OAG induces Ca2+ influx in rat DRG neurons that is blocked by capsazepine (CZP). (a) The representative trace of fura-2 ratiometric Ca2+ imaging reveal activation of TRPV1 by 100 μM OAG in capsaicin (CAP) responsive DRG neurons. Ca2+ transients were evoked by the application of 100 μM OAG, (b) whereas Ca2+ transients were blocked by the pretreatment of 10 μM CZP and (c) of 0 mM Ca2+ in the extracellular solution. The DRG neurons were exposed to 1 μM capsaicin to determine capsaicin-sensitivity in the end of each experiment. (d) Summary of Ca2+ transient responses to 1 μM capsaicin, 100 μM OAG, 100 μM OAG with 10 μM CZP, as measured by peak amplitude of ratio for each transient. The mean value of OAG-induced Ca2+ transient was 0.086 ± 0.012, while that of capsaicin-induced Ca2+ transient was 0.36 ± 0.032. The OAG-induced Ca2+ transient was blocked by 10 μM CZP (0.001 ± 0.003). Each p value was indicated on each bar group. (e) The concentration-response curve of OAG response in DRG neurons obtained from ratiometric Ca2+ imaging.