Enzymatically dissociated trigeminal ganglion neurons were used. Ca2+ currents were recorded using whole-cell patch-clamping as described 37. Currents were acquired with the Axopatch 200B amplifier (Molecular Devices, Sunnyvale, CA), filtered, and cell membrane capacitance and pipette series resistance were electronically compensated. The concentration-response relationships were determined by sequential application of the respective agonist in increasing concentrations. Two to three different concentrations were used with each cell in order to minimize desensitization. The results were pooled and the concentration-response curves were fit to the Hill equation. Data and statistical analyses were performed with Igor Pro (Lake Oswego, OR) and Prism 4.0 (GraphPad Software, Inc.) software packages, respectively.
