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M Kh Gaĭnutdinov

Publications and source records attributed to M Kh Gaĭnutdinov.

At least 19 recordsLinked to original sources
PubMed1994

[A calcium channel in the rat liver inner mitochondrial membrane. Effective diameter and selectivity under various conditions].

The pore with an effective diameter of 6.0 A is a Ca(2+)-channel of the inner mitochondrial membrane. Transport of nonelectrolytes through the pore is inhibited by ruthenium red, a specific Ca2+ transport inhibitor, and by polyanions which bind to the positively charged regions in the pore localized on the outer side of the inner mitochondrial membrane. The selectivity of Ca2+ ion transport into intact mitochondria is due to the binding of Ca2+ ions by the glycoprotein at the mouth of the pore as well as to electrostatic interactions of monovalent cations (electrostatic repulsion) and Cl- ions (strong binding) with the positively charged region of the ion-selective filter of the pore. Under normal conditions SCN- and NO3- ions are transferred through the pore at a high rate. Removal of Mg2+ ions and the rise in pH diminish the electrostatic repulsion of the monovalent cations and Cl- ions from the positively charged region of the pore. Depending on conditions, the pore can function as a monovalent ion transport system or as a mechanism of Cl- ion transfer through the inner mitochondrial membrane.

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PubMed1993

[Oxidative phosphorylation uncoupling in hyperthyroidism as a result of activating cyclosporin-sensitive pores in the inner mitochondrial membrane by water soluble modulators from rat liver cytoplasm].

Small concentrations of low molecular weight modulators of the functional state of rat liver cytoplasm mitochondria, which uncouple oxidative phosphorylation, induce phosphate-dependent transport of potassium and hydrogen ions. In contrast, high concentrations of these compounds induce nonspecific transport of monovalent cations and sucrose (K+ > H+ > Na+ > or = Li+ > sucrose). The effect of cytoplasmic modulators on oxidative phosphorylation and permeability of the inner mitochondrial membrane in inhibited by cyclosporin A and controlled by physiological concentrations of Ca2+. It is assumed that ion transport across the inner mitochondrial membrane in the presence of cytoplasmic modulators is implemented by the same cyclosporin-sensitive transport system which in damaged mitochondria functions as a nonspecific pore.

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PubMed1992

[Effective diameter of pores in rat liver mitochondria inner membrane and selectivity of transport of monovalent cations with a submicromolar concentration of Ca2+ ions or A23187 and EDTA].

Studies of swelling of rat liver mitochondria in isoosmotic solutions of nonelectrolytes in the presence of respiration inhibitors revealed that submicromolar concentrations of Ca2+ increase the diameter of pores in the inner mitochondrial membrane--from 5.5-6.0 A (10(-8) M Ca2+) up to 7.5 A (3 x 10(-7) M Ca2+) and 8.0-8.5 A (6 x 10(-7) M Ca2+); these increases are prevented by cyclosporin A. The inner mitochondrial membrane with an effective pore diameter of 7.5 A is readily permeable for potassium but not for sodium ions, although with an increase in the effective pore diameter up to 8.0-8.5 A the selectivity of the K(+)-Na+ channel decreases. A conclusion is drawn that in the presence of submicromolar concentrations of Ca2+ the conductivity of the cyclosporin-sensitive pore for monovalent cations increases in the following order: K > Na > Li.

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PubMed1990

[Regulation of thyroid hormones of the interaction of mitochondria with low-molecular weight cytoplasmic mediators, induced by phosphate- dependent transport of K+ and H+ ions through the mitochondrial inner membrane].

In vivo thyroid hormones control the binding to mitochondria of low molecular weight water-soluble cytoplasmic mediators that are capable to induce oxidative phosphorylation uncoupling, by increasing the sensitivity of mitochondria to the effects of these mediators. In hyperthyroid rat liver mitochondria cytoplasmic mediators stimulate the phosphate-dependent transport of K+ and H+ in a greater degree than in liver mitochondria of control rats. The increase in the oxidative phosphorylation uncoupling by cytoplasmic mediators is one of mechanisms of thermogenesis stimulation by thyroid hormones.

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PubMed1990

[Isolation of low molecular weight cytoplasmic regulators from the rat liver inducing the electrophoretic transport of K+ ions and phosphate across the inner mitochondrial membrane].

A water-soluble thermostable factor from rat liver cytoplasm whose activity decreases during starvation, causes the uncoupling of oxidative phosphorylation and stimulates pyruvate oxidation in rat liver mitochondria. The activity of this factor is insensitive to pronase treatment. Gel filtration and ion-exchange chromatography resulted in three low molecular weight water-soluble fractions which bear a negative charge at alkaline values of pH and induce electrophoretic transport of K+ and phosphate across the inner mitochondrial membrane. The effect of this factor on K+ transport is manifested at pH less than or equal to 7.0, that on phosphate transport-at pH 6.5-7.6.

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PubMed1988

[Regulation of oxidative phosphorylation, K+ ions transport and the volume of mitochondrial matrix by cytoplasmic glycopeptide and Ca2+ ions].

A thermostable low molecular weight glycopeptide containing syalic acids, which uncouples mitochondrial oxidative phosphorylation, has been detected, isolated and purified from rat liver cytoplasm. In the presence of the glycopeptide, oxidative phosphorylation in rat liver mitochondria is uncoupled by low physiological concentrations of Ca2+, which otherwise do not have any appreciable effect on the mitochondria. Oxidative phosphorylation uncoupling by the glycopeptide is accompanied by an increase of the mitochondrial volume. This process has a limited amplitude and is regulated by changes in Ca2+ concentration in the extramitochondrial space. The glycopeptide has been shown to induce K+ transport across the inner mitochondrial membrane, this effect is enhanced by Ca2+.

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PubMed1985

[Electrogenic transport of bicarbonate ions through the internal mitochondrial membrane induced by cytoplasmic glycopeptide].

Cytoplasmatic glycopeptide-induced bicarbonate ion electrogenic transport through mitochondrial membrane has been studied. Glycopeptide, described earlier as a factor increasing inner mitochondrial membrane permeability for phosphate ions, has been also shown to induce bicarbonate ion electrogenic transport through inner mitochondrial membrane. HCO3- ion transport, induced by cytoplasm glycopeptide is realized by pH-dependent pore. The interrelation of cytoplasm glycopeptide with mitochondria is regulated by mitochondrial energization.

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PubMed1984

[Induction of electrogenic phosphate transport through the mitochondrial membrane by a thermostable cytoplasmic factor in hyperthyroidism].

Addition of a thermostable cytoplasmic fraction leads to the uncoupling of oxidative phosphorylation of the mitochondria. In hyperthyrosis such an effect manifests itself more powerfully than in the control. Addition of the thermostable cytoplasmic fraction induces electrogenic phosphate transport via the mitochondrial membrane. In hyperthyrosis, the activity of the thermostable inducer of phosphate transport in the cytoplasm increases. The functioning of the phosphate cycle may be the cause of the uncoupling of oxidative phosphorylation of the mitochondria during the disease in question.

Animals↗
PubMed1983

[The role of insulin-dependent cytoplasmic regulator in carbohydrate metabolism during immobilization].

Immobilization decreased the activity of insulin-dependent cytoplasmatic regulator in the rat liver. Cessation of the immobilization resulted in increment of insulin--dependent cytoplasmatic regulator activity in liver and diaphragm. After the immobilization the glycogen content is considerably higher in the liver, which seems to be due to an increase in the regulator activity. The restoration after the immobilization leads to a decrease in hypoglycemic action of insulin in vivo and in insulin-dependent cytoplasmatic regulator action in vitro.

Animals↗
PubMed1983

[Regulation of pyruvate transport in mitochondria by thyroid hormones].

During thyroidectomy, the stimulating action of the catalytic amounts of a thermostable fraction of rat liver and diaphragm cytoplasm on Ca2+ transport in mitochondria, which indicates the decrease of the activity of an insulin-dependent cytoplasmic regulator (IDR) in insulin target organs. Thyroidectomized rats also manifested a decrease in blood insulin and glucose concentrations. Administration of the physiological doses of thyroxine produced an increase in both blood glucose concentration and IDR activity in the liver and diaphragm of thyroidectomized rats. Experiments with measuring the kinetics of the swelling of deenergized mitochondria in isoosmotic solution of ammonium pyruvate demonstrated the inhibition of liver mitochondrial swelling in thyroidectomized rats.

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PubMed1982

[Effect of thyroidectomy and hyperthyroidism on Ca2+/2H+-antiporter activity in rat liver mitochondria].

The manifestation of Ca2+/2H+ antiporter activity in rat liver mitochondria was shown to be inhibited in thyroidectomy and stimulated in hyperthyroidosis. Experiments with measuring the kinetics of the swelling of deenergized mitochondria in isoosmotic solutions Ca (NO3)2, pH 8.1 demonstrated inhibition of the swelling of liver mitochondria during thyroidectomy and stimulation because of administering thyroid hormones in vivo. During thyroidectomy, the phosphate-induced swelling of rat liver mitochondria was powerfully inhibited. Meanwhile administration of thyroxine to rats stimulated the swelling of mitochondria.

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PubMed1982

[Insulin-dependent cytoplasmic regulator activity in the rat liver and heart in fasting and muscle work].

Upon starving and muscle work the activity of an insulin-dependent cytoplasmic regulator (IDR) in the rat liver has been demonstrated to be lowered. This is one of the mechanisms of glycogenolysis and gluconeogenesis stimulation. Rapid increase in IDR activity in the heart and liver has been recorded in the period of recovery after swimming, with the increase being more intense in the heart. It has been shown that in the heart the resynthesis of glycogen proceeds more rapidly than in the liver. Therefore, the rate of glycogen resynthesis by the liver and heart correlates with IDR activity.

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PubMed1981

[Inhibition of gluconeogenesis in the kidneys by a cytoplasmic regulator of mitochondrial membrane permeability].

Cytoplasmatic glycoprotein previously shown to be an inhibitor of mitochondrial membrane permeability for oxidation substrates inhibits in-vitro gluconeogenesis from pyruvate, lactate, succinate, alpha-ketoglutarate and glutamate in slices of the renal cortical layer. The inhibition was reduced with Ca2+ concentration increase in the incubation medium from 0.02 to 2 mM.

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