Abstract |
High threshold voltage-dependent P- and Q-type calcium channels are involved in neurotransmitter release. In order to investigate the role of P- and Q-type calcium channels in the mechanosensory (nociceptive) processing in the spinal cord, their participation in the responses of spinal wide-dynamic-range neurons to innocuous and noxious mechanical stimulation of the knee and ankle joints was studied in 30 anaesthetized rats. The knee was either normal or acutely inflamed by kaolin/ carrageenan. During the topical application of omega-agatoxin IVA (P-type channel antagonist, 0.1 microM) onto the dorsal surface of the spinal cord, the responses to innocuous and noxious pressure applied to the normal knee were increased to respectively 124 +/- 42% and 114 +/- 23% of predrug values (mean +/- SD, P < 0.05, 14 neurons). By contrast, in rats with an inflamed knee, the responses to innocuous and noxious pressure applied to the knee were reduced to respectively 72 +/- 19 and 73 +/- 22% of baseline (mean +/- SD, P < 0.01, 13 neurons). In the same neurons, omega-agatoxin IVA slightly increased the responses to pressure on the non-inflamed ankle whether the knee was normal or inflamed. Thus P-type calcium channels seem to acquire a predominant importance in the excitation of spinal cord neurons by mechanosensory input from inflamed tissue and hence in the generation of inflammatory pain. By contrast, the Q-type channel antagonist, omega-conotoxin MVIIC (1 or 100 microM), had no significant effect upon responses to innocuous or noxious pressure applied to either normal or inflamed knees (25 neurons).
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Authors | J Nebe, H Vanegas, V Neugebauer, H G Schaible |
Journal | The European journal of neuroscience
(Eur J Neurosci)
Vol. 9
Issue 10
Pg. 2193-201
(Oct 1997)
ISSN: 0953-816X [Print] France |
PMID | 9421179
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Calcium Channel Blockers
- Calcium Channels
- Calcium Channels, N-Type
- Spider Venoms
- omega-Agatoxin IVA
- voltage-dependent calcium channel (P-Q type)
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Topics |
- Animals
- Calcium Channel Blockers
(pharmacology)
- Calcium Channels
(physiology)
- Calcium Channels, N-Type
- Electrophysiology
(methods)
- Inflammation
- Joints
(innervation, physiology, physiopathology)
- Male
- Neurons
(physiology)
- Pain
(physiopathology)
- Physical Stimulation
- Rats
- Rats, Wistar
- Spider Venoms
(pharmacology)
- Spinal Cord
(physiology, physiopathology)
- omega-Agatoxin IVA
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