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A very significant intracellular pool of calcium, sensitive to digitonin action and different from one of free cytozolic Ca2+, has been shown to exist in the cells of ciliate protozoan T. pyriformis. Calcium content in digitonin-sensitive pool NdigCa2+ has been estimated throughout the cell cycle in synchronized culture of T. pyriformis. The value of NdigCa2+ decreased in the period of time prior to and at the cell division, whereas after the division itself it increased. The possible role of the calcium content changes of digitonin-sensitive pool in regulation of cytozolic Ca2+ level and in control of cell division is discussed.

The effects of catecholamines on reactive oxygen species (ROS) generation by polymorphonuclear leucocytes were studied using chemiluminescence (CL). It has been found that catecholamines in 10(-9)-10(-10) M concentration range are able to increase reactive oxygen species generation. Within the micromolar concentration range (10(-6)-10(-5) M) cetacholamines (CA) strongly suppress CL intensity and ROS production. The efficiency of inhibitory action of CA: noradrenaline > adrenaline > dopamine > L-DOPA correspond to their redox properties. A conclusion is made that peroxidase is one of the main targets of CA effect.

The state of the oxidative phosphorylation system in intact and digitonin-treated BHK-21 cells in the lag-, logarithmic and stationary growth phases has been studied. It is shown that during the growth of cell culture the rates of oxygen uptake and the extent of coupling of oxidation and phosphorylation change significantly.

The paper deals with the effect of fasting on the content and transport of potassium ions in the rat liver mitochondria as well as on oxidative phosphorylation. It is shown that the concentration of potassium ions in the mitochondria under fasting lowers by 20-30% at an average as compared to the control. The rate of potassium ions release from the mitochondria in the presence of DNP also lowers. It is found that the respiratory control ratio after 24-h fasting decreases and increases after 48-h fasting. Possible reasons of changes in the transport of potassium ions in the rat liver mitochondria in fasting are discussed.

The content of potassium ions in rat liver mitochondria after intensive physical work (continuous swimming) is increased approximately 2-fold, while the rate of K+ efflux from the mitochondria is significantly reduced. A considerable increase of the "calcium capacity" and a decrease of the respiration rate in state 4 were found. The experimental results indicate that during intensive physical work the mitochondrial membrane resistance to the damaging effects is enhanced. A possible mechanism of these changes is discussed.

Transport of Pi into mitochondrial matrix induces K+-permeability of the membranes, which results from the addition of DNP. This induction of K+ efflux is eliminated by some agents causing the respiratory chain reduction (e.g. succinate, rotenone, antimycin A). It was shown that the abolition of the membrane potential is not sufficient for K+ efflux induction. The latter process is necessary for the energy-linked formation of the K+-transporting system. The lipid fraction containing lecithin and monophosphoinositol was extracted from the mitochondria after preincubation with Pi. The artificial bilayer membranes formed from these lipids are permeable for K+.

Additions of the fraction of outer mitochondrial membranes to the mitoplast suspension is shown to bring about an increase of the ADP-stimulated respiration rate, indices of respiration control and uncoupled respiration. This effect is not a result of the cytochrome c presence in the fraction of outer membranes. In the glycerol-containing medium which causes dissociation of intermembrane contacts the coupling effect of outer membranes on mitoplast respiration is not revealed. It is concluded that the outer membrane in contact with the inner one takes part in realization of the mitochondrial coupling.

The transmembrane potential (delta psi) of rabbit brain mitochondria was measured with the fluorescent dye dis--C2--5. During oxidative phosphorylation a fall in delta psi in the order of 20% was observed. In the presence of inhibitors of ATP synthesis, there was a good correlation between the fall in delta psi and the ADP-stimulated increase in respiration rate. The influence of endogenous calcium on the energetic metabolism of mitochondria was studied by measuring the changes of delta psi. An amount of 12 nmol Ca2+/mg protein cause half-inhibition of the ATP synthesis rate; 50 nmol/mg completely inhibits oxidative phosphorylation. The effect of the Ca2+ load on the ATPase activity of intact mitochondria was studied. It was found that endogenous calcium inhibits in a similar degree synthesis and hydrolysis of ATP. It was shown that both Ca ATP and Mg ATP can serve as a substrate for the mitochondrial ATPase.

The effect of spermine (50-400 microM) on the Ca-transporting system of brain mitochondria was studied. In a medium containing Mg2+ and ATP, spermine facilitates the accumulation of Ca2+ by decreasing Km of the uniporter. Spermine inhibits Na-stimulated Ca2+ efflux; this effect is dependent on the ionic strength of the medium--it is decreased when KCl concentration is increased from 20 to 120 mM. Spermine (200 microM) decreases (by 50%) the steady state concentration of Ca2+ maintained by mitochondria. The importance of spermine as a regulator of Ca2+-transport in brain mitochondria is discussed.

Electrical properties of BLM formed from lipid components of rat liver mitochondria were studied. The lipids were obtained after preliminary 40 second incubation of mitochondria in the medium containing succinic acid. BLM electroconductivity in the medium with calcium chloride (8--20 mM) is 10--100 times higher than the initial electroconductivity in tris-HC1 at pH 7.5, and in the presence of potassium chloride and magnesium chloride it differes little from the initial value. The transmembrane potential difference per 10-fold concentration gradient of Ca2+, Mg2+, and K+ is approximately 27 mV, approximately 15 mV and approximately 22 mV correspondingly. By means of biionic potential method the following selectivety line for cations is formed: Ca2+ greater than Sr2 greater than or equal to Mg2+ greater than K+. La3+ ions inhibit the transport of Ca2+ through the BLM studied.