Biomedical subjects

S V Konev

Publications and source records attributed to S V Konev.

148 records · Page 9Linked to original sources

PubMedDate not supplied

[Effect of ischemic damage factors on lipid peroxidation in rat brain synaptosomes].

Accumulation of TBA-reactive substances after a 40 min incubation of rat brain synaptosomes at 37 degrees C was analysed. A lowering of pH to 6.5-5.5 or arachidonic acid (0.1-1.0 mM) increased lipid peroxidation which was blocked by antioxidants. Acidosis (pH 6.0) and arachidonic acid used in combination had a strong synergic effect. Depolarisation of plasma membranes or intrasynaptosomal mitochondria were without influence on lipid peroxidation at neutral or acid pH. The results support a leading role of acidosis and phospholipases in stimulation of peroxidation under ischaemia.

Animals↗

PubMedDate not supplied

[Effect of acidosis on membrane potential and calcium transport in rat brain synaptosomes].

The influence of acidosis on the transmembrane potential, sodium pump and membranous systems of calcium transport was studied on isolated presynaptic nerve terminals (synaptosomes) from rat brain. It is established that acidic shift causes a decrease of membrane potential, a large inhibition of the sodium pump (by three times at pH 6.0). All the systems controlling both inward- and outward-directed calcium fluxes are partially blocked by low pH. At pH 6.0 the basal influx and calcium pump are reduced two-fold while the voltage-sensitive calcium channels and Na+/Ca2+ exchanger are inhibited by three and four to five times, respectively. We have no found any evidence of acidosis-induced net flux of calcium directed inwards.

Acidosis↗

PubMedDate not supplied

[Luminescence study of the effect of temperature on the conformational state of fibrinogen].

Results are presented of measuring fibrinogen fluorescence parameters in temperature range of 20-80 degrees C at different pH of the solution. It was found that the temperature increase from 20 to 40 degrees C for solutions with pH of 4,5-9,3 were not accompanied by the conformational changes of fibrinogen macromolecules. In the temperature range of 40-50 degrees C for neutral solutions conformational reconstruction of fibrinogen of undenatured character took place. Temperature increase above 50-55 degrees C brings about significant structural changes of fibrinogen molecule which are of denaturation nature.

Fibrinogen↗

PubMedDate not supplied

[Acidosis inhibits oxidative phosphorylation in intrasynaptosomal mitochondria by releasing calcium from cytoplasmic store].

The origin of calcium responsible for earlier observed acidosis-induced decrease in ATP content and inhibition of respiration in rat brain synaptosomes was studied. Acidosis (pH 6.0) inhibits both basal and potassium-stimulated 45Ca2+ uptake (60 mM KCl). Calcium channel blockers verapamil (100 microM) and 45Ca2+ (100 microM) have no effect on the level of ATP and respiration rate at pH 6.0. Theophylline (10 mM) releasing calcium from intracellular stores lowered ATP and O2 consumption rate at pH 7.4 but not at pH 6.0 being effective only in calcium-containing medium. Inhibitor of calcium transport in mitochondria ruthenium red (10 microM) prevented acidosis-induced ATP decrease. It is suggested that acidosis inhibits oxidative phosphorylation by releasing calcium from cytoplasmic stores with its subsequent transport into intrasynaptosomal mitochondria.

Acidosis↗