• 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.

• Tuberculosis and Respiratory Diseases
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• v.54 no.5
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• pp.532-541
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• 2003

Background : Phospholipase $A_2$ ($PLA_2$) has been known to be involved in the pathogenesis of acute lung injury (ALI) including ARDS. Since doxycycline has the property of inhibiting secretory group II $PLA_2$, the therapeutic effect of doxycycline hyclate was investigated for gut ischemia/reperfusion (I/R)-induced ALI in Sprague-Dawley rats. Methods : ALI was induced in Sprague-Dawley rats by clamping of the superior mesenteric artery for 60 min, followed by 120 min of reperfusion. To confirm the pathogenetic mechanisms of this ALI associated with neutrophilic oxidative stress, we measured bronchoalveolar lavage (BAL) protein content and lung MPO, and performed cyto-chemical electron microscopy for detection of free radicals, assay of $PLA_2$ activity and cytochrome-c reduction assay. Results : In gut I/R-induced ALI rats, protein leakage, pulmonary neutrophil accumulation, free radical production and lung $PLA_2$ activity were all increased. These effects were reversed by doxycycline hyclate. Conclusion : Doxycycline appears to be effective in ameliorating the gut I/R-induced ALI by inhibiting $PLA_2$, thereby decreasing the production of free radicals from neutrophils.

• Journal of Chest Surgery
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• v.35 no.7
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• pp.501-510
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• 2002

Background: The various pathogeneses of acute respiratory distress syndrome have been suggested but not established yet. In the present study, the role of group II phospholipase $A_2$($PLA_2$) in the pathogenesis of gut ischemia-reperfusion(I/R) induced acute lung injury (ALI), especially in the pulmonary oxidative stress with infiltration of neutrophils was investigated. Material and Method: To induce ALI, reperfusion of mesentery was done for 120 min after clamping of superior mesenteric artery for 60 min in Sprague-Dawley rats that weighed about 300g. To exmaine the role of group II $PLA_2$ in ALI, especially endothelial injury associated with the action of neutrophils, lung myeloperoxidase activity, lung leak index, bronchoalveolar lavage fluid protein were measured, and pulmonary $PLA_2$ activity changes in gut I/R were also measured. The role of group II $PLA_2$in the neutrophilic generation of free radicals was assessed by inhibiting group II $PLA_2$ with rutin, manoalide and scalaradial. Furthermore, to verify the oxidative stress in the lung, histologic and free radical detecting cytochemical electron microscopy were done. Result: After reperfusion, ALI was developed with accumulation of neutrophils in the lung, which was confirmed by the increase of myeloperoxidase activity, lung leak index and bronchoalveolar lavage protein (p<0.001). The pulmonary and intestinal group II $PLA_2$ activities significantly increased after gut I/R which were reversed by rutin(p<0.001). In vitro, cytochrome-c reduction assay denoted the inhibitory effects of rutin, scalaradial and manoalide on the production of free radicals from isolated human neutrophils. Histologically, neutrophilic accumulation and pericapillary edema in the lung after gut I/R was detected by light microscopy which was suppressed by rutin. In $CeCl_3$ cytochemical electron microscopy, the increased production of hydrogen peroxide in the lung after gut I/R was confirmed and also the production of hydrogen peroxide was decreased by rutin. Conclusion: On the basis of these experimental results, the inhibition of group II $PLA_2$ seemed to mitigate gut I/R-induced ALI by suppressing the production of free radicals from the infiltrated neutrophils. Collectively, group II $PLA_2$ seems to play a crucial role in gut I/R-induced ALI by neutrophilic oxidative stress.

• Journal of Chest Surgery
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• v.32 no.7
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• pp.637-647
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• 1999

Background: Ischemia-reperfusion injury is one of the major contributing causes of early graft failure in lung transplantation. It has been suggested that triiodothyronine (T3) may ameliorate ischemia-reperfusion injury to various organs in vivo and in vitro. Predicting its beneficial effect for ischemic lung injury, we set out to demonstrate it by administering T3 into the in situ canine ischemia-reperfusion model. Material and Method: Sixteen adult mongrel dogs were randomly allocated into group A and B. T3 $(3.6\mug/kg)$ was administered before the initiation of single lung ischemia in group B, whereas the same amount of saline was administered in group A. Ischemia was induced in the left lung by clamping the left hilum for 100 minutes. After reperfusion, various hemodynamic parameters and blood gases were analyzed for 4 hours while intermittently clamping the right hilum in order to allow observation of the injured left lung function. Result: Arterial oxygen partial pressure $(PaO_2)$ decreased 30 minutes after reperfusion and recovered gradually thereafter in both groups. In group B the decrease of $PaO_2$ was less marked than in group A. The recovery of $PaO_2$ was faster in group B than in group A. The differences between the two groups were statistically significant from 30 minutes after reperfusion $(125\pm34$ mmHg and $252\pm44$ mmHg, p<0.05) until the end of the experiment $(178\pm42$mmHg and $330\pm37$ mmHg, p<0.05). The differences in the arterial carbon dioxide pressure, airway pressure and lung compliance showed no statistical significance. The malondialdehyde (MDA) level, measured from the tissue obtained 240 minutes after reperfusion, was lower in group B $(0.40\pm0.04\mu$M) than in group A $(0.53\pm0.05\mu$M, p<0.05). The ATP level of group B $(0.69\pm0.07\mu$M/g) was significantly higher than that of group A $(0.48\pm0.07\mu$M/g, p<0.05). The microscopic exami nation revealed varying degrees of injury such as perivascular neutrophil infiltration, capillary hemorrhage and interstitial congestion. There were no differences in the microscopic findings between the two groups. CONCLUSION T3 has beneficial effects on the ischemic canine lung injury including preservation of oxygenation capacity, less production of lipid peroxidation products and a higher level of tissue ATP. These results suggest that T3 is effective in pulmonary allograft preservation.

• 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.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.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.335-345
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• 1996

A critical role of oxygen-derived free radicals has been implicated in ischemia/reperfusion (I/R)-induced brain damage. In this study, we have produced experimental I/R to the brains of Mongolian gerbil (Meriones unguiculatus) by a transient occlusion and release of the common carotid arteries. We have attempted to determine whether the oxidative stress is generated upon I/R and whether this oxidative stress is linked to the cell damage. Since hippocampus has been suggested as one of the most vulnerable regions of the brain to the oxidative stress, we analyzed samples from hippocampus in comparison with those from cortex. In addition, we have examined the expression of heat shock protein 70kD species (HSP70) in these regions in order to evaluate a possible role of this protein in I/R-induced brain damage. To determine whether the oxidative stress is produced upon I/R, we measured the glutathione oxidation, GSSG/ (GSH + 2xGSSG), as an index of oxidative stress. We found an increase of the glutathione oxidation primarily in hippocampus upon I/R. To determine whether this oxidative stress is linked to the cell damage, we measured the degree of lipid peroxidation upon I/R. We found an increase of lipid peroxidation in both regions. However, the magnitude of increases was greater in hippocampus than in cortex. In addition, we found that changes in both the magnitude and the temporal patterns of glutathione oxidation closely correlated with those of lipid peroxidation. Our study provides biochemical evidences that the oxidative stress is generated upon I/R and this oxidative stress is linked to the oxidative cell damage. Our study also provides evidences that the degree of oxidative stress as well as oxidative cell damage is greater in hippocampus than in cortex. We could not find difference in the basal level of HSP70 expression between hippocampus and cortex, indicating that the intrinsic vulnerability of hippocampus cannot be explained by the lower level of HSP70 expression. We did find, however, that the induction of HSP70 expression upon I/R was impaired in the hippocampus. This impairment appeared to be at the transcriptional level. These results suggest that the measurement of HSP70 induction may be employed as a useful predictor of differential cellular susceptibilities to the I/R-induced brain damage.

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.31-37
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• 1996

The protective effect of 'ischemic preconditioning (IP)'on ischemia-reperfusion injury of heart has been reported in various animal species, but the mechanism is unclear. In an attempt to elucidate the mechanism of IP, we examined the effects of blockers against adenosine and protein kinase C in preconditioned heart of rat. The hearts perfused with oxygen-saturated Krebs-Henseleit solution by Langendorff method were exposed to 30 min global ischemia followed by 20 min reperfusion. IP was performed with three episodes of 5 min ischcmia and 5 min reperfusion just before ischemia-reperfusion. IP prevented the depression of contractile function and the myocardial contracture in the ischemic-reperfused heart and reduced the release of lactate dehydrogenase during the reperfusion period. Polymyxin B, chelerythrine and colchicine, PKC inhibitors, attenuated almost completely the anti-ischemic effect of IP, while adenosine receptor antagonists did not. These results indicate that PKC may be a crucial intracellular mediator in anti-ischemic action of IP in ischemic-reperfused rat heart, while adenosine may not be involved in the mechanism of IP.

• Journal of Chest Surgery
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• v.34 no.3
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• pp.212-223
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• 2001

배경: 이식폐의 보존 및 재관류 동안 cyclic adenosine monophosphate(cAMP)와 nitric oxide(NO)는 폐혈관 내 순환조절을 유지하는데 있어 중심적인 역할을 한다. 그러나 내치세포내의 cAMP와 NO 모두 허혈-재관류 과정 동안에 현저하게 감소한다. 이에 저자는 low potassium dextran(LPD) 폐조본액에 cAMP의 유사체인 dibutyry1 cAMP(db-cAMP)와 NO의 공여물질인 nitroglycerin(NTG)을 첨가하여 이들의 폐보존 효과를 알아보고, 이들은 첨가한 폐보존액 들의 효과를 비교하였다. 대상 및 방법: 토끼 폐장 분리관류 모형에 실험군은 각각 6마리씩 4개군으로 단순 LPD 페보존액만 사용한 경우(I군), LPD 용액에 NTG 만 참가한 경우(II군), cAMP 만 첨가한 겨우(III군) 그리고 두가지 모두를 첨가한 경우는 IV군으로 분류하였으며, 폐보존액이 주입된 심폐블록은 영상 1$0^{\circ}C$에서 24시간 동안 보관한 다음 100% 산소농도에서 기계호흡을 하면서 신선 정맥혈로 30분 동안 재관류를 시행하였다. 재관류폐의 평가를 위해 폐기능 및 폐부종 정도를 정량 측정하였으며, 유출로 혈액으로부터 tumor necrosis factor $\alpha$(TNF-$\alpha$)와 간접적인 NO의 총량을 알기 위해 nitrite/nitrate의 양을 측정하였다. 또한 재관류가 끝난 후 광학 및 전자현미경학적 소견을 관찰하였다. 결과: 모든 실험군 중 제 IV군 의 폐보존 능력이 가장 우수하였으나, 제 II, III, IV군 사이는 통RP적으로 유의한 차이가 없었다. 제 I군은 제 II, III, IV군들에 비해 유의하게 폐기능이 가장 나쁘고 폐부종 정도가 가장 심했다(p<0.05). 제 II군은 제 III군에 비해 더 좋은 폐기능을 보였고, 폐부종 정도가 덜 하였으나 통계적은 유의성은 없었다. TNF-$\alpha$ 는 제 IV 군이 Irns에 비해 유의하게 분비량이 적었다. (p<0.05). 총 NO의 양은 제 II군과 IV 군이 제 I 군과 III군보다 유의하게 높았으나(p<0.001), 제 II군과 IV군, 제 I군과 III군 사이 비교에서 유의한 차이는 없었다. 또한 제 I 군과 III군에서는 시간이 지남에 따라 유의하게 NO의 양이 점차 감소하였다. (p<0.05). 광학 및 전자현민경 소견상 폐포 및 폐혈관 구조가 제 II, III, IV 군이 I 군에 비해 더 잘 보존되어있었다. 결론: LPD 폐보존액에 db-cAMP 및 NTG의 첨가는 폐보존 효과가 모두 우수함을 확인하였고 이들의 폐보존 효과 차이는 거의 없음을 알수 있었다. 그렇지만 이들의 병합사용이 폐혈관 항상성을 더 잘 유지시킬 수 있고 허혈-재관류 손상을 줄여 폐보존 효과를 높일 수 있을 것이라고 기대된다.

• Journal of Yeungnam Medical Science
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• v.8 no.2
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• pp.1-12
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• 1991