[The effect of Cd2+ on the respiration and swelling of isolated rat liver mitochondria in incubation media of different compositions].

We studied a change in Cd2+ influence on state 4 and 3 respiration and on 2,4-dinitrophenol (DNP)-stimulated respiration of isolated rat liver mitochondria, after replacement of KCl for equimolar quantities of NaCl, LiCl or for 200 mM sucrose in the incubation medium. Cd2+ concentrations higher than 2.5 microM reduced state 3 respiration or DNP-stimulated one in KCl medium (control), and activated state 4 respiration, however, at Cd2+ concentrations higher than 12.

[Changes in the effect of Cd2+ on the respiration of isolated rat liver mitochondria after their preincubation with Ca2+, Sr2+, Ba2+, Mn2+ and ruthenium red].

Action of Cd+ on mitochondrial respiration is decreased by some bivalent ions, however the reason of this still remains obscure. Change of Cd2+ action over a wide range of its concentrations on respiration of rat liver mitochondria in states 4, 3 and in the presence of 2, 4-dinitrophenol (DNP) after mitochondrial preincubation with Ca2+, Sr2+, Ba2+, Mn2+ or ruthenium Red (RR) was studied in vitro. In the control (experiments without preincubation), Cd2+ lowers mitochondrial respiration in state 3 as well as that in the presence of DNP, and increases the respiration in state 4.

[The effect of anoxia and energy metabolism inhibitors on potassium and sodium homeostasis in the neurons of the gastropod mollusk].

Anoxia and inhibitors of energy metabolism have been studied for their effect on intracellular K and Na concentrations, membrane potential, conductivity, passive and active ouabain-sensitive transport of potassium (86Rb) in neurons of freshwater snail Planorbarius corneus. The X-ray microanalysis has shown that anoxia caused no changes in K and Na concentrations in neurons. NaCN inhibited oxygen uptake by ganglia, but has actually no effect on the membrane potential, conductivity and 86Rb uptake in neurons.

[The isomorphism of univalent thallium and potassium in membrane transport processes].

Thallium ions (T1+) are able to isomorphous replacement of K+ in various minerals. The similarity between. T1+ and K+ is based upon the closeness of their crystal radii, hydration energy and mobility in aqueous solutions.

[The transport of univalent thallium across the human erythrocyte membrane].

Transport of 204Tl was studied in human erythrocytes incubated in isotonic salt solutions at pH 7.4 and 37 degrees C. 204Tl was rapidly accumulated in cells up to the constant level within a 10 minutes incubation (t0.

[Effect of sodium, lithium and amiloride on the K+-dependent phosphatase activity of membrane preparations of Na,K-ATPase].

Effects of sodium, lithium and amiloride on the ATPase reaction and on its potassium-dependent step were studied using membrane preparations of Na,K-ATPase. It was established that the addition of 70 mM NaCl or LiCl to the reaction medium diminished the hydrolysis of para-nitrophenyl phosphate (pNPP) by 70 and 40%, respectively. Amiloride (0.

[Effect of inhibitors of energy metabolism on potassium accumulation in the neurons of the mollusk Planorbarius corneus].

Studies have been made of the effect of inhibitors of energy metabolism on maintenance of Na and K concentrations, as well as on accumulation of Rb (as an analogue of K) in single neurones of the mollusc P. corneus. Concentrations of Na, K and Rb in cells were determined by X-ray spectral microanalysis.

[Transport of univalent cations across the erythrocyte membrane of hypertensive rats of various ages].

In the erythrocytes incubated at low temperature (3-6 degrees C), the uptake of Li+ in 6- and 16-week old spontaneously hypertensive rats (SHR) was significantly higher than in the normotensive rats (WKY) of the same age. During the incubation of cells at 37 degrees C no difference occurred in either ouabain-sensitive or ouabain-resistant fluxes of Rb+, Na+ and Li+ between the 16-week old SHR and the WKY. K+ efflux from the erythrocytes at 3 degrees C was consistently stimulated after addition to the incubation medium of 1 mmol/l Ca2+.

[Effect of cadmium ions on the respiration, cation transport and morphology of the liver mitochondria in the rat and the lamprey].

The influence of Cd2+ on the function and structure of liver mitochondria of rats and lamprey (Lampetra fluviatilis L.) has been studied in vitro. It is shown that Cd2+ can penetrate into the mitochondrial matrix due to Ca2+-transport mechanism.

[Effect of energy metabolism on the ionic selectivity of the K+ center of the Na+/K+ pump in the skin of the frog].

The uptake of Rb+ and Tl+ in frog skin incubated in saline containing 86Rb and 204Tl was studied. The ratio of ouabain-sensitive influxes Tl+/Rb+ = 2. Inhibition of the unidirectional transport of Na+ by rotenone or by Tl+ was not accompanied by the total decrease in the ouabain-sensitive uptake of Rb+ and Tl+.

[Cadmium accumulation in tissues of the mussel Mytilus galloprovincialis].

Studies have been made on cadmium accumulation in tissues of mussels kept within 20-60 days in water artificially enriched by Cd up to 20-100 micrograms/l. Irrespectively of cadmium concentration in the medium, its accumulation in tissues decreases in the following order: mid-gut gland, gills, gonads, mantle, adductor. Maximum concentration of Cd was found in the digestive tubuli of the mid-gut gland by X-ray microanalysis.

[The rate of outflow of penetrating cations does not depend on the energy state of mitochondria].

Inhibiton of respiration at 0 degrees C believed to decrease the membrane potential in mitochondria did not lead to a substantial acceleration of the efflux of penetrating cations (triphenylmethylphosphonium, Cs- valinomycin). On the contrary the energy-dependent influx of the cations was rapidly inhibited indicating that there was no prolonged delay in the membrane deenergization. Low sensitivity of the cation efflux to respiration inhibition suggests under the conditions studied the metabolic component of the membrane potential to be rather small.

[Action of the salts of univalent thallium on the liver mitochondria of the rat].

Using light scattering and electron microscopic techniques, studies have been made of the swelling of liver mitochondria in isotonic sucrose solutions containing different concentrations of nitrate or acetate of monovalent thallium. It was concluded that the injurious effect of thallium on the mitochondria is associated with both its penetration into intramitochondrial space, and interaction of the external thallium with mitochondrial membranes.

[Sodium and potassium ion transport in the skin of Rana temporaria frogs under anaerobic conditions].

Saturation of incubation media with argon completely inhibits the unidirectional transport of Na+ across the frog skin while the ion composition of the skin cells does not change at all. The maintenance of the intracellular concentrations of Na+ and K+ cannot be explained by an assumption that at anaerobic conditions the cell membrane permeability to monovalent cations is markedly decreased. For instance, an addition of ouabain to the serosa bathing medium saturated with argon results in increasing the intracellular concentration of Na+ and loss of cell K+ indicating that both Na+ and K+ can freely diffuse across the cell membrane down to their electrochemical gradients.

[Effect of thallium ions on sodium and potassium transport in frog skin].

It has been shown that Tl+ accumulated in the frog skin cells (Rana temporaria) inhibits irreversibly the unidirectional transport of Na+ estimated by the short circuit current (SCC). The inhibiting effect of Tl+ cannot be attributed to a decrease of Na+ penetration through the apical membranes. The influx of 22Na+ from mucosal bathing solution into the skin poisoned with Tl+ was about 50% of that observed in the intact skin, while the SCC was completely inhibited.

[Active transport of triphenylmethylphosphonium in mitochondria].

Energy-dependent accumulation of triphenylmethylphosphonium (TPMP+) in rat liver mitochondria at 0 degree C is only 30-50% less than that observed at room temperature, while the rate of TPMP+ penetration drastically decreases enabling accurate studying of transport kinetics. Potassium diffusion potential accelerates the influx of TPMP+ and decreases the efflux rate in agreement with the expected behaviour of penetrating cations diffusing along or against an electric field. On the contrary, energization of mitochondria supposed to generate the metabolic membrane potential increases only the influx rate of TPMP+ without affecting the efflux of the cation.

[Effect of valinomycin and nonactin on monovalent cation transport in mitochondria].

Unidirectional fluxes of tracers 137Cs+ (+valinomycin) and 204Tl+ (+nonactin) in mitochondria maintained under stationary state at 0 degree C have been studied. The tracer uptake in energized mitochondria (Q infinity Cmit/Cmed = Kin/kout) was about 10 times as high compared to that in a deenergized state. Energization caused a 5-10 fold increases of the influx rate constant kin, while the efflux rate constant, kout, decreased only by 1.

[Effect of thallium on enzyme activity and unidirectional sodium transport in frog skin].

The cytophotometric analysis of enzyme activity in the frog skin epithelium has shown that Tl+ accumulated by cells at millimolar concentrations causes a 70-80% inhibition of both succinate and alpha-ketoglutarate dehydrogenases, while the activity of Na, K-ATPase decreased only slightly. The opposite situation was true for the ouabain treatment. The accumulation of Tl+ by frog skin caused a substantial swelling of mitochondria.

[Effect of the structural integrity of Na,K-ATPase preparations on the ability of lithium to substitute for sodium in enzyme activation].

The ability of Li+ to substitute for Na+ in activating ouabain-sensitive ATPase of the rat kidney was studied on three kinds of the enzyme preparation: a) crude membrane fraction, b) purified enzyme, c) tissue slices. The preparations were free of endogenous Na+ and K+. The ATPase activity of slices was estimated both biochemically and cytochemically.

[Erroneous use of lipophilic phosphonic cations for determining mitochondrial membrane potential].

The energy-dependent accumulation of triphenylmethylphosphonium (TPMP+) in rat liver mitochondria at 0 degrees C is less than that at a room temperature only by 30-50%, while the cation penetration rate drastically decreases thus making possible an accurate studying of the transport kinetics. It is shown that K+-diffusion potential accelerates the influx of TPMP+ and decreases the efflux rate in full agreement with the expected behaviour of a penetrating cation diffusing along or against the electrical field. On the contrary, the energization of mitochondria, which has been generally believed to generate a metabolic membrane potential, caused only a stimulation of the influx of TPMP+ without affecting the efflux rate.