TRPV1: Contribution to Retinal Ganglion Cell Apoptosis and Increased Intracellular Ca2 with Exposure to Hydrostatic Pressure

PURPOSE. Elevated hydrostatic pressure induces retinal ganglion cell (RGC) apoptosis in culture. The authors investigated whether the transient receptor potential vanilloid 1 (TRPV1) channel, which contributes to pressure sensing and Ca2-dependent cell death in other systems, also contributes to pressure-induced RGC death and whether this contribution involves Ca2. METHODS. trpv1 mRNA expression in RGCs was probed with the use of PCR and TRPV1 protein localization through immunocyto-chemistry. Subunit-specific antagonism (iodo-resiniferatoxin) and agonism (capsaicin) were used to probe how TRPV1 activation affects the survival of isolated RGCs at ambient and elevated hydrostatic pressure (70 mm Hg). Finally, for RGCs under pres-sure, the authors tested whether EGTA chelation of Ca2 im-proves survival and whether, with the Ca2 dye Fluo-4 AM