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1.
Cryo Letters ; 29(1): 35-42, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18392288

RESUMEN

The involvement of transamination in the respiration of liver mitochondria in ground squirrels during hibernation and arousal has been studied. It was shown by HPLC that, in the presence of glutamate and malate, the formation of alpha-ketoglutarate (KGL), a transamination marker, and fumarate, a product of succinate oxidation, takes place. During arousal, the formation of KGL increased fourfold, and the respiration sensitive to the inhibitor of aspartate transaminase aminooxyacetate (AOA) increased threefold. The function of transamination upon arousal is related to the elimination of oxaloacetate, an endogenous inhibitor of succinate dehydrogenase. In addition, being more resistant to oxidative stress than oxidation, transamination is probably involved in the antioxidant defense required during the rapid rise of body temperature upon arousal. Our experiments showed an increase in the concentration of malonic dialdehyde (MDA), an end product of lipid peroxidation, in liver mitochondria in this state, which can reduce the activity of the enzymes of the tricarboxylic acids cycle. Under these conditions, the transamination contributes to the maintenance of a high respiration rate necessary for arousal.


Asunto(s)
Nivel de Alerta , Hibernación , Mitocondrias Hepáticas/metabolismo , Transaminasas/metabolismo , Aminación , Animales , Cromatografía Líquida de Alta Presión , Glutamatos/metabolismo , Malondialdehído/metabolismo , Estrés Oxidativo , Sciuridae
4.
Tsitologiia ; 45(7): 628-34, 2003.
Artículo en Ruso | MEDLINE | ID: mdl-14989156

RESUMEN

Data on a unique phenomenon of annual involution and neogenesis of thymus gland in hibernating animals are reviewed. In accordance with morphological findings, the annual thymus involution in hibernating animals is close to the age-dependent thymus involution occurring in all mammals once in a lifetime. In opposite, thymus involution in hibernating animals is totally different from the accidental involution. During hibernation, the thymus tissue is substituted by the brown fat tissue. In the spring, thymus gland neogenesis stats with intensive growth of epithelial tissue followed by lymphocyte infiltration and exhaustion of brown tissue. Morphological changes in the thymus gland within the annual cycle were compared with seasonal dynamics of structural and functional changes in peripheral lymphoid organs (spleen, lymphoglandular, peritoneal fluid). A general regularity was observed involving a decreased functional activity of immune cells in autumn, its sharp depression during winter hibernation, and obvious increase in summer with the onset of a season of animal activity. It is supposed that a sharp increase in the tumor necrosis factor (TNF) production observed during short-term awakenings in winter may serve an important link in this unique immune adaptation mechanism. The season changes in cellular TNF secretion suggest a mobilization of protective resources in hibernating animals in autumn and winter, i.e. in seasons when the thymus gland activity is depressed. The annual involution of thymus gland cannot be related to droppings in the environmental or body temperatures, as it comes long before their fall. Additionally, it is not related to ageing, as it occurs already in young hibernating animals. The role of hormones, including melatonine and corticosteroids, in mechanisms regulating thymus gland involution in hibernating animals is discussed.


Asunto(s)
Geriatría , Hibernación/fisiología , Células Madre/fisiología , Timo/fisiología , Adaptación Fisiológica , Animales , División Celular/fisiología , Timo/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo
5.
Biofizika ; 44(6): 1059-62, 1999.
Artículo en Ruso | MEDLINE | ID: mdl-10707280

RESUMEN

The effect of mitochondria on the redox reaction between oxymyoglobin (oxy-Mb) and ferricytochrome c was studied. The parameters of this reaction in the absence of mitochondria have been investigated earlier. It is shown that the course of oxidation of oxymyoglobin by cytochrome c in the presence of mitochondria differs from that without mitochondria: no reduced cytochrome c is observed; in addition, the order of this redox reaction and its dependence on pH and ionic strength change. The factors influencing the state of mitochondrial membrane and uncouples enhance markedly the reaction rate. The conclusion was drawn that mitochondria directly participate in the oxymyoglobin-cytochrome c redox reaction. The possibility of this reaction in vivo under extreme conditions and during pathological processes is discussed.


Asunto(s)
Grupo Citocromo c/metabolismo , Mitocondrias Hepáticas/metabolismo , Oxihemoglobinas/metabolismo , 2,4-Dinitrofenol/farmacología , Animales , Carbonil Cianuro p-Trifluorometoxifenil Hidrazona/farmacología , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Oxidación-Reducción , Ratas , Desacopladores/farmacología
6.
Biochemistry (Mosc) ; 62(12): 1429-34, 1997 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9481876

RESUMEN

Addition of 0.5-5 microM cytochrome c and 30 microM lauric acid to rat liver mitochondria stimulated the respiration rate. Stimulation of respiration by cytochrome c was prevented by cyclosporin A and was not observed in the absence of lauric acid. High amplitude swelling of mitochondria in the presence of lauric acid was also potentiated by cytochrome c; this effect was prevented by cyclosporin A or by EGTA. Polylysine (0.35 microM) induced cyclosporin A-insensitive high amplitude swelling of mitochondria. Polylysine-induced swelling was stimulated by lauric acid and cytochrome c; the effect was prevented by cyclosporin A. Incubation of mitochondria with 30 microM lauric acid resulted in an increase in cytochrome c concentration in the incubation medium. Added cytochrome c is supposed to potentiate the laurate-induced cyclosporin A-sensitive permeability transition in cytochrome c-depleted mitochondria.


Asunto(s)
Ciclosporina/farmacología , Grupo Citocromo c/metabolismo , Ácidos Grasos/metabolismo , Mitocondrias Hepáticas/efectos de los fármacos , Animales , Membranas Intracelulares/efectos de los fármacos , Membranas Intracelulares/metabolismo , Mitocondrias Hepáticas/metabolismo , Dilatación Mitocondrial/efectos de los fármacos , Oxígeno/metabolismo , Permeabilidad/efectos de los fármacos , Ratas
7.
Biofizika ; 42(6): 1297-300, 1997.
Artículo en Ruso | MEDLINE | ID: mdl-9490118

RESUMEN

During the deep hibernation (at 5-6 degrees C of the heart temperature) and during arousal from hibernation (at 15-16 degrees C) insulin have no effect on contractility. Two opposite inotropic effects of insulin at concentrations 0.1-50 nM were found at higher temperature of arousing: a transient positive inotropic effect between 21-28 degrees C, and a negative one (about 20-30% from the control value) above 28 degrees C. In active summer and winter animals insulin produced mainly the negative inotropic effect.


Asunto(s)
Nivel de Alerta/fisiología , Hibernación/fisiología , Hipoglucemiantes/farmacología , Insulina/farmacología , Contracción Miocárdica/efectos de los fármacos , Sciuridae/fisiología , Animales , Insulina/fisiología
8.
Biochem Mol Biol Int ; 38(5): 863-70, 1996 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9132155

RESUMEN

Oxygen consumption and transmembrane electrical potential difference in liver mitochondria from hibernating, arousing and active ground squirrels have been compared. It is found that arousal from hibernation is accompanied by uncoupling which is mediated by two different mechanisms, one sensitive to cyclosporin A and the other suppressed by carboxyatractylate. Both uncoupling effects reach their maxima at 20 - 25 degrees C body temperatures. Involvement of an increase in the free fatty acid concentration in the arousal-induced uncoupling mechanisms is discussed.


Asunto(s)
Nivel de Alerta/fisiología , Atractilósido/análogos & derivados , Ciclosporina/metabolismo , Hibernación/fisiología , Mitocondrias Hepáticas/metabolismo , Animales , Atractilósido/metabolismo , Consumo de Oxígeno , Sciuridae
9.
Biokhimiia ; 56(5): 947-53, 1991 May.
Artículo en Ruso | MEDLINE | ID: mdl-1747420

RESUMEN

The parameters of energy coupling of mitochondria isolated from the livers of hibernating and awakening gophers were studied. The ATP/ADP-antiporter inhibitor carboxyatractylate slowed down the respiration rate, increased delta psi and decreased the ionic conductivity of the inner mitochondrial membrane as measured by the rate of the delta psi decline after addition of cyanide (in the presence of oligomycin and EGTA). A similar effect was produced by BSA, carboxyatractylate being fairly ineffective in the presence of BSA. In hibernating gophers the maximal rate of the uncoupled respiration and the ionic conductivity of the inner mitochondrial membrane were markedly decreased as compared with awakening gophers. The data obtained suggest that in awakening animals fatty acids induce the uncoupling of oxidative phosphorylation by the ATP/ADP-antiporter, this process being simultaneous with the activation of the respiratory chain.


Asunto(s)
Ácidos Grasos/metabolismo , Hibernación , Mitocondrias Hepáticas/metabolismo , Translocasas Mitocondriales de ADP y ATP/metabolismo , Animales , Atractilósido/análogos & derivados , Atractilósido/farmacología , Metabolismo Energético , Membranas Intracelulares/metabolismo , Mitocondrias Hepáticas/efectos de los fármacos , Fosforilación Oxidativa , Sciuridae , Albúmina Sérica Bovina/farmacología
10.
FEBS Lett ; 263(1): 73-6, 1990 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-2332054

RESUMEN

Electron transfer through the ubiquinol:cytochrome c1-segment of liver mitochondria isolated from hibernating ground squirrels Citellus undulatus is repressed by 70-80% as compared to mitochondria from the active animals. The inhibition site is likely to be localized between ubiquinone and the cytochrome bc1 complex. Partial release of the inhibition can be observed upon swelling of the isolated mitochondria in a hypoosmotic medium, the effect being prevented by phospholipase A2 inhibitors. Possible role of phospholipase A2 in regulation of ubiquinol oxidation by complex bc1 is discussed.


Asunto(s)
Reductasas del Citocromo/metabolismo , Hibernación , Mitocondrias Hepáticas/metabolismo , NADH Deshidrogenasa/metabolismo , Sciuridae/fisiología , Ubiquinona/análogos & derivados , Animales , Carbonil Cianuro m-Clorofenil Hidrazona/farmacología , Citocromos/metabolismo , Transporte de Electrón , Cinética , Mitocondrias Hepáticas/efectos de los fármacos , Mitocondrias Hepáticas/enzimología , Consumo de Oxígeno , Rotenona/farmacología , Ubiquinona/metabolismo
11.
Biokhimiia ; 55(2): 201-9, 1990 Feb.
Artículo en Ruso | MEDLINE | ID: mdl-2340313

RESUMEN

The rate of respiration and ATP synthesis in liver mitochondria (M) isolated from hibernating ground squirrels and incubated in the medium with normal tonicity (250 mosm) was shown to be considerably lower than the rate of respiration and ATP synthesis in liver M from active animals. The increase of the medium tonicity to 600 mosm simulated the state of M from hibernating animals, resulting in a decrease of the respiration rate of M from active ground squirrels. On the contrary, the decrease of the tonicity to 60 mosm caused the activation of the respiration and increase of the ATP synthesis in M from hibernating ground squirrels. Bromophenacylbromide (BPhB), an inhibitor of phospholipase A2, prevented the activation of the respiration of M from hibernating animals incubated in the medium with low tonicity. BPhB had practically no effect on the respiration of M from both hibernating and active ground squirrels as well as on the swelling of M in hypotonic medium. It was concluded that the activation of the respiration and increase of the ATP synthesis rate in M from hibernating ground squirrels incubated in the medium with low tonicity is related to the activation of phospholipase A2. It was assumed that decrease of phospholipase A2 activity and change in the lipid composition of mitochondrial membrane may be one of the reasons for inhibition of the respiration rate in M from hibernating ground squirrels.


Asunto(s)
Hibernación , Mitocondrias Hepáticas/metabolismo , Fosforilación Oxidativa , Consumo de Oxígeno , Sciuridae/metabolismo , Adenosina Trifosfato/biosíntesis , Animales , Cinética , Dilatación Mitocondrial , Concentración Osmolar , Oxidación-Reducción
12.
Zh Evol Biokhim Fiziol ; 25(6): 718-23, 1989.
Artículo en Ruso | MEDLINE | ID: mdl-2576170

RESUMEN

Studies have been made on the permeability of the inner membrane of the liver mitochondria from hibernating and active ground squirrels for succinate, glutamate, hydroxybutyrate and inorganic phosphate. The permeability was calculated from the rate of mitochondrial swelling in 100 mM ammonium salts of the substrates and phosphate. It was shown that the rate of mitochondrial swelling in hibernating animals is 2--3 times lower than in active ones, being essentially identical in a solution of ammonium phosphate. It was concluded that the permeability of the inner mitochondrial membrane for the substrates decreases in hibernating animals, remaining unaffected for phosphate. Calcium-induced activation of membrane phospholipase A2 facilitates the transport of oxidative substrates into the mitochondria of hibernating ground squirrels, significant increase in the mitochondrial respiration being simultaneously observed. The data obtained suggest that inhibition of transport of oxidative substrates is one of the main factors which account for a low respiration rate in the mitochondria of hibernating animals.


Asunto(s)
Glutamatos/metabolismo , Hibernación/fisiología , Hidroxibutiratos/metabolismo , Mitocondrias Hepáticas/metabolismo , Sciuridae/metabolismo , Succinatos/metabolismo , Ácido 3-Hidroxibutírico , Animales , Transporte Biológico/fisiología , Permeabilidad de la Membrana Celular/fisiología , Ácido Glutámico , Dilatación Mitocondrial/fisiología , Consumo de Oxígeno/fisiología , Fosfatos/metabolismo , Ácido Succínico
13.
Biull Eksp Biol Med ; 108(10): 488-90, 1989 Oct.
Artículo en Ruso | MEDLINE | ID: mdl-2597769

RESUMEN

The mechanisms for regulating the rate of respiration and oxidative phosphorylation in liver mitochondria from hibernating ground squirrels were studied. The microviscosity of the mitochondrial membrane in hibernating squirrels was found to be higher than that in active animals. Probably, a high microviscosity of the membrane causes a decreases in the rate of the transport of oxidation substrates into the mitochondrial matrix, which in turn may be one of the main reasons for the inhibition of mitochondrial respiration in hibernating squirrels. The activation of phospholipase A2 in a hypotonic medium results in the acceleration of the respiration and phosphorylation in the mitochondria from hibernating squirrels and is accompanied by the increase of the transport of substrates across the mitochondrial membrane. The inhibition of phospholipase A2 decreases Ca2+--induced acceleration of the transport of substrates and prevents the activation of the respiration and phosphorylation in a hypotonic medium.


Asunto(s)
Hibernación , Mitocondrias Hepáticas/metabolismo , Consumo de Oxígeno , Fosfolipasas A/fisiología , Fosfolipasas/fisiología , Animales , Células Cultivadas , Medios de Cultivo , Fosforilación Oxidativa , Fosfolipasas A2 , Sciuridae
14.
Zh Evol Biokhim Fiziol ; 25(4): 448-53, 1989.
Artículo en Ruso | MEDLINE | ID: mdl-2596204

RESUMEN

The state of adenylate system and intensity of oxidative phosphorylation in liver mitochondria of active and hibernating ground squirrels were studied depending on the concentration of extramitochondrial Ca2+ ([Ca2+]ex). It was shown that at [Ca2+]ex.10(-7) M, the content of ATP as well as ATP/ADP ratio are slightly lower in the mitochondria of hibernating ground squirrels than in the mitochondria of active animals. The other parameters of the adenylate system under the same conditions differ insignificantly. [Ca2+]ex increase to 10(-6) M has little effect on the parameters of the adenylate system of active animals. On the contrary, the mitochondria of hibernating ground squirrels are strongly affected: the level of ATP is 1.5-fold and the ratio of ATP/ADP is almost 2-fold decreased. At both [Ca2+]ex the intensity of oxidative phosphorylation is essentially higher in the mitochondria of active ground squirrels. With increasing [Ca2+]ex the rate of ATP synthesis decreases, and in the mitochondria of hibernating animals the decrease is more pronounced than in the mitochondria of active animals. Thus, oxidative phosphorylation and adenylate system of mitochondria from hibernating ground squirrels are more sensitive to [Ca2+]ex increase than those of the mitochondria of active animals.


Asunto(s)
Metabolismo Energético/fisiología , Hibernación/fisiología , Mitocondrias Hepáticas/metabolismo , Fosforilación Oxidativa , Sciuridae/fisiología , Adenosina Difosfato/metabolismo , Adenosina Monofosfato/metabolismo , Adenosina Trifosfato/biosíntesis , Animales , Calcio/metabolismo
15.
Comp Biochem Physiol B ; 94(3): 537-41, 1989.
Artículo en Inglés | MEDLINE | ID: mdl-2620498

RESUMEN

1. The rates of oxidation of various substrates (beta-hydroxybutyrate, succinate, ascorbate + TMPD) and the rate of ATP synthesis in liver mitochondria from active and hibernating ground squirrels were measured. 2. It was shown that the rate of mitochondrial respiration is significantly lower in hibernating animals than in active animals. 3. The degree of inhibition of mitochondrial respiration in hibernating ground squirrels was found to correlate with the length of the respiratory chain fragment involved in the oxidation of a given substrate. 4. The inhibition of mitochondrial respiration in hibernating animals was accompanied by a decrease in the rate of ATP synthesis. 5. The activity of phospholipase A2 in liver mitochondria from hibernating ground squirrels was found to be decreased. The activation of phospholipase A2 by Ca2+ ions eliminated the inhibition of respiration almost completely. 6. It was assumed that the inhibition of mitochondrial respiration during hibernation is (a) related to the suppression of phospholipase A2 activity and (b) caused by the reduced rates of electron transport through the respiratory chain and/or of substrate transport across the mitochondrial membrane.


Asunto(s)
Mitocondrias Hepáticas/metabolismo , Consumo de Oxígeno/fisiología , Sciuridae/metabolismo , Adenosina Trifosfato/biosíntesis , Animales , Calcio/fisiología , Dibucaína/farmacología , Ácidos Grasos no Esterificados/metabolismo , Hibernación/fisiología , Fosforilación Oxidativa , Fosfolipasas A/metabolismo , Fosfolipasas A2
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