Sympathetic control of skeletal muscle function: possible co-operation between noradrenaline and neuropeptide Y in rabbit jaw muscles.
Stimulation of the cervical sympathetic nerve at 10/s increases by 12.9 +/- 0.7% peak tension of maximal twitches in the directly stimulated jaw muscles and markedly depresses (41.6 +/- 1.3%) the tonic vibration reflex (TVR) elicited in the same muscles by vibration of the mandible. Both effects are not significantly influenced by administration of beta-adrenoceptor antagonists. When both alpha- and beta-adrenergic receptors are blocked, sympathetic stimulation induces a very small increase in twitch tension (3.8 +/- 0.7%), while no detectable change in the TVR is observed. Close arterial injection of alpha 1-adrenoceptor agonist phenylephrine mimics the effects induced by sympathetic stimulation on twitch tension and TVR, dose-dependently. The noradrenaline co-transmitter neuropeptide Y also produces a long-lasting, dose-dependent increase in the twitch tension which is unaffected by blockade of adrenergic receptors as well as of the neuromuscular junctions. Contribution of neuropeptide Y to the sympathetically-induced reduction of the stretch reflex is not clearly demonstrated. These data suggest that co-operation between noradrenaline and neuropeptide Y may be effective in determining sympathetic modulation of skeletal muscle function.
Grassi
C
C
Institute of Human Physiology, Catholic University, S. Cuore, Rome, Italy.
Deriu
F
F
Roatta
S
S
Santarelli
R
R
Azzena
G B
GB
Passatore
M
M
D000818:Animals; D004305:Dose-Response Relationship, Drug; D007568:Jaw / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009478:Neuropeptide Y / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D010656:Phenylephrine / Q000494:pharmacology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000502:physiology*
D009478:Neuropeptide Y; D010656:Phenylephrine; D009638:Norepinephrine