[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.

[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.

[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.

[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.

[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.

[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.

[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 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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[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.

[Effect of thyroxine on skeletal muscles in hereditary myodystrophia].

The influence of 3-week L-thyroxin administration on contractility and histochemical composition of skeletal muscles was studied in 129Rj mice of normal and dystrophic genotypes. The rise in speed characteristics of isometric contraction and percentage of type II "fast" fibers was established in both types of animals. Contractile properties in dystrophic animals, receiving L-thyroxin, showed a tendency towards normalization and were comparable to those of normal animals.

[Contractile characteristics of developing fast and slow muscles during colchicine blockade of axoplasmic transport in their nerves].

Within a month after colchicine application to the sciatic nerve of a newborn rat, deviation from the normal development occurred in contractile and histochemical properties of fast (extensor digitorum longus) and slow (soleus) muscles. The data obtained revealed the importance of neurogenic agents of neurotropic control transported from pericarions of motoneurons for differentiating skeletal muscle fibers.

[Contractile properties of reinnervated skeletal muscle and their relation to the degree of nerve damage].

Experiments with 22 rats have shown that the anterior tibial muscle in the stage of incomplete reinnervation is marked by decreased force and retardation of the semi-relaxation of an isometric contraction. In completely reinnervated muscles, the changes in the contractility are determined by the degree of nerve damage. The group of animals with the sciatic nerve injury demonstrated the contractility characteristic of a slower muscle, in contrast to the group with the fibular nerve damage.

[Lactate dehydrogenase isoenzyme spectrum of fast and slow muscles with innervation disorders].

A relative content of muscle fibers of various types and the spectrum of lactate dehydrogenase (LDH) isozymes were studied in fast-twitch (extensor digitorum longus) and slow-twitch (soleus) muscles of newborn rats, of those aged 2, 3 weeks and one month and of adult rats after neonatal sciatic denervation and application of 0.5 mM colchicine solution to the sciatic nerve. No muscle fibers of various types were found (from the level of succinate dehydrogenase activity) in one-month-old rats, whereas the control and fast-twitch muscles showed A, B and C types and the slow-twitch one B and C types.