性，减少MDA含量；可明显抑制MIRI引起的心肌细胞凋亡，使Bcl-2表达上调。MC对心肌缺血再灌注损伤具有明显的预防和保护作用，作用机制可能与抗脂质过氧化物产生、提高SOD活力、抗炎以及抗心肌细胞凋亡有关。     

DPP4 deficiency preserves cardiac function via GLP-1 signaling in rats subjected to myocardial ischemia/reperfusion

Dipeptidyl peptidase-4 (DPP4) enzyme inhibition has been reported to increase plasma glucagon-like peptide-1 (GLP-1) level for controlling postprandial glucose concentration. Both DPP4 inhibitors and GLP-1 analog have been approved for antihyperglycemic agents. In addition to the insulinotropic effect, GLP-1 signaling was reported to modulate cardiac function. DPP4 inhibition was shown to improve survival rate after myocardial infarction in mice, but the precise mechanism remains unknown. We aimed to compare the cardiovascular responses of ischemia/reperfusion (I/R) between wild-type and DPP4-deficient rats and investigate the underlying mechanism. Rats were subjected to 45 min of coronary artery occlusion, followed by reperfusion for 2 h. Cardiac function was characterized by analyzing pressure–volume loops. As compared to wild-type rats, after I/R, DPP4-deficient rats had better cardiac performance in association with less infarct size and cardiac injury markers (LDH, ANP, and BNP), which could be attenuated by exendin-(9–39), a GLP-1 receptor antagonist. Exendin-(9–39) could diminish the increased phosphorylation levels of myocardial AKT and GSK-3β as well as the higher expression of GLUT4 in post-infarcted DPP4-deficient rats. However, exendin-(9–39) could not completely abrogate the less infarct size in DPP4-deficient rats as compared with that in wild-type rats, implicating the involvement of GLP-1 receptor-independent pathway. In summary, this study demonstrated that the benefit of cardiac protective action against I/R injury was demonstrated in DPP4-deficient rats, which is mediated through both GLP-1 receptor-dependent and receptor-independent mechanisms.     

The effect of inducible nitric oxide synthase inhibitor on microvascular permeability after cerebral ischemia/reperfusion

Our objective was to study the effect of inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) on microvascular permeability after cerebral ischemia/reperfusion (I/R) injury. Cerebral I/R injury was produced by occlusion of both the carotid arteries for 60 min with restitution of blood flow for 60 min. AG (200 mg/kg) was intraperitoneally administrated 5 min before the onset of ischemia and again 5 min before reperfusion. Microvascular permeability was evaluated by 0.75% sodium fluorescein (FINa) extravasation during early 300 s. Cerebral I/R injury increased the permeability of microvessel to fluorescein and the concentration of fluorescein outside of microvessels was significantly higher than that in microvessels after 110 s. However, after AG administration, FINa extravasation appears much faster. From 80 s on, the fluorescence intensity outside is higher. I/R increased microvascular permeability. Nitric oxide derived from iNOS may maintain microvascular permeability at the early stage after I/R.     

Inhibition of HtrA2/Omi ameliorates heart dysfunction following ischemia/reperfusion injury in rat heart in vivo

High temperature requirement A2 (HtrA2)/Omi is a mitochondrial serine protease that is released into the cytosol from mitochondria and in turn promotes caspase activation by proteolyzing inhibitor of apoptosis proteins. Here we asked whether treatment with an HtrA2/Omi inhibitor, 5-[5-(2-nitrophenyl)furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid (UCF-101), restores heart dysfunction following ischemia/reperfusion injury in vivo. Rats underwent a 30-min ischemia by occluding the left anterior descending artery, followed by 24 h reperfusion. UCF-101 (0.75 or 1.5 micromol/kg, i.p.) was administered 10 min before reperfusion. UCF-101 treatment significantly recovered the mean arterial blood pressure and ameliorated contractile dysfunction of the left ventricle 72 h after reperfusion with concomitant reduction of infarct size. Cardio-protection mediated by UCF-101 was correlated with reduced X-linked inhibitor of apoptosis protein (XIAP) degradation and inhibition of Caspase-9, Caspase-3, and Caspase-7 processing. Furthermore, UCF-101 prevented loss of membrane integrity by inhibiting fodrin breakdown in cardiomyocytes. UCF-101-induced cytoprotection was also correlated with reduced Fas ligand expression and inhibition of FLIP degradation following ischemia/reperfusion. These results suggest that UCF-101 rescues cardiomyocytes from ischemia/reperfusion injury by inhibiting XIAP degradation and Fas/Fas-ligand-induced apoptosis, thereby ameliorating ischemia/reperfusion-induced myocardial dysfunction.     

Electrophysiologic effects of bretylium tosylate on the canine heart during coronary artery occlusion and reperfusion

The electrophysiologic and antiarrhythmic actions of bretylium tosylate were studied after acute coronary artery occlusion and reperfusion in pentobarbital-anesthetized dogs. Three groups of animals were studied: Group I (n = 8) served as saline controls, Group II (n = 7) received bretylium tosylate (10 mg/kg i.v.) 60 min prior to coronary artery occlusion, and Group III (n = 5) received bretylium tosylate (30 mg/kg i.v.) in three divided doses over the 24 h prior to coronary artery occlusion. In Groups II and III the effective refractory period of the nonischemic myocardium was not altered by bretylium before or during the occlusion period, nor was it influenced by bretylium during the subsequent reperfusion period. In Group I the effective refractory period of the ischemic myocardium decreased 24 +/- 3.0% after coronary occlusion and increased 12 +/- 3% above the preocclusion level on reperfusion. In Group II the effective refractory period of the ischemic myocardium decreased 28 +/- 3.2% after coronary occlusion but did not overshoot preischemic levels on reperfusion. In Group III the effective refractory period decreased 15 +/- 3.8% following coronary occlusion and did not overshoot preocclusion levels during reperfusion. The ventricular activation times of the normal and ischemic myocardium were not affected by bretylium tosylate during occlusion or reperfusion in Group II or III. Significant reperfusion arrhythmias were observed only in Groups I and II. These data suggest that bretylium tosylate exerts its antiarrhythmic actions in ischemic myocardium by reducing the dispersion of cardiac refractoriness produced by coronary artery occlusion and, consequently, abolishing the abrupt change in cardiac refractoriness that follows coronary artery reperfusion. These antiarrhythmic actions of bretylium are pronounced in the chronically treated group, suggesting an electrophysiologic basis of the delayed antiarrhythmic actions of bretylium.     

Myocardial cytoprotective efficacy of azapropazone in a canine heart model of regional ischemia and reperfusion

The present study assessed the efficacy of azapropazone (AZA) in pentobarbital-anesthetized dogs subjected to 120 min of regional ischemia [left anterior descending coronary artery (LAD) ligation] followed by 5 h of reperfusion. Azapropazone was given 30 min prior to LAD occlusion (100 mg/kg i.v.), 35 min prior to LAD release (50 mg/kg, i.v.), and at 2.5 h postreperfusion (50 mg/kg i.v.). Regional myocardial blood flow (RMBF) and area at risk (AAR) were determined with radiolabeled microspheres. The degree and extent of ischemia (anaerobic metabolism) and necrosis were delineated with 14C-deoxy-2-D-glucose (14C-DG) and 111In-antimyosin, respectively, in control (n = 7) and AZA (n = 7)-treated groups. In mild (60-80% normal RMBF) and moderate (30-60% normal RMBF) flow-restricted areas, AZA resulted in a significant decrease in the degree and extent of ischemia (p less than 0.01) with the limitation of infarct size (p less than 0.01). However, AZA did not produce a significant infarct size limitation in the severe flow-restricted area (0-30% of normal RMBF). The effect of AZA is expressed primarily in moderate flow-restricted myocardium with the subsequent infarct size limitation.     

Protective effects of ghrelin on ischemia/reperfusion injury in the isolated rat heart

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, has been reported to have beneficial effects on cardiac function. The authors used the Langendorff model of ischemia/reperfusion (I/R) injury in isolated rat heart to determine whether ghrelin exerts direct cardioprotective effects. Also, the capacity of ghrelin to bind to sarcolemmal membrane fractions before and after ischemia and reperfusion was examined. Compared with vehicle administration, administration of ghrelin (100-10,000 pM) during the reperfusion period resulted in improvement in coronary flow, heart rate, left ventricular systolic pressure, and left ventricular end-diastolic pressure. Ghrelin also enhanced the rates of left ventricular contraction and relaxation after ischemia following reperfusion. Administration of ghrelin during reperfusion reduced myocardial release of lactate dehydrogenase and myoglobin, indicating protection against cardiomyocyte injury. In addition, ghrelin attenuated the depletion of myocardial ATP resulting from ischemia and reperfusion. A receptor-binding assay demonstrated that maximum binding capacity of ghrelin to sarcolemmal membranes was significantly increased after ischemia and was further increased after I/R. However, Scatchard analysis showed that the affinity of ghrelin for its receptor was not altered. The authors have concluded that administration of ghrelin during reperfusion protects against myocardial I/R injury. The cardioprotective effects are independent of growth hormone release and likely involve binding to cardiovascular receptors, a process that is upregulated during I/R.     

Beneficial effects of streptokinase on left ventricular function after myocardial reoxygenation and reperfusion following global ischemia in the isolated rabbit heart

To determine the effect of streptokinase on the ischemic myocardium independent of its effects on the occluding thrombus, the isolated rabbit heart, perfused with Krebs-Henseleit solution, was subjected to a 45-min period of ischemia--83% reduction in myocardial (perfusion) flow--plus anoxia (95% N2 and 5% CO2), followed by restoration of perfusion and reoxygenation. Streptokinase, 75 or 150 IU/min, was infused starting 15 min before reperfusion and continuing for 30 min after reperfusion. Compared with the control group, streptokinase was associated during reperfusion with a significant dose-dependent greater restoration or smaller depression of ventricular function, dP/dt, and developed pressure. To determine if streptokinase effects were mediated during the ischemic or reperfusion phase, the high streptokinase dose was administered in either the last 30 min of the ischemia or the first 30 min of reperfusion. The improvement in recovery of left ventricular function was primarily in the group having streptokinase administered only during the ischemic period. Thus, streptokinase affects the ischemic myocardium so that there is an acceleration in the recovery of ventricular function or a reduction of the impairment in ventricular function during myocardial reperfusion.     

Comparative effects of azelnidipine and amlodipine on myocardial function and mortality after ischemia/reperfusion in dogs

Effects of azelnidipine were examined and compared with those of amlodipine on stunned myocardium in dogs. The left anterior descending (LAD) coronary artery was ligated for 20 min and subsequently released for 60 min. A vehicle, azelnidipine (0.3 mg/kg), or amlodipine (0.3 or 1 mg/kg) was injected intravenously 20 min before LAD ligation. The heart rate increased after a depressor response in the presence of amlodipine, while it decreased despite a decrease in arterial pressures in the presence of azelnidipine. After reperfusion, the coronary flow (CF) significantly increased in the presence of azelnidipine, but did not change with amlodipine after reperfusion. A positive inotropic effect was observed after treatment with both calcium antagonists. Ischemia significantly decreased the percentage of segment shortening (%SS) in all groups. Treatment with both calcium antagonists significantly increased %SS after reperfusion, although high-energy phosphate levels did not improve in the presence of calcium antagonists 60 min after reperfusion. Mortality with azelnidipine was significantly lower than that with 0.3 mg/kg amlodipine immediately after reperfusion. In conclusion, improvement in myocardial stunning after pretreatment with azelnidipine is associated with an increase in CF after reperfusion. The negative chronotropic action may have contributed to decreased mortality due to reperfusion arrhythmias. Azelnidipine is more beneficial than amlodipine and may provide an additional advantage to patients with angina and hypertension.     

Effect of perhexiline and oxfenicine on myocardial function and metabolism during low-flow ischemia/reperfusion in the isolated rat heart

Perhexiline is a potent prophylactic anti-anginal agent that has been shown to inhibit myocardial utilization of long-chain fatty acids and to inhibit the mitochondrial enzyme carnitine palmitoyltransferase (CPT)-1. We compared the hemodynamic and biochemical effects of perhexiline (0.5 and 2.0 microM) and of another CPT-1 inhibitor, oxfenicine (0.5 mM), in Langendorff-perfused rat hearts subjected to 60 min of low-flow ischemia (95% flow reduction) followed by 30 min of reperfusion. Both perhexiline (2 microM only) and oxfenicine attenuated (p < 0.003, p < 0.0002, respectively) increases in diastolic tension during ischemia, without significant effects on developed tension, or on cardiac function during reperfusion. Myocardial concentrations of long-chain acylcarnitines (LCAC), products of CPT-1 action, were decreased (p < 0.05) by oxfenicine, unaffected by 2 microM perhexiline, and increased slightly by 0.5 microM perhexiline. Perhexiline, but not the active metabolite of oxfenicine, also inhibited cardiac CPT-2 with similar IC50 and Emax, although lower Hill slope, compared with CPT-1. Oxfenicine, but not perhexiline, reduced concentrations of the endogenous CPT-1 inhibitor, malonyl-CoA. Perhexiline, but not oxfenicine, inhibited myocardial release of lactate during normal flow. We conclude that (a) perhexiline protects against diastolic dysfunction during ischemia in this model, independent of major changes in LCAC accumulation and (b) this may result from simultaneous effects of perhexiline on myocardial CPT-1 and CPT-2.     

离体大鼠心肌局部缺血/再灌注模型制备方法的改良

目的改进离体大鼠心肌局部缺血/再灌注损伤模型的制备方法。方法在传统造模的基础上进行改良,采用在结扎线下加一硬塑管打双结的方法,阻断冠状动脉左前降支,局部缺血30min,再灌注180min。分别测定改良组和传统组的心肌梗死面积、漏出液肌酸激酶(CK)活力。结果改良组梗死区/缺血危险区为(45±7)%、变异系数(CV)为15%,CK活力为(382±18)U/ml、CV为5%;传统组梗死区/缺血危险区为(43±11)%、CV为25%,CK活力为(364±30)U/ml、CV为8%。结论改进后的模型制作方法其心肌缺血稳定、可靠,技术难度低,提高了造模的成功率,较传统法具有显著的优越性。     

内皮祖细胞骨移植在缺血再灌注肾损伤中的促血管新生作用

缺血/再灌注(I/R)肾损伤是急性肾衰竭(ARF)的最常见病因.研究证实,内皮祖细胞(EPC)在血管新生和内皮再生,尤其在缺血性疾病治疗方面具有重要意义.最近对EPC在I/R损伤时所发挥的作用进行了探讨,取得了一定进展.本文综述I/R肾损伤后EPC的促血管新生作用.     

Effect of ursodeoxycholic acid on ischemia/reperfusion injury in isolated rat heart

In this study, the effects of ursodeoxycholic acid (UDCA) on ischemia/reperfusion injury were investigated on isolated heart perfusion model. Hearts were perfused with oxygenated Krebs-Henseleit solution (pH 7.4, 37 degrees C) on a Langendorff apparatus. After equilibration, isolated hearts were treated with UDCA 20 to 160 microM or vehicle (0.04% DMSO) for 10 min before the onset of ischemia. After global ischemia (30 min), ischemic hearts were reperfused and allowed to recover for 30 min. The physiological (i.e. heart rate, left ventricular developed pressure, coronary flow, double product and time to contracture formation) and biochemical (lactate dehydrogenase; LDH) parameters were evaluated. In vehicle-treated group, time to contracture formation was 21.4 min during ischemia, LVDP was 18.5 mmHg at the endpoint of reperfusion and LDH activity in total reperfusion effluent was 54.0 U/L. Cardioprotective effects of UDCA against ischemia/reperfusion consisted of a reduced TTC (EC25=97.3 microM), reduced LDH release and enhanced recovery of cardiac contractile function during reperfusion. Especially, the treatments of UDCA 80 and 160 microM significantly increased LVDP and reduced LDH release. Our findings suggest that UDCA ameliorates ischemia/reperfusion-induced myocardial damage.     

Oral administration of geranylgeranylacetone blunts the endothelial dysfunction induced by ischemia and reperfusion in the rat heart

It has been shown that geranylgeranylacetone (GGA) protects heart against ischemia/reperfusion injury via enhanced heat shock protein 72 (HSP72) expression in rats. In the present study, we investigated the protective effect of GGA on ischemia/reperfusion-induced endothelial dysfunction. Rats were given oral GGA (GGA group) or vehicle (CON group), and 24 hours later their hearts were removed and placed in the Langendorff apparatus for 30-minute low-flow ischemia followed by 30-minute reperfusion. GGA improved the postischemic functional recovery (P < 0.01), which was abolished by N-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor). NO production during both ischemia and reperfusion were increased in the GGA group, and the acetylcholine (ACh)-induced (endothelium-dependent) vasodilation, measured as the percentage decrease in coronary perfusion pressure after ischemia/reperfusion (14.9 +/- 1.3%), was preserved as compared with that in the CON group (7.9 +/- 1.4%). LY294002, a phosphatidylinositol 3 (PI3) kinase inhibitor, abolished the protective effects of GGA on endothelial-dependent coronary vasodilation and NO production, whereas Y27632 (Rho kinase inhibitor) increased endothelium-dependent coronary vasodilation and NO production in CON group toward the level seen in GGA group. The amount of adrenomedullin in the coronary effluent at basal condition was lower in the GGA group than in the CON group (P < 0.05), and during both ischemia and reperfusion there was no difference in the amount of adrenomedullin between the GGA and CON groups. In addition, no difference was observed in the amount of endothelin-1 between the GGA and CON groups. These results indicate that GGA attenuates the ischemia/reperfusion-induced coronary endothelial dysfunction, which may contribute to its cardioprotective effect. The PI3 kinase and/or Rho kinase pathways appear to be involved in this process, whereas adrenomedullin and endothelin-1 are not necessary for the GGA-induced cardioprotection.     

多烯康对冠心病患者血管内皮功能的影响

目的研究多烯康对冠心病患者血管内皮功能的影响。方法对36例冠心病患者和30例健康人采用高分辨血管外超声技术测定肱动脉血流介导的舒张功能及硝酸甘油介导的舒张功能,冠心病组服用多烯康12周后检测。结果研究表明冠心病组肱动脉血流介导的舒张及硝酸甘油介导的舒张反应均低于对照组(P<0.01),冠心病组多烯康治疗后较前明显改善(P<0.01)。结论多烯康可改善冠心病患者血管内皮功能。