Dataset Information

Activation of TRPA1 by membrane permeable local anesthetics.

ABSTRACT:

Background

Low concentrations of local anesthetics (LAs) suppress cellular excitability by inhibiting voltage-gated Na? channels. In contrast, LAs at high concentrations can be excitatory and neurotoxic. We recently demonstrated that LA-evoked activation of sensory neurons is mediated by the capsaicin receptor TRPV1, and, to a lesser extent by the irritant receptor TRPA1. LA-induced activation and sensitization of TRPV1 involves a domain that is similar, but not identical to the vanilloid-binding domain. Additionally, activation of TRPV1 by LAs involves PLC and PI(4,5)P?-signalling. In the present study we aimed to characterize essential structural determinants for LA-evoked activation of TRPA1.

Results

Recombinant rodent and human TRPA1 were expressed in HEK293t cells and investigated by means of whole-cell patch clamp recordings. The LA lidocaine activates TRPA1 in a concentration-dependent manner. The membrane impermeable lidocaine-derivative QX-314 is inactive when applied extracellularly. Lidocaine-activated TRPA1-currents are blocked by the TRPA1-antagonist HC-030031. Lidocaine is also an inhibitor of TRPA1, an effect that is more obvious in rodent than in human TRPA1. This species-specific difference is linked to the pore region (transmembrane domain 5 and 6) as described for activation of TRPA1 by menthol. Unlike menthol-sensitivity however, lidocaine-sensitivity is not similarly determined by serine- and threonine-residues within TM5. Instead, intracellular cysteine residues known to be covalently bound by reactive TRPA1-agonists seem to mediate activation of TRPA1 by LAs.

Conclusions

The structural determinants involved in activation of TRPA1 by LAs are disparate from those involved in activation by menthol or those involved in activation of TRPV1 by LAs.

SUBMITTER: Leffler A

PROVIDER: S-EPMC3179737 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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Publications

Activation of TRPA1 by membrane permeable local anesthetics.

Leffler Andreas A Lattrell Anja A Kronewald Sergej S Niedermirtl Florian F Nau Carla C

Molecular pain 20110823

<h4>Background</h4>Low concentrations of local anesthetics (LAs) suppress cellular excitability by inhibiting voltage-gated Na⁺ channels. In contrast, LAs at high concentrations can be excitatory and neurotoxic. We recently demonstrated that LA-evoked activation of sensory neurons is mediated by the capsaicin receptor TRPV1, and, to a lesser extent by the irritant receptor TRPA1. LA-induced activation and sensitization of TRPV1 involves a domain that is similar, but not identical to the vanilloi ...[more]

PMID: 21861907

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Project description:BACKGROUND:Breast cancer accounts for nearly a quarter of all cancers in women worldwide, and more than 90% of women diagnosed with breast cancer undergo mastectomy or breast-conserving surgery. Retrospective clinical studies have suggested that use of regional anesthesia leads to improved patient outcomes. Laboratory studies have reported that breast cancer cells are inhibited by some local anesthetics at millimolar concentration. Here, we present a comprehensive analysis of the effects of six common local anesthetics on two human breast cancer cell lines. We used concentrations ranging from those corresponding to plasma levels during regional block by local anesthetic (plasma concentration) to those corresponding to direct infiltration of local anesthetic. METHODS:Human breast cancer cell lines, MDA-MB-231 and MCF7, were incubated with each of six local anesthetics (lidocaine, mepivacaine, ropivacaine, bupivacaine, levobupivacaine, and chloroprocaine) (10 ?M ~?10 mM) for 6 to 72 h. Assays for cell viability, cytotoxicity, migration, and cell cycle were performed. RESULTS:High concentrations (>?1 mM) of local anesthetics applied to either MDA-MB-231 or MCF7 cells for 48 h significantly inhibited cell viability and induced cytotoxicity. At plasma concentrations (~?10 ?M) for 72 h, none of the local anesthetics affected cell viability or migration in either cell line. However, at 10?×?plasma concentrations, 72-h exposure to bupivacaine, levobupivacaine or chloroprocaine inhibited the viability of MDA-MB-231 cells by >?40% (p?<?0.001). Levobupivacaine also inhibited the viability of MCF7 cells by 50% (p?<?0.001). None of the local anesthetics affected the viability of a non-cancerous breast cell line, MCF10A. MDA-MB-231 cell migration was inhibited by 10?×?plasma concentrations of levobupivacaine, ropivacaine or chloroprocaine and MCF7 cell migration was inhibited by mepivacaine and levobupivacaine (p?<?0.05). Cell cycle analysis showed that the local anesthetics arrest MDA-MB-231 cells in the S phase at both 1?×?and 10?×?plasma concentrations. CONCLUSIONS:Local anesthetics at high concentrations significantly inhibited breast cancer cell survival. At 10?×?plasma concentrations, the effect of local anesthetics on cancer cell viability and migration depended on the exposure time, specific local anesthetic, specific measurement endpoint and specific cell line.

Dataset Information

Activation of TRPA1 by membrane permeable local anesthetics.

Background

Results

Conclusions

Publications

Activation of TRPA1 by membrane permeable local anesthetics.

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