(112) Identification and Characterization of Transient Receptor Potential (TRP) Channels in Human Vagina Smooth Muscle Cells

Abstract Introduction Transient Receptor Potential (TRP) channels are transmembrane protein complexes, acting as non-selective cation channels, activated by a wide range of mechanical and thermal stimuli. TRP channels can also be activated and modulated by endogenous and specific chemical ligands. Mammals express these receptors in several tissues, where they exert a pivotal role in themodulation of different processes such as mechano-transduction, thermal nociception and flogosis. We previously investigated the role of human vagina smooth muscle cells (hvSMCs) isolated from vagina tissue in the inflammatory response. Objective The aim of the present study was the identification and functional characterization ofTRP channels in hvSMCs, thus exploring their potential role as mediators of inflammatory process inthe human vagina. Methods The membrane passive properties of hvSMCs and the functionality of the TRP channelsmainly expressed in these cells were assessed using whole-cell patch clamp technique. Specifically, ion currents flowing through membrane channels were recorded before and after the administration of thermal (temperatures above/under thermal threshold) and specific chemical agonists (capsaicin, menthol and allyl isothiocyanate) stimuli. The mRNA expression of TRPs channels in human vaginal tissue and in derived-hvSMCs was performed by semi-quantitative RT-PCR. Moreover, immunopositivity for TRPs was tested by immunohistochemistry. Results A prevalent mRNA relative expression of TRPV1 and TRPA1 channels, compared to TRPM8, was observed in hvSMCs. Whole-cell patch clamp studies performed on hvSMCs before and after both thermal and chemical stimulations did not show a significant difference in passive membrane properties (resting potential, membrane capacitance, membrane resistance and conductance). Conversely, a significant functional responsiveness was recorded in response to both thermic andchemical activation, consistently with their level of expression. Conclusions These preliminary findings indicate that TRP subtypes channels TRPA1, TRPV1 and TRPM8 are actively expressed in the smooth muscle cells isolated from human vagina. Considering the pivotal involvement of these channels in the inflammatory process, these results could be a first step to consider TRP channels as a possible target in inflammatory gynaecological diseases. Disclosure No.