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B A Tashmukhamedov

Publications and source records attributed to B A Tashmukhamedov.

At least 19 recordsLinked to original sources
PubMed2003

Osmotic water permeability and regulatory volume decrease of rat thymocytes.

Rat thymocytes displayed robust regulatory volume decrease (RVD) when suspended in NaCl-based hypotonic Ringer solutions. The RVD of thymocytes was completely abolished upon replacement of external Na+ ions with K+, indicating a role of coupled efflux of K+ and Cl- ions as a driving force of regulatory volume decrease. Osmotic water permeability (Pf) measured in KCl-based hypotonic solutions was (1.3 +/- 1.0 x 10(-4) cm/s at 25 degrees C and was temperature-dependent with low activation energy (Ea = 4.65 +/- 0.77 kcal/mol) characteristic to water transport through pores. HgCl2 and a sulfhydryl-blocking reagent, methyl methanethiosulphonate (MMTS), modulated the water permeability of thymocytes in a biphasic manner: inhibited at low dose (0.1-1 micromol/l) and restored or even enhanced at higher (10-100 micromol/l) concentrations. RVD paralleled the Pf: it was greatly suppressed at low dose of MMTS (sufficient to attenuate the water transport), but recovered at higher dose, when the water movement was restored. Therefore we suggest that thymocytes require the effective water transport for functional regulatory volume decrease.

Animals↗
PubMed1999

Channel properties of the purified glutamate receptor from rat brain reconstituted in planar lipid bilayer membrane.

The properties of the purified rat brain glutamate receptor (GluR), reconstituted in planar lipid bilayer (BLM) were characterised. The single channel currents activated by glutamate and aspartate were similar. The different kinetics of current fluctuation were observed. Paroxysms of channel activity seems to be resulted from the transit of GluR through its active conformation from which it can open several times before desensitising. The effect of concanovaline A (Con A) as an agent blocking desensitisation of glutamatergic synapses was investigated. It was shown that Con A evokes high levels of conductivity and prolonged opening events of channels. Another agent, which stabilises glutamate activated conductivity, dithiothreitol (DTT), evokes "chronic" channel activity. This study demonstrates that purified GluR reconstituted in planar lipid bilayers exhibits the ion-conductivity properties that are associated with the postsynaptic membrane.

Animals↗
PubMed1997

Ionophoretic properties of ferutinin.

The influence of the natural terpenoid ferutinin (4-oxy-6-(4-oxybenzoyloxy) dauc-8,9-en), isolated from the plant Ferula tenuisecta, on ion permeability of biological and artificial membranes was investigated. It was shown that ferutinin, in the concentration range 1-50 microM, increases the permeability of thymocytes, mitochondria, sarcoplasmic reticulum, liposomes and bilayer lipid membranes (BLM) for Ca2+. Ferutinin establishes a transmembrane potential in BLM equal to the Nernst's potential. The permeability ratio for Na+/Ca2+ is 0.41. The dependence of BLM conductivity on ferutinin concentration is linear. The stoichiometry of the ferutinin:Ca2+ complex is 2, assuming the formation of a structure with participation of two terpenoid molecules and one Ca2+ ion.

Animals↗
PubMed1989

[Argiopinin-binding proteins from the membrane of the bull cerebral cortex].

The 40 kDa argiopinin-binding glycoprotein has been isolated from the solubilised preparations of bovine cerebrum membranes by means of two-step biospecific chromatography on affinity sorbents with immobilized glutamate and argiopinins. This receptor component displays a specific L-[3H]glutamate binding with Kd = 0.18 +/- +/- 0.019 mumole and Bmax = 43 +/- 4.5 nmole/mg. Amino acid analysis reveals it to be a member of integral membrane proteins.

Amino Acids↗
PubMed1988

The structure of Staphylococcus aureus alpha-toxin-induced ionic channel.

Polyethylene glycols (PEG) with molecular weight less than or equal to 3000 were shown to effectively protect human erythrocytes from osmotic lysis induced by alpha-staphylotoxin (ST). PEG with MW less than 3000 do not change the conductivity of ion channels induced by ST in bilayer lipid membranes (BLM). Changing the bilayer from a pure phosphatidylcholine (PC) to a negatively charged phosphatidylserine (PS) film results in an asymmetry of the current-voltage characteristics. This is evidenced by the asymmetrical position of the ST-channel pore in bilayer membranes. The results obtained allow to conclude that the ST-channel is an interprotein pore filled with water (with an inner diameter of 2.5-3 nm and a length of approximately 10 nm). It is composed of six molecules of alpha-toxin from Staphylococcus aureus. The ST-channel incorporates into a membrane with only one mouth in contact with the polar lipid heads and the other one protruding 4.5-5 nm from the bilayer plane in water solution.

Bacterial Toxins↗
PubMed1985

Postsynaptic blocking of glutamatergic and cholinergic synapses as a common property of Araneidae spider venoms.

Venom effects of eight Araneidae spider species were studied using locust and frog neuromuscular junctions. The spider venoms irreversibly blocked miniature excitatory postsynaptic potentials and excitatory postsynaptic potentials of locust neuromuscular junction. The frog miniature end-plate potentials and end-plate potentials were also blocked, but they recovered upon washing of the preparation with physiological solution.

Animals↗
PubMed1985

The channel-forming component of the Theridiidae spider venom neurotoxins.

It is known that Steatoda (Lityphantes) paykulliana and Latrodectus mactans tredecimguttatus spider venoms are toxic to mammals and insects. These venoms act presynaptically eliciting massive release of transmitters. They also form channels in bilayer lipid membranes (BLM) that are selective for cations. Venoms of both spider species were fractionated by gel filtration on a Sephadex G-100 column. The fraction obtained were tested on neuromuscular preparations of frog and locust and on BLM. A fraction of low molecular weight components (about 5000 daltons and less) was disclosed. This fraction showed presynaptic and channel-forming effects similar to those of crude venoms and of high molecular weight toxin fractions, obtained simultaneously from these venoms. It was shown that channels formed in BLM by crude venoms and its different fractions are identical. Also, it was found that the low molecular weight channel-forming component is a construction element of high molecular weight toxins. On the basis of data obtained a toxin structure model of the Theridiidae family spider venoms was proposed.

Animals↗
PubMed1985

[Channel-forming action--a general property of venoms of spiders in the family Theridiidae (Aranei)].

The study of venom action of 10 spider species of Theridiidae family has shown that they cause the formation of the cation selective channels on the bilayer lipid membranes. This action does not depend on the species sex and age and it is the important diagnostic characteristic of the family. The channel-forming effect is due to the presence of the peptide with molecular weight about 5000 daltons in venoms of Theridiidae spider family.

Animals↗
PubMed1985

Reconstitution in bilayer lipid membranes of the crab Potamon transcaspicum spider venom sensitive glutamate receptors.

Membrane proteins have been isolated from neuromuscular synapses of the crab Potamon transcaspicum using a specific blocker of glutamatergic synapses, the neurotoxin of the spider Argiope lobata. These membrane components have been shown to induce glutamate-sensitive conductance in bilayer lipid membranes (BLM) in the presence of sodium ions. As an agent blocking desensitization of glutamatergic synapses, concanavalin A was shown to enhance the conductance and to abolish desensitization. Diethylester of glutamic acid as a blocker of glutamatergic synapses inhibited glutamate-induced conductance. No similar change in conductance was seen when BLM was modified by a membrane proteins -neurotoxin complex. Conductance current fluctuations induced by these receptor protein components were monitored by the single-channel registration method.

Animals↗