[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.

[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+.

[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.

[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.

[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.

[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.