• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.82-82
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• 1993

허혈-재관류손상 심근세포의 DNA에서 8-hydroxydeoxyguanosine (8-OHdG) 생성을 검토하였다. 흰쥐 적출심장의 Langendorff 관류 표본에서 대동맥 차단에 의한 60분 허혈후 산소가 포화된 Kredb-Henseleit용액으로 30분간 재관류 하므로서 허혈-재관류 손상을 유도하였다. 재관류 후 심근세포에서 DNA를 추출하고 HPLC(EC detector)를 이용하여 8-OHdG를 측정하였다. 실험결과 허혈-재관류 심근세포의 DNA에서 8-OHdG 함량이 증가하였으며 이는 $O_2$ 제거물질인 superoxide dismutase와 OH 제거물질인 mannitol에 의하여 방지되었다. Xanthine oxidase외 경쟁적 길항약인 allopurinol도 8-OHdG 생성을 억제하였으며 단백분해효소 억제제인 phenylsulfonylfluoride 그리고 관류액에서 칼슘의 제거 또한 허혈-재관류 심근 DNA의 생성을 방지하였다. 이상의 결과 허혈심근의 재관류시 8-OHdG 생성이 증가하며 이는 재관류 손상과 같은 산화성 심근손상을 평가하는 좋은 Index가 될 수 있을 것으로 여겨진다.

• Journal of Chest Surgery
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• v.29 no.8
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• pp.850-860
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• 1996

Oxygen free radicals and their metabolites have been implicated as possible causes of reperrusion injury In animal models. Their role in the clinical setting is still controversial. The aim of this study was to evaluate the degree of tissue damage, oxidative stress. and changes in the antioxidant enzyme system in patients undergoing cor nary artery bypass graft operations(CABG) with myocardial protection by cold blood cardioplegia. In patients undergoing CABG(n:10). the levels of lactate dehydrogenate(LDH), creatine phosphokinase MB fraction(CK-MB), and malondialdehyde(M DA) were measured In the coronary sinus effluent before aortic cross clamping and 20 minutes after reperfusion. At the same time, the myocardial tissue activities of superoxide dismutase(SOD). catalase(CAT), glutathione peroxiddse(GSHPX), glutathione reductase (GSSGRd), and glucose 6-phosphate dehydrogenate(GfPDH ) were determined in the right atrial auricle excised before aortic cross clamping and in the left atrial auricle excised 20 minutes after reperfuslon. The levels of increased significantly after reperrusion(p< U.05). There were no significant changes in CAT and CfPDH levels. Western blot analysis was performed to study the induction of antioxidant enzyme and demonstrated increased amount of Cu,Zn-SOD.

• Journal of Chest Surgery
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• v.31 no.8
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• pp.739-748
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• 1998

Background: It has been well documented that transient occlusion of the coronary artery causes myocardial ischemia and finally cell death when ischemia is sustained for more than 20 minutes. Extensive studies have revealed that ischemic myocardium cannot recover without reperfusion by adequate restoration of blood flow, however, reperfusion can cause long-lasting cardiac dysfunction and aggravation of structural damage. The author therefore attempted to examine the effect of postischemic reperfusion on myocardial ultrastructure and to determine the rationales for recanalization therapy to salvage ischemic myocardium. Materials and methods: Young Holstein-Friesian cows(130∼140 Kg body weight; n=40) of both sexes, maintained with nutritionally balanced diet and under constant conditions, were used. The left anterior descending coronary artery(LAD) was occluded by ligation with 4-0 silk snare for 20 minutes and recanalized by release of the ligation under continuous intravenous drip anesthesia with sodium pentobarbital(0.15 mg/Kg/min). Drill biopsies of the risk area (antero-lateral wall) were performed at just on reperfusion(5 minutes), 1-, 2-, 3-, 6-, 12-hours after recanalization, and at 1-hour assist(only with mechanical respiration and fluid replacement) after 12-hour recanalization. The materials were subdivided into subepicardial and subendocardial tissues. Tissue samples were examined with a transmission electron microscope (Philips EM 300) at the accelerating voltage of 60 KeV. Results: After a 20-minute ligation of the LAD, myocytes showed slight to moderate degree of ultrastructural changes including subsarcolemmal bleb formation, loss of nuclear matrix, clumping of chromatin and margination, mitochondrial destruction, and contracture of sarcomeres. However, microvascular structures were relatively well preserved. After 1-hour reperfusion, nuclear and mitochondrial matrices reappeared and intravascular plugging by polymorphonuclear leukocytes or platelets was observed. However, nucleoli and intramitochondrial granules reappeared within 3 hours of reperfusion and a large number of myocytes were recovered progressively within 6 hours of reperfusion. Recovery was apparent in the subepicardial myocytes and there were no distinct changes in the ultrastructure except narrowed lumen of the microvessels in the later period of reperfusion. Conclusions: It is likely that the ischemic myocardium could not be salvaged without adequate restoration of coronary flow and that the microvasculature is more resistant to reversible period of ischemia than subendocardium and subepicardium. Therefore, thrombolysis and/or angioplasty may be a rational method of therapy for coronarogenic myocardial ischemia. However, it may take a relatively longer period of time to recover from ischemic insult and reperfusion injury should be considered.

• Journal of Chest Surgery
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• v.34 no.3
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• pp.203-211
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• 2001

배경: AT$_1$수용체의 길항제가 세포 수준에서 심근을 재관류 손사으로부터 보호할수 있다는 것으로 알려져 있지만, 생체내에서의 효과나 그 기전은 아직 명확히 밝혀지지 않았다. 본 연구에서는 백서 심근 허혈 모델을 이용하여, AT$_1$ 수용체의 길항제들 중 하나인 irbesartan이 심근이 재관휴 손상에 미치는 효과를 알아보고, 재관류 손상을 매개하는 한 각지 기전으로서 세포자멸의 기여에 대하여 연구하고자 하였다. 대상 및 방법: Sprague-Dawley 백서에서 무작용 부형약(10% gum arabic: 1군, 개체수=14관) irbesartan(50mg/kg/day :II 군, 개체수=12)을 각각 3일 동안 24시간마다 경구로 투여하였다. 실험동물의 좌 관상 동맥을 45분간 결찰하였다가, 그 후 2시간 동안 재관류시킨 다음 심장을 적출 하였다. TTC(triphenyltetrazolium chloride) 염색법을 이용하여, 허혈 노출 부위에 대한 심근 경색 부위의 비율을 측정하였다. Agarose gel 전기영동상의 DNa 분절 양상과 TUNEL(TdT-mediated dUCP nick end labeling) 염색을 관찰하여 세포자멸이 일어난 정도를 평가하였다. 세포자멸을 조절하는데 관여하는 것으로 알려진 Bcl-2(B-cell lymphoma 2 gene), Bad 등의 단백과 ERK (extracellular signal-regulated kinase), p-38 등 신호전달체계에 작용하는 MAPKs(mitogen-activated protein kinases)의 발현을 측정하기 위하여 Western blot을 시행하였다. 결과: 허혈 노출부위에 대한 심근 경색부위의 비율은 II군(42$\pm$2.7%)이 I군( 64.1$\pm$4.65)에 비해 유의하게 작았다.(p< 0.05), Agarose gel 전기영동상의 DNA laddering 양상은 I군에서 보다 높게 발현되었다. Bad와 ERK2의 발현은 두 군간에 유의한 차이가 없었다. 결론: AT$_1$수용체 길항제인 irbesartan은 생체에서 심근의 재관류 손상을 줄이는 효과가 있었다. 이 효과는 적어도 부분적으로 나만 심근세포의 세포자멸이 감소한 것에 기인한 것으로 설명할 수 있으며, 이 항-세포 자멸 효과는 Bcl-2의 발현증가와 관련이 있는 것으로 추정되었다.

• Journal of Chest Surgery
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• v.31 no.6
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• pp.567-575
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• 1998

Panax Ginseng C.A. Meyer has been known for hundreds of years as the most valuable drug having mysterious effects among all the herbal medicines and plants in Korea. Also, many experimental studies have been performed recently that the various effects were identified and applied clinically. So we attempted an experimental study on the effect of ginsenoside Rg1 mixtures in an isolated rat heart with the use of the Langendorff model. The objective of this study was to determine whether this ginsenoside Rg1 mixtures would protect the myocardial injury after ischemic arrest and reperfusion. Isolated rat hearts were allowed to equilibrate for 20 minutes and were then subjected to 15 minutes of normothermic ischemia. After this ischemic period, isolated rat hearts were allowed to reperfusion for 10 minutes(Ischemic Group). In other group , isolated rat hearts were perfused for 60 minutes continuously with normothermia( Normothermic Group). Hemodynamic and biochemical parameters such as heart rate, left ventricular pressure, +dp/dt max, coronary blood flow and cardiac enzymes were measured during initial perfusion, ischemia, reperfusion period (Ischemic group) and 20, 40 and 60 minutes after continuous perfusion(Normothermic group). After completion of the experiment, this data was evaluated and the following results were obtained. 1. Heart rates showed an increase in both ischemic and normothermic experimental groups, but statistically significant differences were not identified. 2. LVP(Left Ventricular Pressure) showed statistically significant differences in both ischemic and normothermic experimental groups(p<0.005, p<0.01). 3. +dp/dt max showed statistically significant differences in both ischemic and normothermic experimental groups(p<0.01, p<0.01). 4. There were no statistically significant differences in coronary blood flow and cardiac cenzymes in all groups, but experimental groups seemed to have better protection and recovery. These results suggest that ginsenoside Rg1 mixtures has a protective effect on the myocardial injury after ischemia and reperfusion.

• Applied Microscopy
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• v.19 no.1
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• pp.1-18
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• 1989

It has been debated whether postischemic reperfusion is necessarily beneficial to salvage the myocardium after ischemic insult or not. Therefore, this study was undertaken to compare the ultrastructural changes as well as the distribution of $Ca^{2+}$ in the ventricular myocardial cells after transient ischemia and after postischemic reperfusion, and to suspect to what extent the postischemic reperfusion is beneficial. After 10 minutes of ischemia, the heart developed wide I bands, glycogen depletion, intramyofibrillar edema, mitochondrial swelling, clumping and migration of chromatin, ghosts of lipid droplets, disintegration of cell junctions, sarcolemmal disruption, and loss of $Ca^{2+}$ binding capacity of the sarcolemma and the mitochondria. In spite of reperfusion, in a large number of cells, the ultrastructure was more severely damaged, however, $Ca^{2+}$ binding capacity of the sarcolemma and the mitochondria restored. These results suggest that postischemic reperfusion may help the myocardial cells to restore their function to control $Ca^{2+}$ to a certain extent, but that it could aggravate the ischemic insult.

• The Korean Journal of Pharmacology
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• v.28 no.2
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• pp.163-170
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• 1992

The present study was attempted to investigate the effect of cyclobuxine (a steroidal alkaloid) on generation of reactive oxygen metablite and myocardial damage promoted by an exogenous administeration of arachidonate in ischemic-reperfused hearts. Langendorff preparation of the isolated rat heart was made ischemic condition by reducing the flow rate to 0.5 ml/min for 45 min, and then followed by normal reperfusion (7 ml/min) for 5 min. The generation of superoxide anion was estimated by measuring the SOD-inhibitable ferricytochrome C reduction. The degree of lipid peroxidation in myocardial tissue was estimated from the tissue malondialdehyde (MDA) concentration using thiobarbituric acid method. The myocardial cell damage was observed by measuring LDH released into the coronary effluent. Sodium arachidonate $(0.1\;and\;1.0\;{\mu}g/ml)$ infused during the period of oxygenated reperfusion stimulated superoxide anion production dose-dependently. The rate of arachidonate-induced superoxide anion generation was markedly inhibited by cyclobuxine $(1.0\;and\;10\;{\mu}g/ml)$. The production of malondialdehyde was increased by infusion of arachidonate. This increase was prevented by superoxide dismutase (300 U/ml) and cyclobuxine $(1.0\;and\;10\;{\mu}g/ml)$. The release of LDH was increased by sodium arachidonate was also inhibited by superoxide dismutase and cyclobuxine. In conclusion, the present results suggest that cyclobuxine inhibits the production of reactive oxygen metabolite and myocardial damages which were promoted by an administeration of arachidonate during reperfusion of ischemic hearts.

• The Korean Journal of Pharmacology
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• v.30 no.3
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• pp.321-330
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• 1994

The protective effect of 'ischemic preconditioning (PC)' on ischemia-reperfusion injury of heart has been reported in various animal species, but without known mechanisms in detail. In an attempt to investigate the cardioprotective mechanism of PC, we examined the effects of PC on the myocardial oxidative injuries and the oxygen free radical production in the ischemia-reperfusion model of isolated Langendorff preparations of rat hearts. PC was performed with three episodes of 5 min ischemia and 5 min reperfusion before the induction of prolonged ischemia (30 min)-reperfusion(20 min). PC prevented the depression of cardiac function (left ventricular pressure x heart rate) observed in the ischemic-reperfused heart, and reduced the release of lactate dehydrogenase during the reperfusion period. On electron microscopic pictures, myocardial ultrastructures were relatively well preserved in PC hearts as compared with non-PC ischemic-reperfused hearts. In PC hearts, lipid peroxidation of myocardial tissue as estimated from malondialdehyde production was markedly reduced. PC did not affect the activity of xanthine oxidase which is a major source of oxygen radicals in the ischemic rat hearts, but the myocardial content of hypoxanthine (a substrate for xanthine oxidase) was much lower in PC hearts. It is suggested from these results that PC brings about significant myocardial protection in ischemic-reperfused heart and this effect may be related to the suppression of oxygen free radical reactions.

• Proceedings of the KTCVS Conference
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• 1995.10a
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• pp.1-1
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• 1995

• Journal of Chest Surgery
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• v.29 no.8
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• pp.807-815
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• 1996

The protective effect of'ischemic preconditioning'on ischemid-reperfusion injury of heart has been reported in various animal species. but without known mechAnism in detail, In An attempt to investigate the cardioprotective mechanism of ischemic preconditioning, we examined the effects of nitric oxide(UO) synthesis in preconditioned heart of rat The isolated hearts perfused by Langendorfr's method were ex- posed to 30min global ischemia followed by 30min reperfusion with oxygenated Krebs-Henseleit(K-H) sol- ution. Ischemic preconditioning was performed with three episodes of Sm n ischemia and Smin repeyfusion before the induction of prolong ischemia(30min)-reperfusion(30min). Ischemic preconditioning prevented the depression of cardiac function(left ventricular pressure .K heart rate) observed in the ischemia- reperfusion hearts and reduced the release of lactate dehydrogenase during the reperfusion period. On electromicroscopic pictures, myocardial ultrastructures wore relatively well preserved in isthemic preconditioned hearts. N6_nitro-L-arginine methyl ester(L-NAME) an inhibitor of L-arginine citric oxide pathway, was infused at a rate O.Smllmin In a dose of 10mg kg-1 before the initial ischemic preconditioning. neither the protection of cardiac function nor the reduction of LDH releAse in ischemic preconditioning hearts was altered in the presence of added L-NAME On ultrastructural finding, the preservation of morphology in ischemic preconditioning heart was not change by the pretreatment of L-UAME. The failure of the WO synthesis inhibitor to reduce t e effect of ischemic preconditioning may be related to be species specific in that NO may allot be the trigger for ischemic preconditioning in rats.