DENERVATION

From Big Medical Encyclopedia

DENERVATION (Latin the de-prefix extraction, destruction + nervus a nerve) — dissociation of bonds of any body or body tissue with a nervous system. The term «denervation» is more often applied in cases of dissociation of an efferent innervation, but can designate also disturbance of an afferent innervation (see. Deafferentation ).

In clinical practice of D. it is used as a method of treatment of neuritis and neuralgia (e.g., at not stopped epileptiform neuralgia), kauzalgiya, stump neuralgias, intestinal and acalculous bilious gripes, frustration of a trophicity (trophic ulcers of extremities) and peripheric circulation (an angioneurosis, a Raynaud's disease), etc. In fiziol, researches D. use for studying of dependence of any bodies on influence of a nervous system and for separate studying of nervous and humoral influences. Is one of the main methods of a research of evolution of functions. Use of this method, in particular, allowed L. A. Orbeli (1934) to formulate the provision on evolution of muscular tissue, according to Krom the muscle deprived of a motor innervation is returned to more primitive state similar to embryonal.

Is reached by section of all visible nervous branches, use of various chemical substances (nicotine, atropine, novocaine, alcohol, phenol, dekametony, tubocurarine, etc.), physical. the influences breaking carrying out excitement on nerve fibrils and in synapses (e.g., the holodovy block), use of immunological methods, etc.

In the researches conducted on unstriated and skeletal muscles, glands, heart, neurons vegetative gangliyev back and a brain of various animals it was revealed that through a nek-swarm time after D. bodies and fabrics gain hypersensitivity to effect of chemical substances and the arriving nervous impulses.

U. Kennon formulated the law of denervation (1935), later expanded Rozenblyutom and Garcia Ramos (A. S. Rosenblueth, J. Garsia Ramos, 1945). Under this law if one of links of a functional chain of neurons is interrupted, then the general or partial D. of the subsequent links in a chain leads to sensitization of all distal elements (including and denervated structures and effectors); sensitization is more in links which directly adjoin the cut neurons, and less in more remote elements. Such sensitization is caused by many mechanisms. So, after D. of muscle fibers emergence of holinoretseptor on all surface of fiber is noted; also changes in a relative positioning of holinoretseptor come to light. Is followed by deep biochemical, and structural changes of denervated body. Clinically D. can be shown in the form of various motive (paralyzes, contractures, hyperkinesias), trophic (trophic ulcers, dystrophy, change of sweating) and sensitive disturbances. One of the heaviest types of increase and a perversion of sensitivity are kauzalgiya and stump neuralgias.

G. N. Sorokhtin and it sotr. (researches in 1945 — 1973) it is shown that as a result of reversible or irreversible D. in various bodies and fabrics, such as a skeletal muscle, a sialaden, a sympathetic ganglion, a respiratory center and others, there is a special state (so-called deficit of excitement) connected with the termination of receipt of nervous impulses. It is characterized by development of a condition of passive hyperpolarization and depending on morfol, and functional features of structure of bodies and fabrics is followed by the increased or lowered excitability.


Bibliography: Kennon V. and Rozenblyut And. Sensitization of denervated structures, the Law of denervation, the lane with English, M., 1951; Michel assembly. I. izeymal E. V. Atsetilkholin, about the molecular mechanism of action, L., 1970, bibliogr.; Orbeli L. A. Chosen works, t. 1, page 59, M. — L., 1961; Sorokhtin G. N. Reaction of excitable systems to deficit of excitement, M., 1968; Physiology of touch systems, the p. 3, Physiology of mechanioreceptors, under the editorship of O. B. Ilyinsky, L, 1975.

V. V. Sherstnev.

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