Construction of a stable cell line uniformly expressing the rat TRPV1 receptor.

We constructed and analyzed a new cell line called HT5-1, which stably expresses an enhanced green fluorescent protein-tagged version of the rat vanilloid receptor 1 (VR1/TRPV1). The fluorescent receptor allowed easy measurement of receptor expression and expression level-based purification of cells via fluorescence-activated cell sorting. The HT5-1 cell line was compared to cells transiently transfected with the fluorescent receptor, to cells expressing the native rat vanilloid receptor, and to isolated capsaicin-sensitive rat trigeminal sensory neurons. Fura-2 microfluorimetry measurements of the calcium influx upon capsaicin induction showed that, by contrast to transiently transfected cells, HT5-1 cells respond uniformly to the stimulation, due to the similar level of receptor expression in individual cells. HT5-1 cells showed similar behaviour to isolated trigeminal root ganglion neurons, including marked tachyphylaxis upon repeated capsaicin induction, and a lack of calcium ion release from intracellular storage sites.