Differences in sensitivity of vanilloid receptor 1 transfected to human embryonic kidney cells and capsaicin-activated channels in cultured rat dorsal root ganglion neurons to capsaicin receptor agonists

Heterologously expressed vanilloid receptor 1 (VR1), a cloned cDNA encoding for capsaicin (CAP)-sensitive currents, resembles the native CAP channels in cultured sensory neurons in channel property. But, the pharmacological p rofile of VR1 to various CAP analogs is not known. The stable expression of VR1 in human embryonic kidney (HEK) cells was generated and confirmed by r everse transcription-polymerase chain reaction and Western blots. VR1 expre ssed in HEK cells retained single-channel properties similar to those of th e native channels. When concentration-response relationships were compared, CAP and DA-5018.HCl, a synthetic analog of CAP, exhibited a greater potenc y in activating VR1 than the native channels in sensory neurons. In contras t, resiniferatoxin and its analog, phorbol 12-phenylacetate 13-acetate 20-h omovanillate, was more potent in activating the CAP-activated channels in c ultured sensory neurons than VR 1. Thus, the difference in pharmacological profiles of VR 1 and the native channels suggests the possible presence of subtypes of the CAP receptor or regulatory mechanisms associated with VR1. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.