not-yet-known not-yet-known not-yet-known unknown The reagents 3-(3,4-dihydroxyphenyl) propanoic acid (DHCA), fluorescein isothiocyanate (FL), N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) were obtained from Sigma-Aldrich (Shanghai, China). Capsaicin and capsazepine were purchased from Aladdin (Shanghai, China). Fluo 4-AM was purchased from Invitrogen (Shanghai, China).