[3H]A-778317 [1-((R)-5-tert-butyl-indan-1-yl)-3-isoquinolin-5-yl-urea]: a novel, stereoselective, high-affinity antagonist is a useful radioligand for the human transient receptor potential vanilloid-1 (TRPV1) receptor.
1-((R)-5-tert-butyl-indan-1-yl)-3-isoquinolin-5-yl-urea (A-778317) is a novel, stereoselective, competitive antagonist that potently blocks transient receptor potential vanilloid-1 (TRPV1) receptor-mediated changes in intracellular calcium concentrations (pIC50 = 8.31 +/- 0.13). The (S)-stereoisomer, 1-((S)-5-tert-butyl-indan-1-yl)-3-isoquinolin-5-yl-urea (A-778316), is 6.8-fold less potent (pIC50 = 7.47 +/- 0.07). A-778317 also potently blocks capsaicin and acid activation of native rat TRPV1 receptors in dorsal root ganglion neurons. A-778317 was tritiated ([3H]A-778317; 29.3 Ci/mmol) and used to study recombinant human TRPV1 (hTRPV1) receptors expressed in Chinese ovary cells (CHO) cells. [3H]A-778317 labeled a single class of binding sites in hTRPV1-expressing CHO cell membranes with high affinity (KD = 3.4 nM; Bmax = 4.0 pmol/mg protein). Specific binding of 2 nM [3H]A-778317 to hTRPV1-expressing CHO cell membranes was reversible. The rank-order potency of TRPV1 receptor antagonists to inhibit binding of 2 nM [3H]A-778317 correlated well with their functional potencies in blocking TRPV1 receptor activation. The present data demonstrate that A-778317 blocks polymodal activation of the TRPV1 receptor by binding to a single high-affinity binding site and that [3H]A-778317 possesses favorable binding properties to facilitate further studies of hTRPV1 receptor pharmacology.
Bianchi
Bruce R
BR
Department of Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, R4PM, AP9A/2, 100 Abbott Park Rd, Abbott Park, IL 60064-6123, USA.
El Kouhen
Rachid
R
Neelands
Torben R
TR
Lee
Chih-Hung
CH
Gomtsyan
Arthur
A
Raja
Shirish N
SN
Vaidyanathan
Sriajan N
SN
Surber
Bruce
B
McDonald
Heath A
HA
Surowy
Carol S
CS
Faltynek
Connie R
CR
Moreland
Robert B
RB
Jarvis
Michael F
MF
Puttfarcken
Pamela S
PS
D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D020013:Calcium Signaling / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007546:Isoquinolines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D008024:Ligands; D015394:Molecular Structure; D009475:Neurons, Afferent / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D013237:Stereoisomerism; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors*; D014162:Transfection; D014316:Tritium; D014508:Urea / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology
C523980:1-(5-tertbutylindan-1-yl)-3-isoquinolin-5-ylurea; D007546:Isoquinolines; D008024:Ligands; D011994:Recombinant Proteins; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D014316:Tritium; D014508:Urea