Tension development in lumbrical muscles and concomitant increase of activity in Aα and Aβ afferents during sympathetic stimulation in the cat

C. Grassi, G. M. Filippi, M. Passatore

Research output: Contribution to journalArticle

Abstract

In anaesthetized and curarized cats electrical stimulation of the lumbar sympathetic trunk, at frequencies within the physiological range, induces the development of a small tension in superficial lumbrical muscles (50-100 mg in different preparations). This effect can be reproduced in anaesthetized and curarized cats by stimulating the peripheral stump of the tibial nerve with parameters adequate to activate the entire C-fibre group, and therefore postganglionic sympathetic fibers. The collision technique was used to evaluate in the tibial nerve possible changes in afferent activity from the skinned foot. It was found that an increase of non-cutaneous activity consistently occurs in Aβ and, occasionally, in Aα fibre groups. Secondary and primary spindle afferents, respectively, belong to these fibre groups. It was also found that: (1) the tension development in lumbrical muscles and the increase of the afferent activity of non-cutaneous origin exhibit similar time course; (2) the two events are affected in parallel by the same stimulus parameters; (3) both events are abolished by α-adrenoceptor antagonists. Therefore the possibility of a sympathetic fusimotor action affecting mainly secondary afferents is suggested and discussed.

Original languageEnglish
Pages (from-to)15-23
Number of pages9
JournalBrain Research
Volume435
Issue number1-2
DOIs
Publication statusPublished - Dec 1 1987

Keywords

  • Motor activity
  • Neuromuscular spindle
  • Sympathetic nervous system

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

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