Bucillamine: a potent thiol donor with multiple clinical applications

Bucillamine has potential to attenuate or prevent damage during myocardial infarction, cardiac surgery and organ transplantation. Bucillamine, a cysteine derivative that contains two donatable thiol groups, is capable of replenishing the thiol group in glutathione, thereby reactivating this endogenous defense against oxidant injury. Bucillamine rapidly enters cells by the same mechanism that normally transports the amino acid cysteine. Bucillamine is a more potent thiol donor than other cysteine derivatives: approximately 16-fold more potent than N-acetylcysteine (Mucomyst(R)) in vivo. In addition bucillamine appears to have additional anti-inflammatory effects unrelated to its antioxidant effect. Oral bucillamine is used clinically in Asia for treatment of rheumatoid arthritis. There is a strong preclinical evidence that parenteral infusion of this agent is efficacious in acute settings characterized by inflammation and oxidative stress. In an investigator-blinded, rigorous intact dog model, consisting of 90 min of coronary artery occlusion and 48 h of reperfusion, bucillamine, given i.v. during the first 3 h of reperfusion, substantially reduced myocardial infarct size. Livers exposed to 24 h of cold ischemia were markedly protected by bucillamine in several transplantation models. In Phase I human studies in normal volunteers, bucillamine at doses up to 25 mg/kg/h i.v. for 3 h elicited no serious toxicity. On the basis of pharmacokinetic analyses of blood levels during these studies it was concluded that bucillamine, infused at i.v. doses > or =10 mg/kg/h for 3 h to humans could be expected to be therapeutically effective in myocardial infarction, organ transplantation and other acute inflammatory syndromes.     

玉郎伞黄酮对大鼠心肌缺血再灌注损伤的保护作用

目的探讨玉郎伞黄酮(YF)对大鼠心肌缺血再灌注(MIR)引起的氧化性应激损伤的保护作用。方法60只SD大鼠,随机分为假手术组,MIR组,生理盐水组和YF低、中、高剂量组,每组大鼠10只,雌雄各半。结扎冠状动脉左前降支30 min后,再灌注60 min,建立MIR模型。用不同剂量YF在结扎前30 min分别做预处理。再灌注结束后采血,测定血浆中天冬氨酸转氨酶(AST)、乳酸脱氢酶(LDH)、乳酸脱氢酶同工酶1(LDH1)、超氧化物歧化酶(SOD)和丙二醛(MDA)的改变,测量心肌梗死面积。结果YF预处理能明显降低血浆中AST、LDH、LDH1和MDA含量,能提高SOD活性,降低心肌梗死面积。结论YF对大鼠MIR氧化性应激损伤具有显著的保护作用。     

银杏叶提取物对大鼠心肌缺血-再灌注损伤的保护作用

目的探讨银杏叶提取物对大鼠心肌缺血-再灌注损伤引起的氧化应激损伤的保护作用。方法将SD大鼠随机分为3组,假手术(Sham)组、缺血-再灌注损伤(MIR)组和银杏叶提取物组,每组10只。建立心肌缺血-再灌注模型。银杏叶提取物在造模前给药14d。再灌注结束后采血,测定丙二醛(MDA)、超氧化物歧化酶(SOD)、天冬氨酸转氨酶(AST)、乳酸脱氢酶(LDH)、乳酸脱氢酶同工酶1(LDH1),测量心肌梗死面积。结果银杏叶提取物能明显降低血浆中AST、LDH、LDH1和MDA的含量,提高SOD活性,减少心肌梗死面积。结论银杏叶提取物对大鼠心肌缺血-再灌注损伤引起的氧化应激损伤的有保护作用。     

金纳多对大鼠心肌缺血再灌注损伤的保护作用

目的观察金纳多对心肌缺血再灌注损伤的保护作用。方法采用在体大鼠结扎冠状动脉前降支10min后,松扎再灌注30min造成心肌缺血再灌注模型,计算心肌梗死范围(MIS),测定血清磷酸肌酸激酶(CK)、乳酸脱氢酶(LDH)、超氧化物歧化酶(SOD)、丙二醛(MDA)含量,观察心律失常发生情况。结果金纳多对心肌缺血10min再灌注损伤30min大鼠,可明显缩小MIS,降低血清CK、LDH活性和MDA含量,提高SOD活性,降低心律失常的发生率。结论金纳多对大鼠心肌缺血再灌注损伤具有保护作用。     

Reduction of ischemic, pharmacological and remote preconditioning effects by an antioxidant N-acetyl cysteine pretreatment in isolated rat heart

The present study was designed to investigate the possible role of free radicals in cardioprotective effects of ischemic, pharmacological and remote preconditioning. Isolated rat heart was perfused on Langendorff apparatus with Kreb's Henseleit solution and subjected to 30 min global ischemia followed by 120 min reperfusion. To assess myocardial injury, coronary effluent was analyzed for lactate dehydrogenase and creatine kinase activity. Myocardial infarct size was estimated using triphenyl tetrazolium chloride staining. Ischemic preconditioning, pharmacological preconditioning (angiotensin II; H2O2), remote aortic preconditioning markedly attenuated I/R induced increase in lactate dehydrogenase and creatine kinase release and myocardial infarct size. Administration of N-Acetyl Cysteine (NAC), in vitro, during ischemic and pharmacological, and in vivo during remote preconditioning attenuated the cardioprotective effects of preconditioning. On the basis of these results, it may be concluded that sub threshold generation of Reactive Oxygen Species (ROS) may activate redox signaling which may be responsible for preconditioning induced cardioprotection.     

Modulatory effect of bucillamine (SA96) on interleukin-1-and/or -2-induced proliferation of T lymphocytes

Bucillamine [SA96:N-(2-mercapto-2-methylpropanoyl)-L-cysteine], a synthetic SH compound, has recently been developed as remission-inducing agent for rheumatoid arthritis (RA), and its clinical usefulness for RA has been proved in Japan. Bucillamine suppressed the mitogen-induced proliferation of murine lymphocytes in vitro. The present study was undertaken to clarify the effect of bucillamine primarily on the release of interleukin (IL)-1 from monocytes and on the proliferation of T cells. Bucillamine significantly inhibited IL-1-induced thymocyte proliferation in a dose-dependent manner. And, bucillamine also inhibited IL-2-induced proliferation at the concentration of 1 x 10(-4) M, but augmented proliferation at the concentration of 1 x 10(-5) M. In contrast, D-penicillamine (an analogous SH compound to bucillamine) did not show any significant effect at similar concentrations.     

Protective effects of caspase-9 and poly(ADP-ribose) polymerase inhibitors on ischemia-reperfusion-induced myocardial injury

The present study was designed to investigate the cardio-protective effect of Ac-LEDH-cmk a selective caspase-9 inhibitor and 5-aminoisoquinolinone a selective Poly (ADP-ribose) polymerase inhibitor on ischemia and reperfusion induced apoptotic and necrotic cell death in rats. Isolated rat hearts were exposed to 30 minutes of global ischemia followed by 120 minutes of reperfusion using Langendorff’s apparatus. Myocardial injury was assessed in the terms of infarct size, release of lactate dehydrogenase, creatine kinase enzymes and apoptotic index was assessed by DNA smearing on agarose gel electrophoresis. Pretreatments with specific inhibitor of caspase-9, Ac-LEHD-cmk (0.07 μM and 0.105 μM), and inhibitor of PARP, 5-aminoisoquinolinone (5 μM and 7.5 μM), significantly attenuated I/R induced increase in infarct size, release of lactate dehydrogenase and creatine kinase in the coronary effluent, and apoptotic index. Therefore, it may be concluded that inhibition of caspase-9 and PARP prevent ischemia and reperfusion-induced activation of apoptotic cascade and necrosis in rat myocardium.     

Fenofibrate attenuates impaired ischemic preconditioning-mediated cardioprotection in the fructose-fed hypertriglyceridemic rat heart

We investigated in this study whether or not the ischemic preconditioning (IPC)-mediated cardioprotective effect against ischemia–reperfusion (I/R) injury exists in the fructose-fed hypertriglyceridemic (HTG) rat heart. Langendorff-perfused normal and fructose-fed (10 %?w/v in drinking water, 8 weeks) HTG rat hearts were subjected to 30-min global ischemia and 120-min reperfusion. IPC protocol included four brief episodes (5 min each) of ischemia and reperfusion. Myocardial infarct size using triphenyltetrazolium chloride staining, markers of cardiac injury such as lactate dehydrogenase (LDH) and creatine kinase (CK-MB) release, coronary flow rate (CFR), and myocardial oxidative stress were assessed. High degree of myocardial I/R injury, by means of significant myocardial infarct size, elevated coronary LDH and CK-MB release, reduced CFR, and high oxidative stress, was noted in the HTG rat heart as compared to the normal rat heart. The IPC-mediated cardioprotection against I/R injury was markedly impaired in the HTG rat heart as compared to the normal rat heart. Interestingly, pharmacological reduction of triglycerides using 8-week treatment protocol with fenofibrate (80 mg/kg/day, p.o.) restored the IPC effect in the HTG rat heart that was blunted by coinfusion, during the IPC reperfusion protocol, of a specific inhibitor of phosphoinositide-3-kinase (PI3-K), wortmannin (100 nM). The IPC failed to protect the HTG rat heart against I/R injury. Fenofibrate treatment reduced high triglycerides in the fructose-fed HTG rat and subsequently restored the cardioprotective effect of IPC.     

Effects of the angiotensin II subtype 1 receptor antagonist losartan on functional recovery of isolated rat hearts undergoing global myocardial ischemia-reperfusion

STUDY OBJECTIVE: To investigate the effects of the angiotensin II subtype 1 receptor (AT1R) antagonist losartan on functional recovery of isolated rat hearts undergoing global myocardial ischemia-reperfusion compared with myocardial protective effects of ischemic preconditioning. DESIGN: Ex vivo experiment using isolated perfused rat heart. SETTING: Academic laboratory. INTERVENTION: Hearts from Sprague-Dawley rats were perfused with oxygenated Krebs-Henseleit buffer and randomized to one of four groups: time control, vehicle, ischemic preconditioning, or losartan. MEASUREMENTS AND MAIN RESULTS: After randomization, hearts underwent 30 minutes of global ischemia followed by 30 minutes of reperfusion. Changes in end-diastolic pressure (EDP), left ventricular developed pressure (LVDP), and infarct size were examined between treatment groups by two-way analysis of variance with repeated measures. Cardiac angiotensin II receptor (ATR) density and infarct size were measured in control hearts and in a subgroup of hearts exposed to ischemia-reperfusion injury. Total ATR density and percentage of myocardial AT1R were increased in hearts exposed to ischemia-reperfusion. Myocardial ischemia-reperfusion injury resulted in a 56% reduction in LVDP from baseline in hearts randomized to vehicle. However, it declined by only 22% and 28% in hearts randomized to ischemic preconditioning and losartan, respectively. Compared with vehicle, both ischemic preconditioning and losartan decreased EDP (ischemic preconditioning 39 +/- 3 mm Hg, losartan 54 +/- 5 mm Hg, vs vehicle 78 +/- 8 mm Hg), and reduced infarct size (ischemic preconditioning 9%, losartan 12%, vs vehicle 36%). CONCLUSION: Treatment of isolated rat hearts with losartan before ischemia-reperfusion injury resulted in significant cardioprotection similar to that observed with ischemic preconditioning.     

Possible mechanism of rottlerin induced modulation of ischemia reperfusion injury in isolated rat hearts

The present study was designed to investigate the modulatory effects of rottlerin on ischemia reperfusion induced myocardial injury. Isolated rat hearts were exposed to 30 min of global ischemia followed by 120 min of reperfusion using Langendorff apparatus. Myocardial injury was assessed in the terms of infarct size, release of lactate dehydrogenase (LDH), creatine kinase (CK) enzymes. Rottlerin, a selective PKCdelta inhibitor, did not modulate ischemia-reperfusion (I/R) induced myocardial injury at low dose (3 microM). However, at moderate dose (6 microM) it significantly produced cardioprotective effects. On the contrary, rottlerin at high dose (12 microM) significantly enhanced I/R induced myocardial injury. However, administration of FR-167653 (1.1 microM, 2.2 microM), a selective p-38 mitogen activated protein kinase (p-38 MAPK) inhibitor, attenuated rottlerin (12 microM) mediated enhancement in I/R induced myocardial injury in a dose dependent manner. Per se administration of FR-167653 (1.1 microM, 2.2 microM) also attenuated I/R induced myocardial injury in a dose dependent manner. Pretreatment with rottlerin (6 microM) did not enhance the cardioprotective effects of FR-167653 (2.2 microM). It may be concluded that rottlerin mediated cardioprotective effects at moderate dose, possible due to inhibition of PKCdelta; while at high dose it enhanced I/R induced myocardial injury which may be attributed to activation of p-38 MAPK.     

银杏内酯A对缺血/再灌注损伤的大鼠心功能的影响

目的探讨银杏内酯A(Ginkgolide A,GA)对离体大鼠心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤的心功能的影响。方法 Langendorff灌注离体大鼠心脏,用停灌复灌的方式制备心肌缺血/再灌注损伤模型,记录左心室收缩峰压(LVSP)、左心室舒张末压(LVEDP)、收缩压和舒张压最大变化速率(±LVdp/dtmax)和心率(HR)的变化,并测定复灌后冠状动脉流出液中LDH和SOD的含量及心肌梗死面积。分离单个细胞进行GA预处理,模拟缺血/再灌注培养后检测心肌细胞存活率和单个心肌细胞的收缩幅度。结果 GA预处理以后,LVSP、-dp/dtmax和HR在复灌10 min时较缺血/再灌注组具有明显的改善(P<0.05),并增加心率,减少LDH的生成,增加SOD的活性,降低心肌梗死面积。经GA预处理的心肌细胞存活率明显提高,10μmol.L-1GA能够明显提高缺血后单个心肌细胞的收缩幅度。结论 GA对缺血/再灌注损伤的心肌具有一定的改善作用。     

丹参对大鼠心肌缺血再灌注损伤保护作用的实验研究

目的：观察丹参对大鼠心肌缺血再灌注损伤的保护作用。方法取健康雄性大鼠150只,根据数字表法随机分为五组：即假手术组、模型组、丹参高剂量组（100 mg／kg）、中剂量组（30 mg／kg）、低剂量组（10 mg／kg）。丹参组分别于术前灌胃给药,每天1次,连续3 d;假手术组和模型组灌以等量0．9％氯化钠注射液。采用在体大鼠结扎冠状动脉30 min然后松扎冠状动脉180 min造心肌缺血再灌注损伤模型。测定心肌梗死范围,测定血清磷酸肌酸激酶（ CK）、乳酸脱氢酶（ LDH）。结果模型组与假手术组相比,心肌梗死范围及血清CK、LDH活性均显著增加（t＝14．382、21．460,均P＜0．05）。不同剂量丹参组均能明显缩小大鼠心肌缺血再灌注损伤的心肌梗死范围,明显降低血清CK,与模型组比较差异均有统计学意义（ t＝7．426、6．891、11．274,均P＜0．05）。不同剂量丹参组均能明显降低血清LDH,与模型组比较差异均有统计学意义（ t＝22．436、10．843、16．252,均P＜0．05）。结论丹参对心肌缺血再灌注大鼠具有抗氧化应激的作用,对大鼠心肌缺血再灌注损伤具有保护作用。     

原花青素对大鼠心肌缺血再灌注损伤的保护作用

目的：观察原花青素（procyanidin,PC）对大鼠心肌缺血再灌注损伤的保护作用，方法：结扎大鼠冠状动脉左前降支（LAD）40min，复灌120min后复制出大鼠心肌缺血再灌注损伤模型，观察PC对大鼠心肌酶学，心梗面积和脂质过氧化的影响。结果：PC能减少心肌细胞磷酸肌酶激酶（CPK）和乳酸脱氢酶（LDH）的释放，明显缩小心肌梗死面积，能显提高大鼠血清和心肌组织中超氧化物歧化酶（SOD）活性，降低心肌和血清脂质过氧化代谢产物丙二醛（MDA）含量，结论：PC对大鼠心肌缺血再灌注损伤有保护作用，其机制可能与清除自由基，抑制脂质过氧化反应有关。     

Role of angiotensin in cardioprotective effect of ischemic preconditioning

This study was designed to investigate the role of angiotensin (Ang II) in the cardioprotective effect of ischemic preconditioning. Isolated perfused rat heart was subjected to global ischemia for 30 min followed by reperfusion for 120 min. Coronary effluent was analyzed for lactate dehydrogenase (LDH) and creatine kinase (CK) release to assess the degree of cardiac injury. Myocardial infarct size was estimated macroscopically by using triphenyl tetrazolium chloride (TTC) staining. Four episodes of ischemic/Ang II preconditioning markedly reduced LDH and CK release in the coronary effluent and decreased myocardial infarct size. The cardioprotective effect of Ang II preconditioning was abolished by CV 11974, AT1-receptor antagonist, whereas no such effect was noted with CV 11974 in ischemic preconditioning. PD 123319, AT2-receptor antagonist, produced no marked effect on Ang II preconditioning and ischemic preconditioning induced reduction in myocardial injury. On the basis of these results, it may be concluded that activation of AT1 receptors may be involved in angiotensin-induced pharmacologic preconditioning. But it may not be involved in the cardioprotective effect of ischemic preconditioning in isolated rat heart.     

Effects of KR-32570, a new sodium hydrogen exchanger inhibitor, on myocardial infarction and arrhythmias induced by ischemia and reperfusion

The present study was performed to evaluate the cardioprotective effects of [5-(2-methoxy-5-chloro-5-phenyl)furan-2-ylcarbonyl]guanidine (KR-32570) in rat and dog models of coronary artery occlusion and reperfusion. In addition, we sought to clarify the efficacy of KR-32570 on reperfusion-induced fatal ventricular arrhythmia. In anesthetized rats subjected to 45-min coronary occlusion and 90-min reperfusion, KR-32570 (i.v. bolus) dose-dependently reduced myocardial infarct size from 58.0% to 50.7%, 35.3%, 33.5% and 27.0% for 0.03, 0.1, 0.3 and 1.0 mg/kg, respectively (P<0.05). In anesthetized beagle dogs that underwent 1.2-h occlusion followed by 3.0-h reperfusion, KR-32570 (3 mg/kg, i.v. bolus) markedly decreased infarct size from 28.9% in vehicle-treated group to 8.0% (P<0.05), and reduced the reperfusion-induced release in creatine kinase isoenzyme MB, lactate dehydrogenase, Troponin-I and glutamic-oxaloacetic transaminase. KR-32570 dose-dependently decreased the incidence of premature ventricular contraction, ventricular tachycardia or ventricular fibrillation induced by ischemia and reperfusion in rats. Similar results were obtained in dogs with reperfusion-induced arrhythmia. In separate experiments to assess the effects of timing of treatment, KR-32570 given 10 min before or at reperfusion in rat models also significantly reduced the myocardial infarct size (40.9% and 46.1%, respectively) compared with vehicle-treated group. In all studies, KR-32570 caused no significant changes in any hemodynamic profiles. Taken together, these results indicate that KR-32570 significantly reduced the myocardial infarction and incidence of arrhythmias induced by ischemia and reperfusion in rats and dogs, without affecting hemodynamic profiles. Thus, it could be potentially useful in the prevention and treatment of myocardial injuries and lethal ventricular arrhythmias.     

Mechanisms mediating the cardioprotective effects of rapamycin in ischaemia-reperfusion injury

1. In the present study, the temporal and concentration-dependent cardioprotective effects of rapamycin against ischaemia-reperfusion (I/R) injury, as well as the underlying mechanisms, were investigated. 2. Rat Langendorff-perfused isolated hearts were exposed to 40 min global ischaemia followed by 120 min reperfusion. Hearts were perfused with different concentrations of rapamycin before and after ischaemia. Myocardial injury was assessed in terms of infarct size and the release of lactate dehydrogenase (LDH) and creatine kinase (CK). The phosphorylation of Akt, extracellular signal-regulated kinase (ERK) 1/2 and endothelial nitric oxide synthase (eNOS) was determined at the end of reperfusion. 3. When administered prior to ischaemia, 25, 50 and 100 nmol/L rapamycin significantly reduced infarct size compared with control (40.1 ± 1.5, 26.3 ± 4.1 and 21.2 ± 3.4 vs 52.5 ± 4.5%, respectively) without affecting the recovery of ventricular function. No reduction in infarct size was observed when 50 nmol/L rapamycin was administered 10 or 120 min into the reperfusion period. 4. Rapamycin (50 nmol/L) enhanced the phosphorylation of Akt kinase but did not affect the phosphorylation of ERK1/2 or eNOS at the end of reperfusion. The cardioprotective effect of rapamycin was blocked by the phosphatidylinositol 3-kinase (Akt) inhibitor LY294002 (15 nmol/L). 5. In conclusion, rapamycin mediates cardioprotection prior to ischaemia and after reperfusion. This protection may involve activation of the phosphatidylinositol 3-kinase pathway.     

Palmatine from Coptidis rhizoma reduces ischemia–reperfusion-mediated acute myocardial injury in the rat

The aim of the present study was to evaluate the protective effect of palmatine, one of active ingredients of Coptidis rhizoma, against myocardial ischemia–reperfusion (I/R) injury is due to its antioxidant and anti-inflammatory action. Adult male rats were subjected to 30 min of ischemia and 6 or 24 h of reperfusion. Rats were randomized to receive vehicle or palmatine 1 h before reperfusion. Infarct size, myocardial function, and the antioxidant enzyme activity, such as malonaldehyde (MDA), lactate dehydrogenase (LDH), creatine phosphokinase (CK), superoxide dismutase (SOD) and catalase (CAT) were measured. Palmatine significantly improved I/R-induced myocardial dysfunction by increasing the values of the first derivative (±dp/dt) of left ventricular pressure and decreased infarct size by 50% (P < 0.01 versus vehicle). As expected, palmatine markedly inhibited the increase of LDH, CK, and MDA contents in I/R rat serum, and it also significantly inhibited the decline of the activity of SOD and CAT in I/R cardiac tissues. In addition, COX-2 and iNOS expression in I/R myocardium was significantly reduced. Interestingly, plamatine increased heme oxygenase (HO)-1 induction in human aortic endothelial cells. We concluded that palmatine protects hearts from I/R injury in rats possibly by reducing oxidative stress and modulating inflammatory mediators.     

氨乙基异硫脲对在体家兔缺血/再灌流心肌损伤及自由基生成的影响(英文)

在家兔心脏冠状动脉结扎缺血/再灌流的损伤型模上,采用电子自旋共振(ESR)技术,直接测定整体家兔心肌缺血/再灌流早期自由基信号。自由基清除剂2-β-氨乙基异硫脲(AET)1.7 mg/kg,结扎前15 miniv,能使缺血30 min/再灌流2 min时,缺血心肌中自由基总浓度(10.6±4.1 nmol/g)明显低于对照组(18.0±2.1 nmol/g),而维拉帕米不能明显降低自由基生成量。AET还能减少再灌流期间脂质过氧化产物丙二醛生成量,降低血浆中CK,LDH的含量,改善ECG变化,从而使心肌梗塞的范围由对照组的31±4％降至12±2％。此外,AET可消除致死性室颤的发生。实验结果提示,自由基在缺血/再灌流损伤发生中起重要作用。AET对缩小心肌梗塞范围,消除室颤的发生具有良好的作用,因此可能是一类防治急性心肌梗塞及溶栓治疗或心脏手术后再灌流引起心律失常的有应用价值的新药。     

Combination of a calcium antagonist, a lipid-peroxidation inhibitor, and an angiotensin AT1-receptor antagonist provides additive myocardial infarct size-limiting effect in pigs.

The calcium antagonist felodipine, the lipid-peroxidation inhibitor H290/51, and the angiotensin II type 1 (AT1)-receptor antagonist candesartan all exert beneficial effects on myocardial ischemia/reperfusion injury. This study was undertaken to test the hypothesis that a combination of these drugs with different pharmacologic properties could exert additive cardioprotective effects. Anesthetized pigs were subjected to 45 min of left anterior descending coronary artery occlusion followed by 240 min of reperfusion. Five groups of pigs were randomly given either 0.65 microM (7 nmol/kg) felodipine, 1.0 microM (3.1 microg/kg) H 290/51, 4.2 microM (20 microg/kg) candesartan, a cocktail of these three drugs, or vehicle (n = 6 for each) for 30 min starting at 5 min before reperfusion by coronary venous retroinfusion, which delivers drugs specifically to the ischemic regions. Systolic segment shortening (%SS) was measured by sonomicrometer. The myocardial area at risk and the final infarct size were determined by Evans blue and 2,3,5-triphenyl tetrazolium chloride staining. The hemodynamics did not change significantly during the study. In the vehicle group, the recovery of coronary flow was not maintained during reperfusion, and it was significantly lower after 240 min of reperfusion than during the preischemic period (p < 0.05). The coronary flow in the drug-treated groups was approximately the same by the end of the reperfusion period as that before the induction of ischemia. In the ischemic myocardium, %SS slightly recovered during reperfusion in the four drug-treated groups, but not in the vehicle group. The infarct size, expressed as a percentage of the myocardial area at risk, was smaller in all four drug-treated groups compared with the vehicle group. The infarct size in the cocktail group was significantly smaller than that in the groups given felodipine, H290/51, or candesartan alone. These results demonstrate that a combination of a calcium antagonist, a lipid-peroxidation inhibitor, and an angiotensin AT1-receptor antagonist has an additive effect on infarct limitation, indicating that combined therapy with agents having different pharmacologic modes of action may provide better cardioprotection than any of the drugs alone. The findings also support the view that reperfusion injury is possibly mediated by a combination of mechanisms.     

Cardioprotective effects of mast cell modulators in ischemia-reperfusion-induced injury in rats

This study was designed to investigate the cardioprotective effects of pharmacological interventions, modulating resident cardiac mast cells, on ischemia-reperfusion-induced injury. Isolated rat hearts were mounted on Langendorff apparatus and subjected to 30-min global ischemia followed by 120-min reperfusion. The extent of mast cell degranulation was assessed by release of mast cell peroxidase (MPO). The release of lactate dehydrogenase (LDH) and creatine kinase (CK) and estimation of infarct size were used to assess the extent of myocardial injury. Left ventricle developed pressure (LVDP) and its derivatives, that is, dp/dt(max) and dp/dt(min), were recorded to evaluate the postischemic recovery of the contractility of heart. Ketotifen (0.1 microM) and low-dose carvedilol (0.1 microM), without beta-blockade activity, attenuated ischemia-reperfusion-induced mast cell degranulation along with the reduction in myocardial injury, suggesting the protective effects of mast cell stabilization during ischemia and reperfusion. Administration of compound 48/80 (1 microg/ml), a specific mast cell degranulating agent, completely degranulated cardiac mast cells before global ischemia. Moreover, it also resulted in the attenuation of ischemia-reperfusion-induced myocardial injury. Decreased release of cytotoxic mediators from already degranulated (empty) mast cells during sustained global ischemia may be responsible for the cardioprotective effects of compound 48/80. Administration of carvedilol or ketotifen after compound 48/80 perfusion did not further enhance the cardioprotective effects, suggesting that the cardiac mast cells may be the common target site for ketotifen, compound 48/80 and low-dose carvedilol.