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Titolo:
Stimulation of chemosensitive afferents from multifidus muscle does not sensitize multifidus muscle spindles to vertebral loads in the lumbar spine of the cat
Autore:
Kang, YM; Wheeler, JD; Pickar, JG;
Indirizzi:
Palmer Ctr Chiropract Res, Davenport, IA 52803 USA Palmer Ctr Chiropract Res Davenport IA USA 52803 Davenport, IA 52803 USA Univ Iowa, Dept Biomed Engn, Iowa City, IA 52242 USA Univ Iowa Iowa City IA USA 52242 ept Biomed Engn, Iowa City, IA 52242 USA Univ Iowa, Iowa Spine Res Ctr, Iowa City, IA 52242 USA Univ Iowa Iowa City IA USA 52242 a Spine Res Ctr, Iowa City, IA 52242 USA Kansas State Univ, Coll Vet Med, Dept Anat & Physiol, Manhattan, KS 66506 USA Kansas State Univ Manhattan KS USA 66506 Physiol, Manhattan, KS 66506 USA
Titolo Testata:
SPINE
fascicolo: 14, volume: 26, anno: 2001,
pagine: 1528 - 1536
SICI:
0362-2436(20010715)26:14<1528:SOCAFM>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
FUSIMOTOR NEURONS; SKELETAL-MUSCLE; GROUP-III; GAMMA-MOTONEURONES; DECEREBRATE CATS; DISCHARGE RATE; NECK MUSCLES; PAIN; BRADYKININ; REFLEX;
Keywords:
lumbar vertebra; multifidus; muscle spindle afferents; bradykinin; gamma-motoneuron; pain-spasm-pain cycle;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Pickar, JG Palmer Ctr Chiropract Res, 741 Brady St, Davenport, IA 52803 USA Palmer Ctr Chiropract Res 741 Brady St Davenport IA USA 52803 A
Citazione:
Y.M. Kang et al., "Stimulation of chemosensitive afferents from multifidus muscle does not sensitize multifidus muscle spindles to vertebral loads in the lumbar spine of the cat", SPINE, 26(14), 2001, pp. 1528-1536

Abstract

Study Design. Electrophysiologic recordings from muscle spindle efferents innervating the lumbar multifidus muscle of the cat white loading the L6 vertebra at its spinous process and while exposing the segmentally adjacent lumbar multifidus muscles to algesic and inflammatory mediators. Objectives. The purpose of this study was to investigate a possible mechanism underlying muscle spasm and pain in the lumbar spine. The hypothesis was tested that stimulation of chemosensitive afferents with receptive endings in the paraspinal muscle increases the discharge of paraspinal muscle spindle afferents during loading of a lumbar vertebra. The presence of such a phenomenon would provide a mechanism by which pain or inflammation could alter segmental lumbar biomechanics and contribute to lumbar spine dysfunction. Summary of Background Data. Muscle pain, tenderness, and altered muscle tone are often associated with musculoskeletal disorders. The literature suggests that stimulation of Group III and IV muscle afferents sensitive to algesic or inflammatory metabolites increases the stretch sensitivity of muscle spindles via a reflex pathway involving gamma -motoneurons. The reflex increase in muscle spindle activity, in turn, reflexly increases the excitability of alpha -motoneurons leading to enhanced muscle tone and the further accumulation of muscle metabolites and subsequent pain, Studies in the cervical spine support this hypothesis. It has not been investigated in the lumbar spine. Methods. Single unit activity from muscle spindles in the L6 multifidus muscle were recorded from the cut peripheral end of the L6 dorsal root in alpha -chloralose-anesthetized cats and in decerebrate unanesthetized cats. The L6 vertebra was loaded at its spinous process using a force-feedback motor. Ramp and hold loads were delivered at 25%, 50%, 75%, and 100% body weight. Chemosensitive afferents in the L5 and L7 multifidus muscle were stimulated by bathing (subfascial injection) or infiltrating (intramuscular injection) the L5 and L7 multifidus muscles with bradykinin or capsaicin. Results, Loading the L6 vertebra stimulated muscle spindles in the: L6 multifidus muscle. Neither the saline volume control nor bradykinin nor capsaicin injected subfascially or intramuscularly affected the response of L6 multifidus muscle spindles to ramp and hold vertebral loads in the alpha -chloralose-anesthetized cat. In addition, neither saline nor bradykinin nor capsaicin injected intramuscularly affected the activity of L6 multifidus muscle spindles to ramp and hold vertebral loads in the unanesthetized decerebrate cat. Conclusions. These results indicate that stimulation of small diameter muscle afferents in a deep-muscle of the lumbar spine does not sensitize muscle spindles to vertebral loads. These data do not support the hypothesis that fusimotor reflexes evoked by chemosensitive muscle, afferents contribute to muscle spasm or to changes in muscle tone in the lumbar spine. In addition, the present results do not provide evidence for the pain-spasm-pain cycle in the lumbar spine.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/09/20 alle ore 12:00:11