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M Falempin

Publications and source records attributed to M Falempin.

47 records · Page 3Linked to original sources
PubMed1983

Reinnervation of skeletal muscles by vagal sensory fibres in the sheep, cat and rabbit.

Fibres of the sterno-cleido-mastoid (s.c.m.) muscle normally innervated by the accessory nerve have been reinnervated by afferent fibres of the vagus nerve after supranodose vagal-accessory nerve anastomoses or direct implantation of the vagus nerve into the s.c.m. in cats, rabbits and sheep. The afferent fibres contributing to this reinnervation were confirmed to be cholinergic as transmission was blocked by gallamine, and histochemical evidence obtained of cholinergic motor end-plates. The association of the axons of cells of the nodose ganglion and s.c.m. muscle fibres was further demonstrated when horseradish peroxidase injected into the s.c.m. was detected in somata of nodose ganglia cells. The largest number of reinnervated motor units, fifty, identified by electromyographic recording from the s.c.m. muscle, represents a small proportion of the afferent fibres in the vagus. Factors contributing to this degree of reinnervation are discussed. Conduction velocities in afferent fibres involved in the reinnervation were in the range less than 2.5 to greater than 35 m/s with 36% being 6-12 m/s. Between 40 and 98.5% of the myelinated fibres of the accessory nerve replaced by vagal afferent fibres were less than 6 microns in diameter. The afferent nerve fibres involved in the reinnervation were associated with larynx, respiratory tract, oesophagus and stomach. Afferent discharges recorded as bursts of electromyographic potentials in the s.c.m. occurred during spontaneous movements of these structures and on their mechanical stimulation.

Accessory Nerve↗
PubMedDate not supplied

Reinnervation of a striated muscle by vagal sensory axons.

Fibres of the sterno-cleido-mastoid (s.c.m.) muscle normally innervated by effects of the accessory nerve have been reinnervated by afferent fibres of the vagus nerve after supranodose vagal-accessory nerve anastomoses or direct implantation of the vagus nerve into the s.c.m. in 58% of the rabbits, 60% of the cats and 75% of sheep in which experiments were performed. Afferents of the vagus growing from cell bodies of the nodose ganglion after severance of central connections can replace the efferent of motor supply to the muscle. Evidence that there was reinnervation of the s.c.m. muscle by vagal afferent fibres was provided from the observations that: (i) electrical stimulations of the anastomosed cervical vagus nerve elicited potentials in the s.c.m. muscle which were abolished by local anaesthesia or final section of the nerve proximal to the site of stimulation; (ii) discharges recorded as bursts of electromyographic potentials occurred during spontaneous movements of larynx, respiratory tract, oesophagus and stomach and on their mechanical or evoked stimulation; and (iii) horseradish peroxidase injected into the reinnervated s.c.m. muscle was detected in somata of ipsilateral nodose ganglia cells. The afferent fibres contributing to the reinnervation were confirmed to be cholinergic as transmission was blocked by gallamine and histochemical evidence obtained of cholinergic motor end-plates. Factors which may have limited the small extent of reinnervation--only one vagal sensory axon out of 600 is able to form functional connections--are discussed.

Animals↗
PubMedDate not supplied

Muscle atrophy associated with microgravity in rat: basic data for countermeasures.

Morphological, contractile properties and myosin heavy chain (MHC) composition of rat soleus muscles were studied after 2 weeks of unloading (HS) and after 2 weeks of HS associated with selective deafferentation (HS + DEAF) at the level L4 and L5. The same significant reductions in muscle mass and tetanic tension were found after HS and HS + DEAF. However, the transformation of the slow-twitch soleus muscle towards a faster type characterized by a decrease in twitch time parameters and an increase in fast-twitch type MHC isoforms in HS did not appear in HS + DEAF conditions. Our results also showed that a pattern similar to firing rate of motoneurones innervating slow-twitch muscles inhibited the slow to fast fiber changes observed during HS. Nevertheless, neither the loss of mass or force output in the HS muscles were prevented by electrostimulation. Immobilization in a stretched position during HS maintained the muscle wet weight, mechanical and electrophoretical characteristics close to control values. We concluded that the decrease in mechanical strains imposed on the muscle during unloading was the main factor for the development of atrophy, while the kinetic changes might be predominantly modulated by the nervous command. These basic data suggested that some experimental conditions such as electrostimulation or stretching, could participate in countermeasure programmes.

Afferent Pathways↗