Studies into the mechanistic basis for local anesthetic action on transient receptor potential cation channel subfamily V member 1 in vitro
department or school: Medicine, Faculty of
department or school: Anesthesiology, Pharmacology and Therapeutics, Department of
data provider: DSpace
degree campus: UBCV
creator: Rivera, Ricardo Enrique
issued: 2013-04-16T09:16:21Z
issued: 2013
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Transient receptor potential subfamily V, member 1 (TRPV1) channels are important integrators of noxious stimuli with pronounced expression in nociceptive neurons. Local anesthetics have been shown to modulate these nonselective cation channels in vivo and in vitro. However, little is known about the specific interactions between local anesthetic molecules and TRPV1 channels. This thesis therefore was dedicated to examining the mechanistic basis by which local anesthetic compounds act on TRPV1 channels from a perspective of neuronal manipulation for nociceptive blockade. The experimental approach involved a series of in vitro laboratory studies where wild-type TRPV1, TRPV4, and mutant TRPV1 channels were expressed in Xenopus leavis oocytes and cation currents recorded using the two-electrode voltage clamp technique. QX-314 and lidocaine activated TRPV1 channels at millimolar concentrations, but not TRPV4 channels. The TRPV1 antagonist, capsazepine, blocked QX-314- and lidocaine-evoked inward currents through a vanilloid-dependent pathway. At sub-activating concentrations (< 1 mM), QX-314 potently inhibited capsaicin-evoked TRPV1 currents. This thesis’ main results establish that the quaternary lidocaine derivative, QX-314, exerts biphasic effects on TRPV1 channels, inhibiting capsaicin-evoked TRPV1 currents at lower (micromolar) concentrations and activating TRPV1 channels at higher (millimolar) concentrations. Further pharmacological characterization of amino-amide inhibition showed that QX-314 and lidocaine inhibit vanilloid- and proton-evoked currents in TRPV1 channels. Studies defining the molecular determinants of blockade revealed that lidocaine inhibits TRPV1 channels with nanomolar affinity, while the neutral derivative, benzocaine, does not, indicating that a titratable amine mediates the high-affinity block. Consistent with this hypothesis, extracellular tetraethylammonium (TEA) and tetramethylammonium (TMA) application produced potent, voltage-dependent p…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/44221
note: STUDIES INTO THE MECHANISTIC BASIS OF LOCAL ANESTHETIC ACTION ON TRANSIENT RECEPTOR POTENTIAL CATION CHANNEL SUBFAMILY V MEMBER 1 IN VITRO by RICARDO ENRIQUE RIVERA BSc., The University of Puerto Rico-Cayey, 2008 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate Studies (Pharmacology) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2013 © Ricardo Enrique Rivera, 2013 ii Abstract Transient receptor potential subfamily V, member 1 (TRPV1) channels are important integrators of noxious stimuli with pronounced expression in nociceptive neurons. Local anesthetics have been shown to modulate these nonselective cation channels in vivo and in vitro. However, little is known about the specific interactions between local anesthetic molecules and TRPV1 channels. This thesis therefore was dedicated to examining the mechanistic basis by which local anesthetic compounds act on TRPV1 channels from a perspective of neuronal manipulation for nociceptive blockade. The experimental approach involved a series of in vitro laboratory studies where wild- type TRPV1, TRPV4, and mutant TRPV1 channels were expressed in Xenopus leavis oocytes and cation currents recorded using the two-electrode voltage clamp technique. QX-314 and lidocaine activated TRPV1 channels at millimolar concentrations, but not TRPV4 channels. The TRPV1 antagonist, capsazepine, blocked QX-314- and lidocaine-evoked inward currents through a vanilloid-dependent pathway. At sub-activating concentrations (< 1 mM), QX-314 potently inhibited capsaicin-evoked TRPV1 currents. This thesis’ main results establish that the quaternary lidocaine derivative, QX-314, exerts biphasic effects on TRPV1 channels, inhibiting capsaicin-evoked TRPV1 currents at lower (micromolar) concentrations and activating TRPV1 channels at higher (millimolar) concentrations. Further pharmacological characterization of amino-amide inhibition showed that QX-314 and lidocaine…
has type: Thesis/Dissertation
date issued: 2013-05
is shown at: 10.14288/1.0073676
language: eng
degree discipline: Pharmacology and Therapeutics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-ShareAlike 3.0 Unported
rights URI: http://creativecommons.org/licenses/by-sa/3.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/44221