• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.753-761
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• 1998

Preconditioning of a heart with small doses of catecholamines induces a tolerance against the subsequent lethal ischemia. The present study was performed to find a specific receptor pathway involved with the catecholamine preconditioning and to test if adenosine plays a role in this cardioprotective effect. Isolated rat hearts, pretreated with small doses of ${\alpha}-\;or\;{\beta}-adrenergic$ agonists/antagonists, were subjected to 20 minutes ischemia and 20 minutes reperfusion by Langendorff perfusion method. Cardiac mechanical functions, lactate dehydrogenase and adenosine release from the hearts were measured before and after the drug treatments and ischemia. In another series of experiments, adenosine $A_1\;or\;A_2$ receptor blockers were treated prior to administration of adrenergic agonists. Pretreatments of a ${\beta}-agonist,\;isoproterenol(10^{-9}{\sim}10^{-7}\;M)$ markedly improved the post-ischemic mechanical function and reduced the lactate dehydrogenase release. Similar cardioprotective effect was observed with an ?-agonist, phenylephrine pretreatment, but much higher $concentration(10^{-4}\;M)$ was needed to achieve the same degree of cardioprotection. The cardioprotective effects of isoproterenol and phenylephrine pretreatments were blocked by a ${\beta}_1-adrenergic$ receptor antagonist, atenolol, but not by an ${\alpha}_1-antagonist,$ prazosin. Adenosine release from the heart was increased by isoproterenol, and the increase was also blocked by atenolol, but not by prazosin. A selective $A_1-adenosine$ receptor antagonist, 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX) blocked the cardioprotection by isoproterenol pretreatment. These results suggest that catecholamine pretreatment protects rat myocardium against ischemia and reperfusion injury by mediation of ${\beta}_1-adrenergic$ receptor pathway, and that adenosine is involved in this cardioprotective effect.

• Molecules and Cells
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• v.40 no.8
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• pp.542-549
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• 2017

Cardiomyocyte apoptosis is initiated by various cellular insults and accumulated cardiomyocyte apoptosis leads to the pathogenesis of heart failure. Excessive reactive oxygen species (ROS) provoke apoptotic cascades. Manganese superoxide dismutase (MnSOD) is an important antioxidant enzyme that converts cellular ROS into harmless products. In this study, we demonstrate that MnSOD is down-regulated upon hydrogen peroxide treatment or ischemia/reperfusion (I/R) injury. Enhanced expression of MnSOD attenuates cardiomyocyte apoptosis and myocardial infarction induced by I/R injury. Further, we show that miR-23a directly regulates the expression of MnSOD. miR-23a regulates cardiomyocyte apoptosis by suppressing the expression of MnSOD. Our study reveals a novel model regulating cardiomyocyte apoptosis which is composed of miR-23a and MnSOD. Our study provides a new method to tackling apoptosis related cardiac diseases.

• Applied Microscopy
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• v.22 no.1
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• pp.42-54
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• 1992

To understand the structural changes of the myocardial myocytes and endothelial cells in ischemic and reperfused heart, and to elucidate their roles in those conditions, the authors observed cat and rat myocardium ultrastructurally and evaluated them with morphometric techniques. In cat, mild ischemia and moderate degree reperfusion injury was induced by ligation of the anterior interventricular branch of left coronary artery and reperfusion. In rat, severe ischemia and irreversible reperfusion iniury was made using in vitro Langendorff techniques. In normal cat myocytes, the volume densities of cytoplasm, myofibrils, mitochondria, sarcoplasmic reticulum and T tubules were $0.11{\pm}0.013,\;0.51{\pm}0.096,\;0.25{\pm}0.082,\;0.09{\pm}0.008,\;0.02{\pm}0.010$ (Mean${\pm}$S.D.) respectively, and the myofibril/mitochondria ratio was $2.33{\pm}1.379$. The numerical density and average volume of mitochondria were $0.76{\pm}0.210/{\mu}m^3$ and $0.33{\pm}0.057{\mu}m^3$ respectively. In normal cat endothelial cells, the volume densities of cytoplasm, cytoplasmic vesicles, tubular systems (including endoplasmic reticulum and Golgi apparatus) and mitochondria were $0.43{\pm}0.023,\;0.28{\pm}0.007,\;0.22{\pm}0.021,\;0.03{\pm}0.014$ respectively. The mean thickness of endothelial cells was $230{\pm}45.2{\mu}m$. The numerical density and average volume of cytoplasmic vesicles were $508{\pm}55.0/{\mu}m^3,\;578{\pm}104.8nm^3$ respectively. In cat myocytes which received mild ischemic injury, the volume densities of organelles were not changed significantly in ischemic and reperfusion states. In reperfusion group myocytes, the numerical density of mitochondria was decreased significantly and the average volume was increased significantly. In endothelial cells, the volume density of tubular system in ischemic group and the average volume of cytoplasmic vesicles in reperfusion group were increased significantly. In rat myocytes which received severe ischemic injury, the volume density and average volume of mitochondria were increased significantly, and the volume density of sarcoplasmic reticulum and numerical density of mitochondria were decreased significantly in both ischemic and reperfusion groups. In ischemic and reperfused endothelial cells, the volume density and numerical density of cytoplasmic vesicles, the volume density of cytoplasm were decreased significantly. The volume densities of tubular system were increased significantly in both ischemic and reperfused groups. The volume density of mitochondria in ischemic group and the average volume of cytoplasmic vesicles in reperfusion group showed significant increase. The authors, based on the above observations, conclude that the mitochondria of myocytes and the cytoplasmic vesicles of endothelia are the first group of targets in ischemic and reperfusion injury and in this respect, the degree of ischemic insult is not significant. The role of myocyte mitochondria in reperfusion injury may be insignificant, but endothelial cells may contribute actively to reperfusion injury.

• Journal of Chest Surgery
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• v.31 no.9
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• pp.845-854
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• 1998

Background: S-2-(3 aminoprophlamino) ethylphosphorothioic acid(WR-2721) is one of the radical scavenging thiols. We tested its protective effects in the reperfused heart. Material and Method: The experimental setup was the constant pressure Langendorffs perfusion system. We investigated the radical scavenging properties of this compound in isolated rat hearts which were exposed to 20 minutes ischemia and 20 minutes reperfusion. Four experimental groups were used:group I, control, Amifostine 50 mg(1 mL) peritoneal injection 30 minutes before ischemia(group II), Amifostine 10 mg(0.2 mL) injection during ischemia through coronary artery(group III),and Amifostine 50 mg(1 mL) peritoneal injection 2 hrs before ischemia(group IV). The experimental parameters were the levels of latate, CK-MB, and adenosine deaminase(ADA) in frozen myocardium, the quantity of coronary flow,and left ventricular developed pressure, and it's dp/dt. Statistical analysis was performed using repeated measured analysis of variance and student t-test. Result: The coronary flow of group II and IV were less than group I and III at equilibrium state but recovery of coronary flow at reperfusion state of group II, III, and IV were more increased compared with group I. The change of systolic left ventricular devoloping pressure of group II and IV were less than control group at equilibrium state, which seemed to be the influence of the pharmacological hypotensive effect of amifostine. But it was higher compared with group I at reperfusion state. The lactic acid contents of group II were less than control group in frozen myocardium.(Group I was 0.20 0.29 mM/g vs Group II, which was 0.10 0.11 mM/g). The quantity of CK-MB in myocardial tissue was highest in group IV (P=0.026 I: 120.0 97.8 U/L vs IV: 242.2 79.15 U/L). The adenosine deaminase contents in the coronary flow and frozen myocardium were not significantly different among each group. Conclusion: Amifostine seemed to have significant cardioprotective effect during ischemia and reperfusion injuries of myocardium.

• Journal of Chest Surgery
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• v.33 no.3
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• pp.213-220
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• 2000

Background: Adhesion of leukocytes to myocardium or vascular endothelium has been known as an importation initial step in the ischemia-reperfusion injury which may affect the cardiac function. Therefore, leukocyte-depleted reperfusion may inhibit ischemia-reperfusion induced functional and ultrastructural deterioration. In this study, we quantified the time-dependent expression of the vascular cell adhesion molecule-1(VCMA-1) on piglet myocardium and demonstrated its relation to functional recovery using isolated piglet heart perfusion model. Material and Method: Neonatal(1 to 3 day old) piglet heart was harvested with 4$^{\circ}C$ University of Wisconsin solution (UWS) and presrved in the same solution for 12 hours. Ex vivo model of an isolated working neonatal piglet heart perfusion consisting of membrane oxygenator and roller-pump was used (Fig. 1). Hearts were grouped into leukocyte-non-depleted (group A, n=8) and leukocyte-depleted group(group B, n=8). In group B, hearts were reperfused with leukocyte-depleted blood using a leukocyte filter (Sepacell R, Asahi Medical, Japan). Segments of right atrium were taken before and after 1, 2, 3, and 4 hours of reperfusion for the evaluation of expression of VCAM-1. The intensity of immunohistochyemical satining of the VCAM-1 on the myocardium were graded semiquantitatively (0 to 4). For the evaluation of myocardial stroke work indices were calculated as well at the same time-points. Result: Mean expressins of VCAM-1 on the myocardium at 0, 1, 2, 3, adn 4 hours of reperfusion were 0.63, 1.44, 1.64, 2.65, and 3.34 in group A, while 0.56, 1.40, 1.50, 1.88 and 2.14 in group B (Fig. 3). Mean stroke work indices at 0.5, 1, 2, 3, and 4 hours after reperfusion were 1.35$\times$104, 1.32$\times$104, 1.14$\times$104, 0.81$\times$104, 0.68$\times$104 erg/gm in group A, while 1.40$\times$104, 1.43$\times$104, 1.43$\times$104, 1.28$\times$104, and 1.12$\times$104 erg/em in group B(Fig. 4). Conclusion : In this study, we demonstrated that leukocyte-depletion attenuated the expression of VCAM-1 during reperfusion and the time-dependent functional deterioration of the myocardium was well correlated with the degree of VCAM-1 expression.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.47-52
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• 1999

Blood flow restoration to ischemic zone of the heart is essential to salvage of ischemic tissue. However, there is a large body of evidence documenting that the reperfusion can induce reperfusion injury like reperfusion-induced malignant arrhythmias. In the present study, employing a cat model of regional cardiac ischemia, we examined if reperfusion rendered in a gradual fashion could lower the incidence of reperfusion-induced ventricular fibrillation (VF), which usually precipitated within a few to several tens of seconds after abrupt reperfusion. The experiments were conducted with male mongrel cats (n=46, 2.5-5 kg). The animals in the control and 30 MIN groups were subjected to an episode of 20- and 30-min left anterior descending coronary artery occlusion, respectively, followed by abrupt reperfusion. The animals in 5 G and 10 G groups received gradual reperfusion over a 5- and 10-min period, respectively, following a 20-min occlusion. The proportion of animals that exhibited VF during the reperfusion phase was 11/15 in the control, 7/10 in the 30 MIN, 5/10 in the 5 G and 2/11 in the 10 G groups. The incidence of VF in the 10 G group was significantly lower than that in the control or 30 MIN group subjected to abrupt reperfusion. These results suggest that the gradual reperfusion is a useful procedure against reperfusion-induced VF.

• YAKHAK HOEJI
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• v.44 no.6
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• pp.558-565
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• 2000

SK-1080 is one of the newly developed orally active nonpeptide angiotensinII $AT_1-receptor$ antagonist that selectively acts at $AT_1$ receptor with high affinity. The cardiac effect on ischemia/reperfusion injury of SK-1080 was compared with those of losartan, a prototype of this class, in isolated rat hearts. Isolated perfused rat heart was pretreated with drug for 10 min and then subjected to global ischemia for 30 min followed by reperfusion with- or without drug for 30 min. The possible additive effect of SK-1080 on the platelet aggregation and coagulation in human blood was also studied. We investigated whether SK-1080 effects the platelet aggregation induced by ADP, a platelet agonist partially dependent on $thromboxaneA_2$. The clotting times in the prothrombin time (PT) and activated partial thromboplastin time (APTT) were also examined in human plasma in vitro as coagulation screening test. SK-1080 improved reperfusion function (LVDP, left ventricular developed pressure; PRP, rate-pressure product) in a dose-dependent manner. SK-1080 reduced ADP-induced platelet aggregation compared with vehicle but less than losartan, and did not affect clotting times.

• 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.

• The Korean Journal of Pharmacology
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• v.26 no.1
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• pp.7-12
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• 1990

Cyclobuxine D is a steroidal alkaloid, which was extracted from Buxus microphylla var. koreana Nakai. In our previous studies, we clarified several pharmacological actions of cyclobuxine D: an antiinflammatory action, hypotensive and bradycardiac effects, negative inotropic effects on the several smooth muscles and cardiac muscle. The present study was undertaken to elucidate possible mechanisms by protection of myocardial tells from ischemia and reperfusion induced derangement in cardiac function and metabolism by cyclobuxine D. For this purpose, the isolated rat heart was used. Rat hearts were perfused for 60 min under ischemia conditions in the presence and absence of cyclobuxine D and verapamil, and for 30 min under reperfusion conditions. Ischemia produced a marked decline in contractile force, an increase of resting tension, an immediate release of ATP metabolites and an accumulation of calcium in the left ventricle. Cyclobuxine D (100ng/ml) ameliorated the myocardial injury produced by ischemia.

• Journal of Chest Surgery
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• v.23 no.1
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• pp.1-8
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• 1990

This experiment was carried out under the postulation that activation of an intracellular calcium-calmodulin complex may play an important role in myocardial injury induced by ischemia and reperfusion. Trifluoperazine[TFP], a calmodulin antagonist, was added to the potassium cardioplegic solution and used just before ischemia, and its protective effect from ischemic injury was investigated, using Langendorff rat heart model. TFP group had better post-ischemic functional recovery and lower post-ischemic contracture after 30 minutes of normothermic ischemia. Creatine kinase leakage was also decreased in TFP group but there was no statistical difference between control group and TFP group. We concluded that TFP has some protective effect from myocardial ischemic injury and its effect might be due to prevention of activation of intracellular calcium-calmodulin complex.