Capsazepine block of voltage-activated calcium channels in adult rat dorsal root ganglion neurones in culture |
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Authors: | R J Docherty J C Yeats A S Piper |
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Affiliation: | Sandoz Institute for Medical Research, 5 Gower Place, London WC1E 6BN;*Department of Pharmacology, United Medical and Dental Schools of Guy''s and St Thomas'', Lambeth Palace Road, London SE1 7EH |
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Abstract: | - We have found that capsazepine, a competitive antagonist at the vanilloid (capsaicin) receptor, blocks voltage-activated calcium currents in sensory neurones.
- The block of calcium current was slow to develop with a half time of about one minute at 100 μM and lasted for the duration of the experiment. The rate of block of calcium current was strongly concentration-dependent.
- The EC50 for the blocking effect at 0 mV was 7.7±1.4 μM after 6 min exposure to capsazepine. The EC50 at equilibrium was estimated to be 1.4±0.2 μM.
- The block of calcium current showed some voltage-dependence but there was no indication of any selectivity of action for a calcium channel subtype. The characteristics of the blocking action of capsazepine on the residual current of cells which were pretreated with either □Omega;-conotoxin or nimodipine were similar to control.
- The data suggest that capsazepine, in addition to its competitive antagonism of vanilloid receptors, has a non-specific blocking action on voltage-activated calcium channels which should be taken into account when interpreting the effects of this substance on intact preparations in vitro or in vivo.
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Keywords: | Capsaicin capsazepine sensory neurone calcium current calcium channel calcium antagonist |
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