[Acetylcholine and effectiveness of oxidative phosphorylation in isolated rat hepatocytes]. / Atsetylkholin i efektyvnist' okysnoho fosforyliuvannia izol'ovanykh hepatotsytiv shchuriv..

It is shown that ADP and DNP does not intensify the respiration rate in hepatocytes of rats obtained by means of trypsin or EDTA. The same cells obtained using collagenase, phosphorylate added ADP and increase the respiration rate after DNP addition. Acetylcholine added to the cell suspension in a dose of 5 x 4 x 10(-8) M) increases the efficiency of oxidative phosphorylation. The scheme of neurotransmitter regulation of intensity of respiration and efficiency of oxidative phosphorylation on the cell level is suggested.

[Role of calcium ions in the mechanism of action of acetylcholine on energy metabolism in rat liver mitochondria]. / Rol' ioniv Ca mekhanizmi diï atsetylkholinu na enerhetychnyi obmin v mitokhondriiakh pechinky shchura.

It is shown that administration of acetylcholine to animals (50 micrograms per 100 g of body weight) leads to the activation of respiration and oxidative phosphorylation in the rat liver mitochondria under oxidation of alpha-ketoglutarate; this effect depends on the concentration of calcium ions in the incubation medium of mitochondria. The rate of ADP-stimulated respiration of mitochondria of experimental animals reaches its maximum level under lower concentrations of Ca2+ than in the control animals. The results of investigation of dependence of acetyl choline effect on respiration of mitochondria on the concentration of alpha-ketoglutarate in calcium and calcium-free incubation medium have shown that the half-maximum effect of acetylcholine is observed in calcium medium at lower concentration of the substrate than in calcium-free medium. The latter indicates to the increase of affinity of alpha-ketoglutarate dehydrogenase to alpha-ketoglutarate under these conditions. It is found out that acetylcholine (1.10(-8) M) increases the rate of ADP- and Ca(2+)-stimulated respiration of mitochondria of isolated perfused rat liver, while mutual effect of verapamyl and niphedipin removes this effect.

Adenosine improves cardiomyocyte respiratory efficiency.

The role of adenosine on the regulation of mitochondrial function has been studied. In order to evaluate this the following experiments were done in isolated rat cardiomyocites and mitochondria using polarographic techniques. Cardiomyocyte oxygen consumption (MVO2) and mitochondrial respiratory function (State 3 and State 4, respiratory control index, and ADP/O ratio) were evaluated after exposure to adenosine. Cardiomyocyte MVO2 was significantly lower in cells previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) than in cells not exposed to adenosine (control). Addition of dipyridamole (10 microM) or 8-(p-Sulfophenyl) theophylline (50 microM) to cardiomyocytes before adenosine incubation prevented the adenosine-induced changes in MVO2. Mitochondria obtained from isolated perfused beating heart previously perfused with adenosine (10 microM, 30 min heart perfusion) also resulted in significant increases in ADP/O and respiratory control index compared to matching control. Mitochondria isolated from cardiomyocytes previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) resulted in a significant increase in mitochondrial ADP/O ratio compared to control. Adenosine-induced decrease in cardiomyocyte MVO2 may be related to an increase in efficiency of mitochondrial oxidative phosphorylation, and more economical use of oxygen, which is necessary for survival under ischemic stress.

[Mechanism of reciprocal effects of acetylcholine on oxidation of alpha-ketoglutarate and succinate in heart and liver mitochondria. Factors influencing detection of the acetylcholine effect]. / Mekhanizm retsiproknoï diï atsetylkholinu na okysneniia alpha-ketohlutaratu i suktsynatu v mitokhondriiakh sertsiia i pechinky. Faktory, shcho vplyvaiut' na vyiavlennia efektu atsetylkholinu.

Effect of acetylcholine administration (50 mg/100 g) on phosphorylating oxidation in the liver and heart mitochondria of rats and guinea pigs has been studied. The reciprocal effect of acetylcholine on alpha-ketoglutarate and succinate oxidation (acceleration and inhibition, respectively) was observed. In both cases, the ADP/O coefficient increased. The effect was specific for two substrates and was absent when pyruvate, isocitrate, malate and glutamate were oxidized. When a mixture of glutamate and malate was oxidized producing alpha-ketoglutarate by transamination, acetylcholine stimulated respiration and that effect was abolished by aminooxyacetate. The extent of acetylcholine effects depended on the substrate concentration, duration of storage of isolated mitochondria, the type of the tissue and species of an animal. The described increase in oxidative phosphorylation efficiency by acetylcholine administration corresponded to physiological action of the blood and tissue acetylcholine in the organism which promoted saving of oxygen consumption.

[EFFect of alpha-ketoglutarate and acetylcholine synergism on energy metabolism in mitochondria]. / Sinerhism dii alpha-ketohlutaratu i atsetylkholinu na enerhetychnyi obmin v mitokhondriiakh.

The influence of Na alpha-ketoglutarate intraperioneally injected in dose of 20 mg per 100 g of body weight on substrate oxidation in the rat liver and heart mitochondria, cholinesterase activity in the blood, liver and pancreas and acetylcholine level in the rat liver and pancreas has been studied. Alpha-ketoglutarate is found to have a pronounced reciprocal effect on intramitochondrial alpha-ketoglutarate and succinate oxidation (acceleration and inhibition, respectively). The effect of Na alpha-ketoglutarate is specific for the two substrates as it is absent when another substrate of the tricarboxylic acid cycle is oxidized. This selective influence on substrate oxidation is realized by means of activation of aminotransferase reaction, which lead to alpha-ketoglutarate production by transamination. This effect is almost the same as in case of acetylcholine injection and exceeds it for the value of some energy parameters. It is supposed that influence of Na alpha-ketoglutarate on energy metabolism is realized by means of cholinesterase inhibition and of acetylcholine level increase. The stimulation effect on oxidative phosphorylation is mostly expressed in case of joint injection of Na alpha-ketoglutarate and acetylcholine. It is supposed that Na alpha-ketoglutarate is a synergist to acetylcholine.

[The effect of hypoxic hypoxia on energy metabolism in the liver mitochondria and the acetylcholine content of different tissues]. / Vplyv hipoksychnoï hipoksiï na enerhetychnyi obmin u mitokhondriiakh pechinky ta vmist atsetylkholinu v riznykh tkanynakh.

It has been found, the 1 or 2 days exposure of animals to hypoxic hypoxia (during 4 hours every day; 32 mm Hg) leads to the decrease of acetylcholine level in rat heart, liver and pancreas tissues and to activation of succinate oxidation in rat liver mitochondria. Beginning from the 7th day of hypoxia treatment the level of acetylcholine in the tissues was increasing and it was connected with the activation of NAD-dependent substrate alpha-ketoglutarate oxidation in the rat liver mitochondria and with the increase of the efficiency of oxidative phosphorylation. The effect increases to the 12-16-th day of animal adaptation. The important role of acetylcholine in formation of nonspecific adaptation reactions of organism to hypoxia has been shown.

[The effect of the parenteral administration of alpha-ketoglutarate on the resistance of rats to ionizing radiation and on their cholinergic systems]. / Vplyv parenteral'noho vvedennia al'fa-ketohlutaratu na rezystentnist' shchuriv do ionizuiuchoho oprominennia ta kholinerhichnu systemu ïkh orhanizmu.

We have investigate the effect of sodium ketoglutarate intraperitoneal injection (20 mg/100 g body weight) made 0.5 hour before and 1, 2 and 3 hours after total X-ray treatment (259 mKl/kg) on the survival of rats. Simultaneously we have define changes in cholinesterase-acetylcholine system and content of adrenaline and noradrenaline in liver and pancreas tissues, small intestines mucous and in blood. All the data were taking at 1, 2, 5, 4, 24 and 72 hours after treatment and sodium ketoglutarate injection. We have found that sodium ketoglutarate injection made 0.5 hour before the treatment results in increasing of percentage death rate and injection made 1 and 2 hours after treatment results in increase in survival of rats. The effect of alpha-ketoglutarate injection made 1 hour after treatment in more pronounced. It is accompanied with increase of cholinergic status of organism on the catecholamine deficit background, decrease in the cholinesterase activity and increase of acetylcholine content in tissues of treated organism.

[Adrenergic and cholinergic regulation of respiratory efficiency of secretory cells]. / Adrenerhichni ta kholinerhichni mekhanizmy rehuliatsii efektyvnosti dykhannia sekretornykh klityn.

The influence of sympathetic and parasympathetic systems on the secretory cell respiration is mediated at the subcellular level by adreno- and cholinoreceptors of plasmatic membranes and is related to selective oxidation of two different substrates of the Krebs cycle: succinate and alpha-ketoglutarate, both being involved into two reciprocal mediator-hormonal-substrate-nucleotide systems: catecholamines-succinate-cAMP-ATP and acetylcholint-alpha-ketoglutarate-cGMP-GTP. The reciprocation of these systems is necessary for regulation of cell oxygen demand and effective oxygen utilization for ATP-synthesis and synthesis of other macroergical compounds depending on the functional state of a cell.