Figure 4

OAG-induced inward current is inhibited by TRPV1 blockers in heterologous expression system. (Aa) Currents generated by repetitive 100 μM OAG application showed recovery from desensitization. The intervals of each trace were 1 min, 2 min, and 3 min as indicated. (Ab) The repeated application of OAG currents showed full recovery after 5 min on a different cell. (c, upper panel) 100 μM OAG induced inwarnd current in HEK cell expressing TRPV1 which responded to 1 μM capsaicin. (c, lower panel) 100 μM OAG elicited inward currents that were abolished by 10 μM CZP in TRPV1-transfected cells. OAG did not induce any current in untransfected cells. (d) Summary of the current responses to 1 μM capsaicin, 100 μM OAG, and 100 μM OAG with 10 μM CZP, as measured by peak current amplitude. The asterisk showed significant difference in OAG-induced Ca²⁺transient blocked by CZP (t-test, P < 0.05). (g) Co²⁺ uptake experiments further verified TRPV1 activation by 100 μM OAG. Co²⁺ uptake induced by 100 μM OAG (upper middle panel) was abolished by the TRPV1 antagonist, 100 μM 6-iodonordihydrocapsaicin (6-CAP) (lower middle panel). Lower panel shows the same experimental condition for capsaicin.