[The effect of the homogenates from different developmental stages of the nematode Protostrongylus rufescens (Leuckart, 1895) on mitochondrial and lipid bilayer membranes].

The effect of the homogenates from different developmental stages of the nematode Protostrongylus rufescens on mitochondrial and lipid bilayer membranes has been studied. The homogenate of P. rufescens affects efficiently the cell energy by the inhibition of the mitochondrial respiration in the metabolic state V3, uncouples oxidative phosphorylation and affects the functions of mitochondria at the level of cyclosporine A-sensitive pore by making it highly permeable. Moreover, the nematode homogenate at the concentration of 1 mkg/ml increases efficiently the integral permeability of lipid bilayer membranes. An increase in this permeability is connected apparently with the formation of single ion channels. The channels of lipid bilayer membranes induced by the nematode homogenate show cation selectivity.

[Effects of glycyrrhetic acid on transmitter secretion]. / Effekty glitsirretovoi kisloty na protsess sekretsii mediatora.

The investigation of the effects of glycyrrhetic acid on spontaneous secretion of transmitter from neurotermination of the frog neuromuscular synapses showed that this substance, unlike glycyrrhizic acid, increased the frequency and amplitude of m. e. p. p. in a dose-dependent manner. The effect of glycyrrhetic acid is observed in calcium-free solution which may indicate ability of glycyrrhetic acid to mobilize calcium from inner cell pools. The effects of glycyrrhetic acid, in particular increasing the frequency of the m. e. p. p., testify that glycyrrhetic acid acts on the level of presynaptic membrane.

[Menadione induction of Ca2+ efflux from the mitochondria and of mediator secretion from the nerve endings]. / Induktsiia menadionom vykhoda Ca2+ iz mitokhondrii i sekretsii mediatora iz nervnykh okonchanii.

It is shown that menadion increases the rate of Ca2+ efflux from mitochondria which decreases in the presence of ditiotreitol. Menadion at concentration of 50 microM induces Ca2+ efflux from mitochondria and its effect on synaptic transmission is discussed.

[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]. / Reguliatsiia tireoidnymi gormonami vzaimodeistviia mitokhondrii s nizkomolekuliarnymi tsitoplazmaticheskimi mediatorami, indutsiruiushchimi fosfatzavisimyi transport ionov K+ i H+ cherez membranu mitokhondrii.

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.

[Effect of oxaloacetic acid on hydrogen-calcium metabolism in mitochondria]. / Deistvie shchavelevouksusnoi kisloty na vodorodno-kal'tsievyi obmen v mitokhondriiakh.

It has been shown by using o-phthalic acid--a concurrent inhibitor of the transport of oxalacetic acid in mitochondria that the effect of the latter on the mechanism of 2H+/Ca2+-metabolism is realized at the inner side of the inner mitochondrial membrane. Oxalacetic acid was shown to induce not only the release of Ca2+ ions but also those of strontium and manganese accumulated in the mitochondria (100-150 nmol/mg of protein). Mechanism of the effect of oxalacetic acid on permeability of the mitochondria membranes are discussed.

[Role of protonophore activity of oxalacetic acid in inducing Ca2+ yield from mitochondria]. / Rol' protonofornoi aktivnosti shchavelevouksusnoi kisloty v indutsirovanii vykhoda Ca2+ iz mitokhondrii.

It has been found earlier in Lehninger's Laboratory [24] that oxidation of endogenous PN mitochondria induced by oxalacetic acid (OAA) brings about the release of accumulated Ca2+. Analysis of possible mechanism of this phenomenon has shown that OAA has protonophore activity on mitochondria and BPM unlike the malate--the product of enzymic reduction of OAA in the presence of NAD . H. OAA-induced permeability of BPM and mitochondria membranes for H+ is observed at pH 7.5-8.0 and is insignificant at pH 7.0 and lower. Possible function of OAA as a soft uncoupler-protonophore controlled by metabolism is discussed, in particular--in connection with Ca2+ transport in mitochondria.