A protective effect of coenzyme Q10 on ischemia and reperfusion of the isolated perfused rat heart

Experiments were undertaken to determine if pretreating the animal with coenzyme Q₁₀ (CoQ) protected the cardiac muscle of the isolated perfused heart which was exposed to global ischemia for 30 min and then reperfusion.Two hours after the intramuscular (20 mg/kg) and intraperitoneal (10 mg/kg) injections of CoQ or vehicle alone the hearts were excised and perfused by Langendorff's technique. In the vehicle-pretreated group, ischemia caused a precipitous decline of the contractile tension development, an elevation of the resting tension and a severe contracture. During the substrate-free reperfusion for 30 min, there was a small decrease in the magnitude (25%) of the contracture, and, yet, no tension development. In the additional reperfusion with glucose as the substrate for 30 min, the tension development was slightly (11%) recovered. Tissue ATP and total adenine nucleotide contents at the end of the glucosereperfusion markedly decreased. Although pretreatment with CoQ had no effect on the onset and progression of ischemic contracture, it facilitated the recovery of mechanical performance. Cardiac stores of both ATP and total adenine nucleotide in CoQ-pretreated reperfused hearts were significantly (P < 0.01) higher than those in vehicle-pretreated group. There was a direct relation between the extent of the recovery of mechanical performance and tissue ATP content.It was suggested that exogenous CoQ protected the cardiac muscle from the deterioration of mechanical function of ischemia and recovery. Better mechanical function of CoQ-pretreated heart was attributable to better resynthesis of ATP presumably due to lesser loss of adenine nucleotide pool from the cardiac cells.     

仙茅多糖对阿霉素致小鼠心肌损伤的保护作用

目的探讨仙茅多糖(COP)对阿霉素(ADM)诱导小鼠中毒性心肌损伤的保护作用及其机制。方法选用ADM建立小鼠心肌损伤模型。测定血清肌酸激酶(CK)、乳酸脱氢酶(LDH)、谷草转氨酶(GOT)和一氧化氮合酶(NOS)、超氧化物歧化酶(SOD)活力、丙二醛(MDA)含量、心肌SOD、MDA等生化指标,并观察心肌结构变化。结果 ADM可致血清CK、LDH、GOT和NOS活力升高(P<0.01),同时血清和心肌SOD活力下降而MDA含量升高(P<0.01)。COP能降低血清CK、LDH、GOT和NOS活力(P<0.05或P<0.01),增加心肌SOD活力和降低MDA含量(P<0.05或P<0.01)。光镜也证实了COP的保护作用。结论 COP对ADM引起的心肌损伤具有明显保护作用,其作用机制可能与抗自由基、抑制脂质过氧化作用有关。     

A protective effect of verapamil on the calcium paradox in the isolated perfused rat heart

Experiments were undertaken to examine whether and how verapamil, one of the well known slow-channel calcium-antagonists, protected cardiac muscles against the calcium paradox in isolated perfused rat hearts.Following a 5-min perfusion with calcium-free buffer at pressure of 80 cm H₂O (high flow) and 40 cm H₂O (low flow), severe and mild calcium paradoxical injuries were produced, respectively, by reperfusion with buffer containing 2.5 mm of calcium for 10 min at 80 cm H₂O. When verapamil (1 mg/l) was added to the perfusion medium during both the calcium depletion and repletion periods, a marked protective effect on the mild calcium paradox was observed, evidenced by a higher recovery in the contractility, an about 50% reduction in development of the contracture, and almost complete prevention in release of creatine kinase, an inhibition of tissue calcium accumulation, and much larger tissue stores of high energy phosphates; whereas no protective effect was observed on the severe calcium paradox. In the mild calcium paradox, administration of verapamil up to 2 min after the readmission of calcium was sufficient for protection against the calcium paradox.It was suggested that verapamil could substantially protect heart muscles from injuries associated with the calcium paradox probably due to an inhibition of sudden calcium influx into the cardiac cells in early calcium repletion period.     

尼克酰胺腺嘌呤二核苷酸对阿霉素所致大鼠心肌损伤的保护作用

目的观察尼克酰胺腺嘌呤二核苷酸(NADH)对阿霉素(ADR)损伤的大鼠心肌保护作用。方法将60只雄性健康Wistar大鼠随机分为ADR组、NADH组、ADR NADH组及对照组。在实验第8周处死大鼠.光镜下观察心肌形态结构及病理改变;用生化方法测定大鼠心肌组织、心肌细胞线粒体中谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活性及丙二醛(MDA)水平。结果光镜下ADR NADH组大鼠心肌组织损伤程度较ADR组明显减轻;从心肌组织GSH-Px、SOD活性可以看出,与ADR组[(3.97±1.11.15.63±3.79)kU/g Pr]比较,ADR NADH组[(5.88±0.97,49.27±4.22)kU/g Pr]明显增高,二者比较差异有统计学意义(q=7.22、32.18,P<0.01);心肌组织MDA水平,ADR组[(4.55±1.51)μmoI/g Pr]明显高于ADR NADH组[(3.64±0.75)μmoL/g Pr],二者比较差异有统计学意义(q=8.48,P<0.01)。结论NADH对阿霉素性心肌损伤有一定的保护作用,这种保护作用可能主要与NADH提高受损心肌细胞抗氧化能力有关。     

Effects of Adriamycin on rat heart cells in culture: Increased accumulation and nucleoli fragmentation in cardiac muscle v. non-muscle cells

Primary cultures from neonatal rat hearts consist of morphologically distinguishable cardiac muscle and non-muscle cells. The relative fluorescence intensity and nucleolar effects of Adriamycin (ADR) have been studied in these different cell types by fluorescence and phase-contrast microscopy. In cultures exposed to ADR (10 μg/ml) for 30 min, or continuously for 24 h, the intensity of drug-specific fluorescence was significantly greater in the nuclei of muscle, as compared to non-muscle cells. Consistent with these differences in cytofluorescence, nucleolar fragmentation was observed in muscle cells 24 h after a 30-min exposure to ADR, whereas non-muscle cell nucleoli remained intact. With N-trifluoroacetyladriamycin-14-valerate (AD 32), a potent ADR analog, fluorescence was observed in the cytoplasm of both muscle and non-muscle cells; no difference in the intensity of fluorescence between these two cell types was detected. Based on these observations, we believe that drug-induced nucleolar fragmentation in cardiac muscle cells results from higher ADR levels than those achieved in non-muscle cells, and that these differences may have relevance with respect to anthracycline-induced cardiotoxicity in vivo.     

Protective effect of coenzyme Q10 on thyrotoxic heart in rabbits

Summary An excess of thyroid hormone is known to produce cardiac dysfunction and failure, i.e., thyrotoxic heart. We studied the protective effect of coenzyme Q10 (CoQ10) on the thyrotoxic heart in 29 rabbits. A group treated with 1-thyroxine sodium salt (T₄; 167 µg/kg) for 3 weeks showed marked decreases in the myocardial content of norepinephrine (NE) and ATP (0.5±0.2 µg/g wet weight,P<0.05 and 31.1±2.6 nmol/mg protein,P<0.05, respectively) as compared with a group treated with CoQ10 solvent (2 ml/kg) for 3 weeks (1.1±0.1 µg/g wet weight and 45.7±4.7 nmol/mg protein). The mitochondrial Ca²⁺ content of the T₄ group showed significant increases (21.3 ± 0.6 nmol/mg protein,P<0.05) compared with the solvent group (18.2±0.8 nmol/mg protein), while the total tissue Ca²⁺ content of the T₄ group was unchanged compared with the solvent group. These biochemical derangements suggest that T₄-treated rabbits were in a state of cardiac dysfunction. In contrast, a group which was assigned to concomitant treatment of T₄ and CoQ10 (5 mg/kg) for 3 weeks showed no reductions in NE and ATP (0.9±0.2 µg/g wet weight and 44.6±1.9 nmol/mg protein, respectively) and protected an increase in the mitochondrial Ca²⁺ content (18.2±1.2 nmol/mg protein). A group treated with CoQ10 (5 mg/kg) for 3 weeks showed no changes in myocardial NE, ATP, and Ca²⁺ content in the mitochondria. These results suggest that exogenously administered CoQ10 may protect against biochemical derangements in the thyrotoxic heart.     

Clinical experience of coenzyme Q10 to enhance intraoperative myocardial protection in coronary artery revascularization

Seventy-eight patients undergoing coronary artery bypass grafting (CABG) were compared retrospectively to evaluate whether pretreatment with coenzyme Q₁₀ (CoQ) is effective in preventing left ventricular depression in early reperfusion following CABG. CoQ (5 mg/kg, intravenously) was given to 60 patients, 2 hours prior to the onset of cardiopulmonary bypass (CPB). CABG was performed using saphenous vein under CPB associated with cold cardioplegia in the standard fashion. Heart rate, mean arterial pressure, and cardiac index showed no significant difference between the CoQ and control groups. However, left ventricular stroke work index was significantly elevated at 6 and 10 hours of reperfusion following CABG in the CoQ-treated group compared with the controls. Serum MB-CK was lower at 0 and 6 hours of reperfusion in the CoQ group compared with the controls. These results suggest that pretreatment with intravenous CoQ is effective in preventing left ventricular depression in early reperfusion and in minimizing myocardial cellular injury during CABG followed by reperfusion.     

The effect of Ligustrum delavayanum on isolated perfused rat heart

BACKGROUND:

Extract of ligustrum leaves (Ligustrum delavayanum Hariot [Oleaceae]) is well known in traditional Chinese medicine. One of the active components, oleuropein, displays vasodilating and hypotensive effects.

OBJECTIVE:

To analyze the effect of 0.008% lyophilized extract of ligustrum dissolved in 0.5% ethanol on heart function.

ANIMALS AND METHODS:

Experiments were done on isolated rat hearts perfused by the Langendorff method in control conditions and during ischemic-reperfusion injury.

RESULTS:

Application of ligustrum induced positive inotropic and vasodilating effects in spontaneously beating hearts. Pretreatment of the hearts with ligustrum reduced left ventricular diastolic pressure measured during reperfusion and improved left ventricular contraction compared with hearts without any pretreatment. Ligustrum significantly suppressed the incidence and duration of cardiac reperfusion arrhythmias, expressed as G-score, from 7.40±0.58 in nontreated rats to 1.97±0.50.

DISCUSSION:

Application of ligustrum or ethanol alone induced changes in coordination between atria and ventricles during ischemia-reperfusion injury. The ‘g-score’, a new parameter summing the incidence and duration of atrioventricular blocks, atrioventricular dissociation and cardiac arrest, is introduced. The g-scores with ligustrum pretreatment were higher during ischemia than during reperfusion. Ethanol significantly depressed myocardial contractility and coronary flow, and nonsignificantly decreased heart rate of isolated rat hearts. Electrical changes observed during coronary reperfusion in the presence of ethanol were accompanied by deterioration of contractile function.

CONCLUSIONS:

Ligustrum had a significant protective effect on rat myocardium against ischemic-reperfusion injury. Ethanol partially attenuated the protective effect of ligustrum.     

A stereological analysis of the effect of adriamycin on the ultrastructure of rat myocardial cells in culture

Adriamycin is an effective anti-cancer agent which produces a dose-dependent, irreversible cardiomyopathy of unknown etiology in a significant number of cancer patients. The effect of adriamycin on the ultrastructure of cultured mammalian myocardial cells was examined with light and electron microscope stereological analysis. Cell surface/cell volume, nuclear volume/cellular volume, and nuclear volume/sarcoplasmic volume ratios did not change after adriamycin treatment, showing that the cell volume and sarcoplasm volume were not altered. The nuclear surface area relative to both the nuclear volume and cellular volume was greater in adriamycin-treated cells, implying increased nuclear pleomorphism. The percent of myocardial sarcoplasm occupied by the mitochondria increased very significantly subsequent to adriamycin treatment. That the mitochondria increased in size was indicated by the unchanged mitochondrial surface/cell volume ratio and the decrease in the mitochondrial surface/volume ratio. A significant decrease in glycogen content after exposure to adriamycin as revealed by electron microscope stereological analysis was also observed with the light microscope. Subsequent to adriamycin treatment a small fraction of the cells died and detached from the plate.     

辅酶Q_(10)对移植心脏再灌注损伤保护的实验研究

本文以大鼠腹腔心脏移植为模型,实验组在心脏移植前注入辅酶Q_(10)(CoQ_(10)),术后测定供心组织:1.实验组超氧化物岐化酶(SOD),谷胱甘肽过氧化物酶(GSH-Px)均高于对照组(P<0.01,P<0.05),过氧化脂质(LPO)明显低于对照组(P<0.01),2.超微结构显示实验组的改变较对照组明显减轻.提示:心脏移植前应用CoQ_(10)可明显降低供心氧自由基产生,同时增强机体内源抗氧化酶活性,保护心肌结构,减轻移植心肌组织的损伤.     

Effect of beta-blocker on metabolism and contraction of doxorubicin-induced cardiotoxicity in the isolated perfused rabbit heart

The effect of beta-blocker (propranolol) on the metabolism and contraction of doxorubicin-induced cardiomyopathy during pacing or ischemia was examined by the phosphorus 31-nuclear magnetic resonance (31 P-NMR) in Langendorff hearts of chronically treated rabbits after cumulative doses of 16 mg doxorubicin/kg. After 8 weeks of doxorubicin treatment, beta-blocker (propranolol) was given orally over a period of 2 weeks for a cumulative dose of 1.4 mg/kg. Isolated hearts were paced at higher heart rates, or hearts were perfused on low flow. Adenosine triphosphate (ATP), creatine phosphate (PCr), inorganic phosphate (Pi), pH, left ventricular systolic developed pressure (LVDev P), and coronary flow were measured. The hearts were divided into three experimental groups: Group I consisted of controls, Group II consisted of doxorubicin treatment, and Group III consisted of doxorubicin treatment with propranolol. Group II showed a significant decrease of ATP during pacing (48 +/- 2%) and during low flow (61 +/- 6%) compared with Group I (86 +/- 9% at pacing, 94 +/- 6% on low flow). But Group III showed a significantly marked improvement of ATP during pacing (95 +/- 10%) and during low flow (83 +/- 3%) compared with Group II. Furthermore, Group II showed a significant decrease of LVDev P during pacing (69 +/- 6 mm Hg) and during low flow (63 +/- 3 mm Hg) compared with Group I (101 +/- 5 mm Hg at pacing, 95 +/- 9 mm Hg on low flow). But Group III showed a significantly marked improvement of LVDev P during pacing (93 +/- 5 mm Hg) and during low flow (83 +/- 14 mm Hg) compared with Group II. In conclusion, propranolol had a significant beneficial effect on metabolism and contraction during high-energy demand and during low oxygen supply of doxorubicin cardiomyopathy.     

The effect of heart rate on the termination of electrically induced ventricular fibrillation in the isolated perfused rat heart

Ventricular fibrillation (VF) which is normally sustained in large animals and humans, is transient in small animals. The purpose of the present study was to evaluate the possible effect of changing cardiac rate on spontaneous ventricular defibrillation. In isolated perfused rat heart, VF was electrically induced during normal spontaneous rhythm of the heart at normal rate and at various ventricular pacing rates. It was found that: 1) Electrically induced VF in isolated perfused, non-ischemic rat heart spontaneously terminated in 88% of the hearts; 2) Ventricular pacing rhythm of spontaneous rate plus 10% caused VF to be sustained in 26% of the hearts (which defibrillated spontaneously during normal rates); 3) Ventricular pacing at 200% of the basic rate led to sustained VF in about half the VF episodes (14 out of 33, p less than 0.005). In the remainder, which defibrillated spontaneously, a sustained VF could be achieved by further increase in ventricular pacing rate; 4) Slow pacing rate, as a result of the surgical production of atrioventricular (A-V) block, enhanced the probability of spontaneous defibrillation (21 of 21 episodes after slow pacing vs 24 of 34 episodes following pacing at previous normal sinus rhythm, p less than 0.05). Selective modulation of conduction velocity, refractory period or both, achieved by changes in ventricular pacing rate was assumed to play an important role in determining whether electrically-induced VF would be transient or sustained.     

The mechanism of protective effect of diltiazem on reperfusion-induced arrhythmias in isolated rat heart

This investigation was undertaken to define the mechanism by which diltiazem protects against life-threatening, reperfusion-induced arrhythmias. Using an isolated retrogressively perfused rat heart preparation with transient coronary artery occlusion, we compared the effects of diltiazem in its active form (d-cis) to its stereo-isomer (1-cis). Pre-ischemic administration of d-diltiazem (5 x 10(-8), 5 x 10(-7), 5 x 10(-6) M) caused a dose-dependent reduction in ventricular arrhythmias upon reperfusion following 10 min of regional ischemia. The incidence of reperfusion-induced ventricular fibrillation (RVF) was 50%, 0% (p less than 0.05) and 0% (p less than 0.05) with 5 x 10(-8), 5 x 10(-7), 5 x 10(-6) M diltiazem, respectively, compared with 60% in the control group. Preischemic administration of the 1-isomer caused different dose-dependent reduction in RVF. With 5 x 10(-6) M, the 1-isomer also reduced the incidence of RVF to 0% (p less than 0.05). However below this concentration it was ineffective (67%). D-diltiazem (5 x 10(-7) and 5 x 10(-6) M) increased coronary flow from 11.5 +/- 1.9 ml/min to 15.3 +/- 1.6 ml/min (p less than 0.05) and 15.2 +/- 1.0 ml/min (p less than 0.05) respectively, prior to ischemia. In contrast, the same dose of the 1-isomer did not alter coronary flow. The highest dose (5 x 10(-6) M) of d-diltiazem decreased heart rate by approximately 30% during the reperfusion phase, but all other concentrations had no significant effects.(ABSTRACT TRUNCATED AT 250 WORDS)     

辅酶Q10治疗扩张型心肌病心力衰竭患者的疗效观察

目的观察辅酶Q10扩张型心肌病(DCM)伴慢性心力衰竭(CHF)的疗效和安全性。方法将54例扩张型心肌病伴中、重度心力衰竭患者随机分为两组,对照组27例,常规使用洋地黄、利尿药、血管紧张素转换酶抑制剂、β-受体阻滞剂等药物治疗;治疗组27例,在对照组基础上,加用口服辅酶Q10,10mg,3次/d,疗程为2个月。观察辅酶Q10治疗前及治疗2个月后,对心功能分级、左室射血分数(LVEF)、恶性心律失常等影响。结果治疗组临床心功能分级明显改善、LVEF值显著提高、恶性心律失常发生率明显减少。结论辅酶Q10能明显改善DCM患者的心功能和预后、降低猝死率,临床疗效可靠、安全。     

Influence of noradrenaline and temperature on the isolated perfused rat heart

Myocardial protection during open heart surgery is achieved by general cooling and cold cardioplegia. However sympathetic activation during the operation causes raised circulating catecholamine levels that might negatively influence the myocardial metabolism. Moreover, local liberation of catecholamines, in “poorly perfused” regions of the myocardium in patients with ischemic heart disease, might occur. In respect of these problems, we studied the influence of noradrenaline at different temperatures on the isolated perfused rat heart. The temperatures chosen were: 10, 20, 32, 37 and 39°C. The results show clearcut adverse effect of noradrenaline at 32° and higher, on metabolism and hemodynamic performance. At lower temperatures there still seem to be an adverse effect of noradrenaline although not statistically significant. The results of this study indicates the importance of presurgical myocardial protection especially of badly perfused myocardial areas. Such protection could be accomplished by β-blockade and/or loading of the myocardium with glycogen by glucose-insulin-potassium infusion.     

A protective action of coenzyme Q10 on chlorpromazine-induced cell damage in the cultured rat myocardial cells

The interactions between coenzyme Q10 (CoQ) and chlorpromazine (CPZ) were studied after CPZ-induced injury of cultured myocardial cells of new-born Wistar rats. Administration of 7.5 X 10(-6) M of CPZ caused decreases in adenosine triphosphate (ATP) contents and beating rates by 77.4% and 54.2%, respectively. These changes were dependent on the dosage of CPZ. Histologically, many lamellated granules appeared in the cytoplasm and seemed to originate from mitochondria. The decreased density of the mitochondrial matrix and an irregular arrangement of cristae were also observed. Coincubation of the cultures with CPZ and CoQ led to a dose-dependent increase in ATP contents and beating rates. The appearance of increased number of granules in the cytoplasm was suppressed. Indomethacin, an inhibitor of prostaglandin synthesis, interfered with the effects of CoQ on the CPZ-induced myocardial cell injury. These findings suggest that CoQ may protect myocardial cells from CPZ-induced injury, and that prostaglandins may play an important role in the action of CoQ.     

Studies on cumene hydroperoxide-induced lipid peroxidation in the isolated perfused rat heart

In the isolated, perfused rat heart, lipid peroxidation, induced by cumene hydroperoxide (Cum OOH), is accompanied by the release of malondialdehyde (MDA). Using a modified perfusion technique resulting in the separate collection of coronary and interstitial effluent, it can be shown that upon Cum OOH (0.5 mM) perfusion there is an immediate release of MDA in the coronary effluent and a delayed release in the interstitial fluid, indicating the susceptibility and coronary vascular tissue towards free radical-induced lipid peroxidation. Perfusion with Cum OOH leads to an initial increase of the coronary flow and a depressed contractility followed by a cardiac arrest concomitantly with the onset of MDA release in the interstitial fluid. Finally, during prolonged perfusion the coronary flow diminishes and contracture of the heart muscle ('stone heart') develops. These phenomena resemble those occurring during the 'calcium paradox'. Although the contractility diminishes immediately after the perfusion with Cum OOH the tissue ATP level and energy charge (formula; see text) remain constant. From the moment of cardiac arrest the ATP and creatine phosphate levels gradually decrease and the energy charge drops simultaneously with the appearance of MDA in the interstitial fluid. In contrast to the calcium paradox there is no simultaneous increase in the myocardial AMP level. Various mitochondrial enzymes (cytochrome c oxidase, monoamine oxidase, carnitinepalmitoyltransferase I and palmitoyl CoA synthetase) were tested and not affected by Cum OOH perfusion. During the development of contracture after 20 min of Cum OOH perfusion massive contraction band necrosis of cardiac tissue occurs. However, overall protein release is lower when compared with the protein release during the calcium paradox.(ABSTRACT TRUNCATED AT 250 WORDS)