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Biomedical subjects

Kh S Khamitov

Publications and source records attributed to Kh S Khamitov.

At least 19 recordsLinked to original sources
PubMed1991

[Neurotrophic control of the ionic regulation mechanisms for intracellular water content in muscle fibers of mammals].

The volume change of the muscle fibres in the hypertonic medium begins with cell shrinkage. Later the cell volume increases up to the normal level because of the furosemide-sensitive CL(-)-influx activation. The property of the Cl(-)-influx to be activated in the hypertonic medium is abolished after denervation. That causes a loss of the ability of muscle fibres to restore their cell volume in the hypertonic medium.

Animals↗
PubMed1989

[Activation of the fast calcium input in the denervated smooth muscle of the cat nictitating membrane].

The excitation and contraction features of innervated and sympathetically denervated smooth muscle strips from cat's nictitating membrane have been studied by single sucrose gap arrangement. Increasing of smooth muscle cells sensitivity to drugs were accompanied by elevation of membrane response and the ability to generation of action potentials. Action potentials have been induced by agonists or high potassium concentration in external solution and spontaneously. In innervated muscle action potentials have been evoked as a result of depolarization by high potassium concentration of TEA blockade of potassium conductance. Induced and spontaneously generated action potentials were blocked by organic and inorganic antagonists of potential dependent Ca++ channels. In Ca-free solution action potentials were absent but might be supported by Ba++. Decrease of Na+ had no effect on smooth muscle excitability. It is supposed that activation of potential depended Ca++ channels in smooth muscle cells with pharmaco-mechanical coupling are under influence of sympathetic nerves.

Action Potentials↗
PubMed1989

[Regulation of the postsynaptic alpha-1-adrenoreceptors of the smooth muscle of the nictitating membrane in the cat].

Radioassay binding of the smooth muscle of the nictitating membrane of cat has revealed the specific binding sites of [3H]prazosin corresponding to alpha-1 adrenoceptors. There was a significant increase in the number of alpha-1 adrenoceptors without any changes in their affinity. Incubation of the culture of the preliminary sympathectomized smooth muscle with noradrenaline decreased the number of alpha-1 adrenoceptors also without altering the affinity of binding. So, it is concluded that sympathetic nervous system regulated the number of postsynaptic alpha-1 adrenoceptors by means of neurotransmitter (noradrenaline).

Animals↗
PubMed1989

[Effects of hyperosmolarity and furosemide on resting membrane potentials and skeletal muscle fiber volume in rats].

The changes of the muscle fibres volume and resting membrane potential (RMP) were studied following treatment with hypertonic medium and furosemide. The volume changes in hypertonic medium began with cell shrinkage and later have been followed by the volume increase up to normal level during 30-40 minutes. At the same time the medium hypertonicity caused muscle fibres depolarisation. The hypertonic-induced decrease of the RMP was delayed in the furosemide-treated muscle. Besides, furosemide abolished the muscle fibres volume restorative properties in hypertonic medium. It is suggested that the membrane depolarisation and cell volume restoration in hypertonic medium are the resultant effects of intracellular chloride ions level elevation which, in turn, have been evoked by activation of furosemide-sensitive Cl(-)-influx system.

Animals↗
PubMed1988

[Contractile function of the anterior tibial muscle of man at different stages of the denervation-reinnervation process].

The contractile and electromyographic properties of the tibialis anterior muscle from the affected and normal side have been studied in 27 patients with lumbar radiculopathies. It was found, that at the early stages of denervation-reinnervation process (according B. M. Gecht e.a.) the rise of the strength and rate characteristics twitch contraction are determined. At the late stages this process having electromyographic signs of 'largeness' of the motor units showed the 'smallness' of the same characteristics.

Electromyography↗
PubMed1988

[The alpha-adrenergic sensitivity of smooth muscle following sympathectomy].

The effect of sympathetic nerve stimulation on postsynaptic alpha-adrenoceptors of cat's smooth muscle nictitating membrane was studied. L-noradrenaline, adrenaline, phenylephrine and clonidine caused a concentration-dependent contraction. In denervated tissue, the concentration-response curve for clonidine mainly shifted to the left in comparison with the control; in contrast to the innervated smooth muscle, there were no reliable differences between the constant dissociation Ka and KB for alpha 1- and alpha 2-selective and nonselective adrenomimetics and adrenoblockaders. The data obtained suggest alteration of pharmacological characteristics of smooth muscle alpha-adrenoceptors after interruption of the sympathetic nerve.

Adrenergic alpha-Agonists↗
PubMed1988

[Restoration of muscle contractile properties after partial and complete denervation].

The subject of this experimental study was the isometric contractile properties of rat tibialis anterior muscle, number and average size of the motor units as well as type content and type-grouping of muscle fibres according to SDH activity in the same muscle after total and partial denervation (crushing the sciatic nerve and L4). It has been shown that in the process of reinnervation after total and partial denervation, quantitative differences with the general tendency in the dynamics of restoration of contractile properties of the whole muscle are found at different dynamics of restoration of electromyographic and muscle histochemical characteristics of motor units.

Animals↗
PubMed1988

[The electrical and contractile activity of denervated smooth muscle].

The effect of norepinephrine, histamine, serotonin and potassium chloride on electrogenesis and contraction was studied on innervated and denervated smooth muscles of cat's nictitating membrane. Denervated smooth muscles generate slow depolarizing potentials with the APs corresponding to tonic and phasic contractions, resp. Tonic contractions occur with no considerable change fo the MP in innervated muscles, phasic contractions being absent. Spontaneous generation of the APs is only possible in denervated muscles. Pharmacomechanical type of coupling between excitation and contraction seems to be characteristic of innervated smooth muscles, whereas electromechanical type is characteristic of denervated muscles. The denervation seems to result not only in the change of cells' sensitivity to transmitters but in the abnormality of coupling processes between excitation and contraction as well.

Animals↗
PubMed1988

[Comparison of the action of hyperpolarization and ethanol on frog end-plate currents at different cholinoceptor densities].

Both hyperpolarization of the postsynaptic membrane and ethanol delayed the decay rate of end-plate currents (EPC) in voltage clamp experiments of frog neuromuscular junctions. After a decrease of the acetylcholine receptors' density by alpha-bungarotoxin, the effect of ethanol, but not that of hyperpolarization, became less pronounced. It is concluded that there are differences between hyperpolarization and ethanol action on the processes controlling the EPC decay rate.

Animals↗
PubMed1988

[Iatrogenic diseases and scientific and technical progress].

Evolution of the term "iatrogenesis" and a widening range of the diseases varying in origin and clinical appearance covered with this term are considered. It is emphasized that such interpretation misrepresents the primary meaning aimed at orientation of the physicians to evaluation of the patient and doctor personality in view of its role in the genesis of psychic and somatic disturbances which tends to loom large with further scientific and technological progress. Iatrogenesis is supposed to be relevant to pathomorphosis of the borderline psychic conditions, prenosologic diagnosis and screening of population, drug addiction and alcoholism management. There is a tendency to further introduction of technical aspects into medical education.

Humans↗
PubMed1987

[Effect of disruption of chloride conductance on the development of denervation changes in muscle fiber membranes of the rat].

A decrease in resting MP, increase in the input resistance, appearance of anode breakdown APs, and extrajunctional acetylcholine sensitivity following denervation were revealed in the rat diaphragm muscle fibres. Addition of 1 X 10(-4) M furosemide to the culture medium reduced the degree of post-denervation muscle membrane depolarization and of extrajunctional acetylcholine sensitivity, but did not prevent the changes in passive electrical properties and in firing level of the muscle fibre membrane. Chloride ions could serve as intracellular messengers responsible for the neurotrophic control of muscle membrane resting potential and membrane sensitivity to acetylcholine. The Cl- are not essential in neurotrophic regulation of the electrogenic properties of membrane.

Acetylcholine↗
PubMed1987

[Importance of calcium ions and impulse activity for neurotrophic control of the membrane potential of muscle fibers in the rat].

The blockade of the Ca++ influx increased the postdenervation depolarization of the membrane potential in rat diaphragm muscle fibres, while elevation of the intracellular Ca++ content by caffeine hyperpolarized the muscle membrane. Direct electrical stimulation of muscle or application of carbamylcholine reduced the degree of postdenervation membrane depolarization. Verapamil and d-tubocurarine abolished the hyperpolarizing effect of the electrical stimulation. The hyperpolarizing effects of carbamylcholine and electrical stimulation were not added. It is suggested that the influx of the extracellular Ca++ through acetylcholine-sensitive ionic channels in the external muscle membrane contributes to the neurotrophic regulation of the membrane potential in rat muscle fibres.

Animals↗
PubMed1987

[Calcium and calcium-activated potassium currents of motor nerve endings in the frog].

Evoked electrical responses of nerve endings were recorded in experiments on frog cutaneous-pectoris muscle under visual control. During superfusion by Ca2+-free solution with tubocurarine a late inward current was found in the evoked response of nerve endings recorded by CaCl2 filled electrode. With addition of the external solution of 4-aminopyridine the late current was changed into an outward one. This outward current depended on Ca2+ concentration in the electrode, decreased after local increase of K+ concentration and was abolished by Co2+ ions. Local ionophoretic application of tetraethyl-ammonium eliminated the outward current and revealed a strong and prolonged inward current. Similar currents were recorded by microelectrodes filled with SrCl2, BaCl2 and MgCl2. It is concluded that the late inward current is carried through potential-dependent calcium channels, while the late outward one--through Ca2+-activated K+ channels. The ratio of calcium and Ca2+-activated potassium currents in motor nerve endings and their role in the transmitter release are discussed.

Animals↗
PubMed1987

[Role of opioid peptides in the neurotrophic control of the acetylcholine-sensitive membrane of rat skeletal muscle fibers].

The influence of opiate peptides on the development of hypersensitivity to acetylcholine has been revealed in muscle fibers membrane after denervation of rat diaphragm muscle. The addition of 1 X 10(-8) M beta-endorphin or dalargin to the culture medium prevented the appearance of extra-junctional acetylcholine sensitivity. The peptide containing only three amino acids and identical to the initial dalargin region did not possess the same effect. Moreover, if this peptide was present in the culture medium in the concentration higher than that of dalargin, the effect of dalargin was blocked. It is suggested that the neurotrophic regulation of acetylcholine-sensitive membrane properties of skeletal muscle fibers is accomplished with opiate neurogenic peptide, e.g. beta-endorphin.

Acetylcholine↗
PubMed1987

[Effect of beta-endorphin on the development of denervation changes in the membrane of the muscle fiber in the rat].

A decrease in the resting membrane potential, an increase in the input resistance, appearance of the anode breakdown and tetrodotoxin-resistant action potentials and extrajunctional acetylcholine sensitivity following denervation were revealed in surviving rat diaphragm muscle fibres. Addition of beta-endorphin (1.10(-8) M) to the culture medium prevented on increase in the input resistance and reduced a degree of the extrajunctional acetylcholine sensitivity, but did not inhibit the appearance of the anode breakdown and tetrodotoxin-resistant action potentials. Naloxone (1.25.10(-6) M) did not avert the effect of beta-endorphin, more over it exerted a beta-endorphin-like effect on the denervated muscle fibres. It is suggested that beta-endorphin can be the factor which is responsible for the neurotrophic control of passive electrical properties of the muscle fibre membrane and neurotrophic regulation of the membrane sensitivity to acetylcholine.

Acetylcholine↗
PubMed1987

[Effect of acetylcholine and carbamylcholine on the resting membrane potential of denervated muscle in the rat].

The decrease of resting MP after denervation in diaphragm muscle of the rat was studied in vitro. Transitory activation of Na+,K+-pump by carbamylcholine, acetylcholine or adrenaline hyperpolarized the muscle fiber membrane but did not compensate the postdenervation fall of the MP. Similarly, the permanent presence of carbamylcholine at culturing media did not prevent the development of changes in the MP after denervation. The decrease of MP was accompanied by spontaneous release of acetylcholine for 24 hrs. Synaptic acetylcholine seems to play no obvious role in neurotrophic control of the resting MP.

Acetylcholine↗
PubMed1987

[Simulation of the neurotrophic control of the resting membrane potential in rat skeletal muscle by using electrical stimulation and an exogenous cholinomimetic].

Decrease of the resting MP caused by denervation of the rat diaphragm muscle, was studied in vitro. Addition of carbamylcholine as well as electrical stimulation hyperpolarized the muscle membrane, the effect of the former being not prevented by d-tubocurarine. The hyperpolarizing effects of carbamylcholine and electrical stimulation used simultaneously were not added up. The resting MP in muscles with long stump of the nerve was not affected by d-tubocurarine added to the culturing medium. The action of synaptic acetylcholine via d-tubocurarine-insensitive mechanism and the nerve impulsation seem to serve as additional factors in complete actualization of the resting MP neurotrophic control.

Animals↗