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Modulation of intracellular calcium influences capsaicin-induced currents of TRPV-1 and voltage-activated channel currents in nociceptive neurones.
- Source :
-
Journal of the peripheral nervous system : JPNS [J Peripher Nerv Syst] 2007 Dec; Vol. 12 (4), pp. 277-84. - Publication Year :
- 2007
-
Abstract
- Modulation of intracellular calcium ([Ca2+](i)) has a major impact on processing of nociceptive signals. While activation of the transient receptor potential vanilloid-1 (TRPV-1) receptor/channel complex increases [Ca2+](i) by Ca2+ entry from the extracellular space, as well as by Ca2+ release from intracellular stores, the Ca2+ entry through voltage-activated calcium channels (VACCs) is modulated simultaneously. To clarify the relations between [Ca2+](i) and the activation of TRPV-1 receptor and VACC currents [I(TRPV-1) and I(Ca(V))], we performed voltage clamp experiments using Ba2+ as well as Ca2+ as a charge carrier. The TRPV-1 receptor was activated by the application of 0.5 microM capsaicin, and the currents through TRPV-1 and VACC [I(TRPV-1) and I(Ca(V))] were measured either when Ca2+ release from intracellular stores was pharmacologically promoted or prevented. With Ba2+ as the divalent charge carrier, capsaicin (0.5 microM) reduced I(Ca(V)) (elicited by a depolarization to 0 mV) to 52.7 +/- 4.5% of baseline, and the elicited current through the TRPV-1 receptor/channel complex was 6.6 +/- 0.9% [relative to peak I(Ca(V))]. These currents were significantly different when Ca2+ was used as charge carrier: the I(Ca(V)) reductions were decreased to 17.8 +/- 5.9% of baseline, while the I(TRPV-1) was as high as 57.1 +/- 9.1% of I(Ca(V)). Increases of [Ca2+](i) by releasing Ca2+ from intracellular stores (using caffeine, 10 mM) before the application of capsaicin increased the I(TRPV-1) (14.1 +/- 7%), while the I(Ca(V)) was decreased to 51.6 +/- 4.9% compared with control. A preexperimental partial reduction of the Ca2+ release from the stores by dantrolene (5 microM) resulted in less pronounced effects [24.5 +/- 8.8%, relative to peak I(Ca(V))] for I(TRPV-1), and a reduction to 35.4 +/- 3% of baseline for I(Ca(V)) after capsaicin application.
- Subjects :
- Animals
Intracellular Fluid drug effects
Neurons, Afferent drug effects
Pain physiopathology
Rats
Rats, Inbred Lew
Rats, Wistar
TRPV Cation Channels agonists
Calcium physiology
Calcium Channels physiology
Capsaicin pharmacology
Intracellular Fluid physiology
Neurons, Afferent physiology
TRPV Cation Channels physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1529-8027
- Volume :
- 12
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of the peripheral nervous system : JPNS
- Publication Type :
- Academic Journal
- Accession number :
- 18042138
- Full Text :
- https://doi.org/10.1111/j.1529-8027.2007.00149.x