• Animal cells and systems
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• v.14 no.4
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• pp.245-252
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• 2010

Iron uptake in mitochondria and fractionated mitochondria compartments was studied to understand iron transport in heart mitochondria. The inner membrane is most active in iron uptake. Mitochondrial uptake was dependent on iron concentration and the amount of mitochondria. Iron transport was inversely proportional to pH in the range of 6.0 to 8.0. Iron transport reached a maximum after 30 min of incubation at $37^{\circ}C$. Iron uptake was inhibited by 1 mM ATP and stimulated by 1 mM ADP. The oxidative phosphorylation inhibitor oligomycin inhibited iron uptake, but rotenone and antimycin A did not. The divalent ions $Mg^{2+}$, $Cu^{2+}$, $Mn^{2+}$, and $Zn^{2+}$ suppressed iron uptake at $10\;{\mu}M$ and stimulated it at 1 mM. The divalent ion $Ca^{2+}$ stimulated iron uptake at $10\;{\mu}M$ and suppressed it at 1 mM, competing with iron. The uptake of calcium was stimulated by 10 to $1000\;{\mu}M$ ATP, while iron uptake was stimulated reciprocally by 10 to $1000\;{\mu}M$ ADP, suggesting that these ions have movements similar to those of ATP and ADP.

• Animal cells and systems
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• v.14 no.2
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• pp.91-98
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• 2010

Male rats were given a single injection of iron, and temporal changes in iron content and iron-induced effects were examined in heart cellular fractions. Over a period of 72 h, the contents of total and labile iron, reactive oxygen species, and NO in tissue homogenate, nuclear debris, and postmitochondrial fractions were mostly constant, but in mitochondria they continuously increased. An abrupt decrease in membrane potential and NAD(P)H at 12 h was also found in mitochondria. The respiratory control ratio was reduced slowly with a slight recovery at 72 h, suggesting uncoupling by iron.While the ATP content of tissue homogenate decreased steadily until 72 h, it showed a prominent increase in mitochondria at 12 h. Total iron and calcium concentration also progressively increased in mitochondria over 72 h. Enzyme activity of the oxidative phosphorylation system was significantly altered by iron injection: activities of complexes I, III, and IV were reduced considerably, but complex II activity and the ATPase activity of complex V were enhanced. A reversal of activity in complexes I and II at 12 h suggested reverse electron transfer due to iron overload. These results support the argument that mitochondrial activities including oxidative phosphorylation are modulated by excessive iron.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.355-361
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• 2009

Mitochondria play a key role in maintaining life by producing ATP and heat. Recent researches have demonstrated that degenerative diseases such as heart failure, obesity/diabetes, cardiovascular disease, and psychiatric diseases are accompanied by mitochondria dysfunction. In this sense, mitochondria medicine considers the significance of mitochondria in human pathology and tries to explain degenerative diseases as a fatal consequence of mitochondria dysfunction. Here, I introduce the fundamentals of mitochondria physiology and present examples showing the relationship between mitochondria dysfunction and chronic complex diseases. Although mitochondria medicine uses a molecular biological approach predominantly, a biomedical engineering approach might play a critical role in unveiling the complexity of mitochondria medicine and in its application to the diagnosis and treatment of chronic diseases. Thus, I also briefly review the prospects of research using biomedical engineering methods.

• Applied Microscopy
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• v.24 no.4
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• pp.41-51
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• 1994

The topology of the enzyme has been investigated by biochemical studies including chemical labeling and cross linking. Thirteen subunits(polypeptides) of the cytochrome-c-oxidase have localistic characteristics of existing in the matrix side or cytoplasmic side in the mitochondria. In order to observe the distribution of the enzyme subunit on the mitochondria membrane, immunogold-labeling methods were employed. Antibody was obtained from the serum of immunized rabbit with enzyme subunit antigen which was obtained from cytochrome-c-oxidase of the beef heart muscle mitochondria. Beef heart muscle tissue as a tissue antigen was stained with immunized rabbit IgG and protein A gold complex. Electron microscopy has identified the existance of cytochrome-c-oxidase subunit $Mt_I,\;Mt_{II}\;and\;Mt_{III}$ on the membrane of cristae and outer chamber of mitochondria and the subunit $C_{IV}$ on the membrane of cristae and matrix of mitochondria. Particularly, the subunit $C_{IV}$ was also observed to exist in the sarcoplasm of muscle tissue.

• Applied Microscopy
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• v.23 no.2
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• pp.107-123
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• 1993

The ultrastructural changes of the cardiac ganglion and granule-containing cells in the heart of vacor-induced diabetic Mongolian gerbils were studied by electron microscopy. After one month of vacor-induced diabetes the ganglion cells showed increase in numbers of dense bodies and mitochondria compared with the normal cardiac ganglion. Most of the satellite cells were filled with numerous phagosomes containing digested debris. Both electron-dense and lucent types of degenerating axon terminals were observed. The former was characterized by clusters of agranular vesicles and numerous mitochondria. The electron lucent type of degenerating axon terminal contained a few agranular vesicles and swollen mitochondria. Degenerating unmyelinated and myelinated axons contained large numbers of dense bodies, lamellar bodies, and mitochondria. Numerous macrophages containing phagosomes were reveled in the interstitial spaces. Some of the granule-containing cells in the heart showed a variety of degenerative changes and a decreased number of dense-cored vesicles. After three months of vacor-induced diabetes the unmyelinated and myelinated axons showed degenerative changes, whereas no structure changes could be demonstrated in intraatrial ganglion and granule containing cells. The satellite cells containing engulfed debris were observed in the cardiac ganglion cells. These results suggest that the degenerative changes occur in the cardiac ganglion cells of vacor-induced diabetic Mongolian gerbils as well as atrial granule-containing cells.

• The Korean Journal of Pharmacology
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• v.18 no.2
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• pp.89-102
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• 1982

The $Na^+-and\;K^+-induced\;Ca^{++}$ release was measured isotopically by millipore filter technique in pig heart mitochondria. With EGTA-quenching technique, the characteristics of mitochondrial $Ca^{++}-pool$ and the sources of $Ca^{++}$ released from mitochondria by $Na^+\;or\;K^+$ were analyzed. The mitochondrial $Ca^{++}-pool$ could be distinctly divided into two components: internal and external ones which were represented either by uptake through inner membrane, or by energy independent passive binding to external surface of mitochondria, respectively. In energized mitochondria, a large portion of $Ca^{++}$was transported into internal pool with little external binding, while in de-enerigzed state, a large portion of transported $Ca^{++}$ existed in the external pool with limited amount of $Ca^{++}$ in the internal pool which was possibly transported through the $Ca^{++}-carrier$ present in the inner membrane. $Na^+$ induced the $Ca^{++}$ release from both internal pool and external pool and external binding pool of mitochondria. In contrast, $K^+$ did not affect $Ca^{++}$ of the internal pool, but, displaced $Ca^{++}$ bound to external surface of the mitochondria. When the $Ca^{++}-reuptake$ was blocked by EGTA, the $Ca^{++}$ release from the internal pool by $Na^+$ was rapid; the rate of $Ca^{++}-efflux$ appeared to be a function of $[Na^+]^2$ and about 8mM $Na^+$ was required to elicit half-maximal velocity of $Ca^{++}-efflux$. So it was revealed that $Ca^{++}-efflux$ velocity was particulary sensitive to small changes of the $Na^+$ concentration in physiological range. Energy independent $Ca^{++}-binding$ sites of mitochondrial external surface showed unique characteristics. The total number of external $Ca^{++}-binding$ sites of pig heart mitochondria was 29 nmoles per mg protein and the dissociation constant(Kd) was $34{\mu}M$. The $Ca^{++}-binding$ to the external sites seemed to be competitively inhibited by $Na^+\;and\;K^+$; the inhibition constant(Ki) were 9.7 mM and 7.1 mM respectively. Considering the intracellular ion concentrations and large proportion of $Ca^{++}$ uptake in energized mitochondria, the external $Ca^{++}-binding$ pool of the mitochondria did not seem to play a significant role on the regulation of intracellular free $Ca^{++}$ concentration. From this experiment, it was suggested that a small change of intracellular free $Na^+$ concentration might play a role on regulation of free $Ca^{++}$ concentration in cardiac cell by influencing $Ca^{++}-efflux$ from the internal pool of mitochondria.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.2
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• pp.57-64
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• 2007

Ischemic preconditioning (IPC) is known to protect the heart against ischemia/reperfusion (IR)-induced injuries, and regional differences in the mitochondrial antioxidant state during IR or IPC may promote the death or survival of viable and infarcted cardiac tissues under oxidative stress. To date, however, the interplay between the mitochondrial antioxidant enzyme system and the level of reactive oxygen species (ROS) in the body has not yet been resolved. In the present study, we examined the effects of IR- and IPC-induced oxidative stresses on mitochondrial function in viable and infarcted cardiac tissues. Our results showed that the mitochondria from viable areas in the IR-induced group were swollen and fused, whereas those in the infarcted area were heavily damaged. IPC protected the mitochondria, thus reducing cardiac injury. We also found that the activity of the mitochondrial antioxidant enzyme system, which includes manganese superoxide dismutase (Mn-SOD), was enhanced in the viable areas compared to the infarcted areas in proportion with decreasing levels of ROS and mitochondrial DNA (mtDNA) damage. These changes were also present between the IPC and IR groups. Regional differences in Mn-SOD expression were shown to be related to a reduction in mtDNA damage as well as to the release of mitochondrial cytochrome c (Cyt c). To the best of our knowledge, this might be the first study to explore the regional mitochondrial changes during IPC. The present findings are expected to help elucidate the molecular mechanism involved in IPC and helpful in the development of new clinical strategies against ischemic heart disease.

• BMB Reports
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• v.41 no.2
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• pp.153-157
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• 2008

The objective of the present study was to identify mitochondrial components associated with the damage caused by iron to the rat heart. Decreased cell viability was assessed by increased presence of lactate dehydrogenase (LDH) in serum. To assess the functional integrity of mitochondria, Reactive Oxygen Species (ROS), the Respiratory Control Ratio (RCR), ATP and chelatable iron content were measured in the heart. Chelatable iron increased 15-fold in the mitochondria and ROS increased by 59%. Deterioration of mitochondrial function in the presence of iron was demonstrated by low RCR (46% decrease) and low ATP content (96% decrease). Using two dimensional gel electrophoresis (2DE), we identified alterations in 21 mitochondrial proteins triggered by iron overload. Significantly, expression of the $\alpha$, $\beta$, and d subunits of $F_1F_o$ ATP synthase increased along with the loss of ATP. This suggests that the $F_1F_o$ ATP synthase participates in iron metabolism.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.3
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• pp.209-217
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• 2024

In addition to cellular damage, ischemia-reperfusion (IR) injury induces substantial damage to the mitochondria and endoplasmic reticulum. In this study, we sought to determine whether impaired mitochondrial function owing to IR could be restored by transplanting mitochondria into the heart under ex vivo IR states. Additionally, we aimed to provide preliminary results to inform therapeutic options for ischemic heart disease (IHD). Healthy mitochondria isolated from autologous gluteus maximus muscle were transplanted into the hearts of Sprague-Dawley rats damaged by IR using the Langendorff system, and the heart rate and oxygen consumption capacity of the mitochondria were measured to confirm whether heart function was restored. In addition, relative expression levels were measured to identify the genes related to IR injury. Mitochondrial oxygen consumption capacity was found to be lower in the IR group than in the group that underwent mitochondrial transplantation after IR injury (p < 0.05), and the control group showed a tendency toward increased oxygen consumption capacity compared with the IR group. Among the genes related to fatty acid metabolism, Cpt1b (p < 0.05) and Fads1 (p < 0.01) showed significant expression in the following order: IR group, IR + transplantation group, and control group. These results suggest that mitochondrial transplantation protects the heart from IR damage and may be feasible as a therapeutic option for IHD.

• The Korean Journal of Pharmacology
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• v.14 no.1_2
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• pp.1-11
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• 1978

The $Na^+$-and $K^+$-induced $Ca^{++}$ release was measured isotopically by Milipore filter technique in mitochondria isolated from rabbit ventricles. The release of $Ca^{++}$ from mitochondria could be induced by 1-3 mM of $Na^+$ added in incubating medium under the presence of 0.5mM EGTA to prevent the released $Ca^{++}$ from rebinding with mitochondrial membrane. The amount of $Ca^{++}$ released was increased by increasing the concentration of $Na^+$ added. 100mM $K^+$, in itself, did not induce the $Ca^{++}$ release from cardiac mitochondria, the $Na^+$-induced $Ca^{++}$ release, however, was potentiated by the presence of $K^+$. The potentiation of $Na^+$-induced $Ca^{++}$ release by $K^+$ was proportional to the $Na^+/K^+$ ratio presented in the incubating medium. Among the monovalent cations other than $Na^+$, the release of $Ca^{++}$ from cardiac mitochondria was shared only by $Li^+$. The $Na^+$-induced $Ca^{++}$ release could be also observed in the mitochondria isolated from liver and kidney. However, the $Na^+$ sensitivity was somewhat lower in liver and kidney mitochondria than in heart mitochondria. The release of $Ca^{++}$ induced by $Na^+$ in the mitochondria isolated from the experimentally produced failured heart was not different from that in the normal heart mitochondria, and was not directly modified by $10^{-6}{\sim}10^{-5}$ M of Ouabain. From the experiments, it was suggested that the $Ca^{++}$ released from mitochondria by $Na^+$ could be used in excitation-contraction coupling process to initiate the contraction of the cardiac myofibrils. Futhermore, it appeared that the phenomenon of $Ca^{++}$ release from cardiac mitochondria by $Na^+$ and $K^+$ might be related to the inotropic effect of digitalis glycoside which could bring about the increase of $Na^+$ or the reduction of $K^+$ intracellulary through the inhibition of $Na^+$, $K^+$-ATPase.