Bradykinin and muscle stretch alter contralateral cat neck muscle spindle output.
The objective of this study was to investigate the activity of primary and secondary muscle spindle afferents (MSAs) in neck muscles, when the contralateral splenius or trapezius muscles were (1) exposed to i.m. injection of bradykinin (BK) (6-86 microg/ml), (2) stretched, (3) stretched during exposure to BK or (4) stretched after exposure to BK. It was found that injection of BK, muscle stretch and the combination of the two stimuli significantly excited primary and secondary MSAs via reflex effects onto static fusimotor neurones. BK, alone, and in combination with muscle stretch, induced more frequent, potent and long lasting effects as compared to muscle stretch. The effects of muscle stretch was significantly increased after exposure of BK, indicating that stretch-sensitive nerve-endings within neck muscles are sensitised by BK. The results are discussed in relation to the disturbances in motor co-ordination and proprioception found in patients suffering from chronic muscle pain in the cervical region.
Wenngren
B I
BI
Department of Musculoskeletal Research, National Institute for Working Life, Umeå, Sweden.
Pedersen
J
J
Sjölander
P
P
Bergenheim
M
M
Johansson
H
H
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002415:Cats; D004558:Electric Stimulation; D009470:Muscle Spindles / Q000187:drug effects / Q000502:physiology*; D009334:Neck Muscles / Q000187:drug effects* / Q000294:innervation / Q000502:physiology*; D009431:Neural Conduction / Q000187:drug effects; D013997:Time Factors
D001920:Bradykinin