OAG-induced Ca2+ transients correlate with mRNA expression of TRPV1 in each DRG neuron. Combination of single-cell RT-PCR following Ca2+ imaging (n = 10) revealed an association between expression of TRPV1 and the responsiveness to both OAG and capsaicin. DRG neurons responsive to 100 μM OAG and 1 μM capsaicin (Number 1 and 2 on (a), n = 6/10) expressed TRPV1 (n = 6/6), whereas DRG neurons unresponsive to 100 μM OAG and 1 μM capsaicin did not (number 3 on a, n = 4/4). Most cells (n = 9/10) expressed TRPC6 and some of them did not respond to 100 μM OAG (n = 4/9). (a) Three images represent fura-2 ratio images before and during 100 μM OAG and 1 μM capsaicin applications. Traces show Ca2+ transients in response to OAG or capsaicin application. (b) Acutely prepared DRG tissues showed the RNA expression level on TRP subfamilies. (c) Single cell RT-PCR results showed the mRNA level of TRP subfamilies. Numbers indicate each cell shown in single cell RT-PCR results.