Abstract
This study on the effects of capsaicin on primary afferents from normal knee joints of the cat was performed to further elucidate the mechanisms of articular pain evoked by an acute arthritis and by chemical irritants. It showed that close i.a. bolus injection of capsaicin (10−7–10−4 M) excites most fine articular afferents (conduction velocity ≤11.3 m/s) whereas fast units are not excited. Fine afferents with low to medium thresholds to knee joint movement are less readily excited by capsaicin than high threshold ones. The response to capsaicin is usually a rapid burst of impulses of a very short latency. This response pattern differs considerably from that seen after application of endogenous substances produced in inflammation. Thus capsaicin seems to differ in its mode of action from that of endogenous algesic substances.
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References
S. H. Buck and T. F. Burks,The neuropharmacology of capsaicin: review of some recent observations, Pharmacol. Rev.38, 179–226 (1986).
B. Heppelmann, H.-G. Schaible and R. F. Schmidt,Effects of prostaglandins E 1 and E 2 on the mechanosensitivity of group III afferents from normal and inflamed cat knee joints. InAdvances in Pain Research and Therapy (Eds. H. L. Fields, R. Dubner, R. Cervero) pp. 91–101, Raven, New York 1985.
M. K. Herbert and R. F. Schmidt,Activation of Group III and IV afferent units from normal and inflamed cat knee joints by histamine. Neuroscience Letters Suppl.26, S521 (1986).
M. K. Herbert and R. F. Schmidt,Effect of serotonin on groups III and IV afferent units from acutely inflamed cat knee joint. Pflügers Arch. Supp. 1408, R66 (1987).
R. Kanaka, H.-G. Schaible and R. F. Schmidt,Activation of fine articular afferent units by bradykinin. Brain Res.327, 81–90 (1985).
H.-G. Schaible and R. F. Schmidt,Activation of groups III and IV sensory units in medial articular nerve by local mechanical stimulation of knee joint. J. Neurophysiol.49, 35–44 (1983).
H.-G. Schaible and R. F. Schmidt,Responses of fine medial articular nerve afferents to passive movements of knee joint. J. Neurophysiol.49, 1118–1126 (1983).
H.-G. Schaible and R. F. Schmidt,Effects of an experimental arthritis on the sensory properties of fine articular afferent units. J. Neurophysiol.54, 1109–1122 (1985).
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He, X., Schmidt, R.F. & Schmittner, H. Effects of capsaicin on articular afferents of the cat's knee joint. Agents and Actions 25, 222–224 (1988). https://doi.org/10.1007/BF01965017
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DOI: https://doi.org/10.1007/BF01965017