Artemin increases Ca
activity through TRPA1 and TRPV1 in primary cultured DRG neurons. A-F, I-N: Examples of a Fura-2-based Ca2+ imaging method with DRG primary cultured neurons in vehicle- (A-C, I-K) or artemin-treated groups (D-F, L-N). The images are before stimuli (A, D, I, L), after KCL (B, E, J, M), and after capsaicin (C, F) or AITC (K, N). G and O: The percentage of TRPV1-(G) or TRPA1- (O) expressing neurons was significantly larger in artemin-treated neurons than amongst vehicle-treated ones. TRPV1 positive neurons were examined by application of capsaicin, and TRPA1-expressing neurons were confirmed by the application of AITC (100 μM) and capsaicin (1 μM). H and P: The increase in the Fura ratio (the ratio of 340/380 nm values) between the two treated groups was compared. The artemin-treated DRG neurons showed higher Fura ratios after application of capsaicin than the vehicle-treated ones (***p < 0.001, H). However, the changes in Fura ratios in AITC/capsaicin responsive neurons did not show a significant difference between the artemin and vehicle-treated groups (P). (mean ± SEM, *p < 0.05, ***p < 0.001, compared with the vehicle group).