title: Effects of endogenous nitric oxide in activation of group IV muscle afferents.
abstract: Based on previous observations that acute hypoxemia, which enhances nitric oxide (NO) production, depresses the activation of group IV afferents after repetitive low-frequency muscle stimulation (MS), we hypothesized that endogenous NO modulates the response of these nerve endings to their specific stimuli. The present study in rabbits examined the effects of a blocker of NO synthase (NG-nitro-L-arginine methyl ester L, L-NAME) and an exogenous NO donor (3-morpholinosydnonimine, SIN-1) on the group IV afferents of tibialis anterior. The efficacy of the two test agents was judged by their effects on systemic blood pressure. L-NAME markedly elevated (+46%) the resting discharge rate of group IV afferents but abolished their activation after repetitive MS. After SIN-1 injection, there was a transient decrease in blood pressure, which correlated well with a lowered resting discharge rate of group IV afferents. SIN-1 infusion caused a stable reduction of blood pressure; the resting afferent nerve discharge rate began first to decrease but then recovered control mean values. SIN-1 infusion abolished the activation of group IV afferents after MS. This study indicates that endogenous NO production in a resting or contracting muscle attenuates the baseline activity of group IV muscle afferents and their activation after repetitive muscle contractions.
authors.affiliation: Laboratoire de Physiopathologie Respiratoire (UPRES EA 2201), Faculté de Médecine, Boulevard Pierre Dramard, 13916 Marseille, France.
authors.forename: S
authors.initials: S
authors.lastname: Arbogast
authors.forename: J L
authors.initials: JL
authors.lastname: Darques
authors.forename: F
authors.initials: F
authors.lastname: Bregeon
authors.forename: Y
authors.initials: Y
authors.lastname: Jammes
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000294:innervation*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009475:Neurons, Afferent / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D011817:Rabbits
chemical_list: D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D019331:NG-Nitroarginine Methyl Ester