title: Does metabosensitive afferent fibers activity differ from slow- and fast-twitch muscles?
abstract: This study was designed to investigate the metabosensitive afferent response evoked by electrically induced fatigue (EIF), lactic acid (LA) and potassium chloride (KCl) in three muscle types. We recorded the activity of groups III-IV afferents originating from soleus, gastrocnemius and tibialis anterior muscles. Our data showed a same pattern of response in the three muscles after chemical injections, i.e., a bell curve with maximal discharge rate at 1 mM for LA injections and a linear relationship between KCl concentrations and the afferent discharge rate. Furthermore, a stronger response was recorded after EIF in the gastrocnemius muscle compared to the two other muscles. The change in afferent discharge after 1 mM LA injection was higher for the gastrocnemius muscle compared to the response obtained with the corresponding concentration applied in the two other muscles, whereas changes to KCl injections did not dramatically differ between the three muscles. We conclude that anatomical (mass, phenotype, vascularization, receptor and afferent density…) and functional (flexor vs. extensor) differences between muscles could explain the amplitude of these responses.
authors.affiliation: Aix-Marseille Université (AMU) - Centre National de la Recherche Scientifique (CNRS), UMR 7287 «Institut des Sciences du Mouvement: Etienne-Jules MAREY» (ISM-EJM), Equipe «Plasticité des Systèmes Nerveux et Musculaire», Parc Scientifique et Technologique de Luminy, Faculté des Sciences du Sport de Marseille, CC910 - 163 Avenue de Luminy, 13288, Marseille Cedex 09, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Caron
authors.forename: Patrick
authors.initials: P
authors.lastname: Decherchi
authors.forename: Tanguy
authors.initials: T
authors.lastname: Marqueste
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000009:adverse effects; D019344:Lactic Acid / Q000009:adverse effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018763:Muscle Fatigue / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011189:Potassium Chloride / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019344:Lactic Acid; D011189:Potassium Chloride