title: Cloning and functional characterization of the guinea pig vanilloid receptor 1.
abstract: We have cloned a guinea pig Vanilloid receptor 1 (VR1) from a dorsal root ganglion cDNA library and expressed it in CHO cells. The receptor has been functionally characterized by measuring changes in intracellular calcium produced by capsaicin, low pH and noxious heat. Capsaicin produced a concentration-dependent increase in intracellular calcium in guinea pig VR1-CHO cells with an estimated EC(50) of 0.17 +/- 0.0065 micro M, similar to that previously reported for rat and human VR1. Olvanil and resiniferatoxin were also effective agonists (EC(50) values of 0.0087 +/- 0.0035 micro M and 0.067 +/- 0.014 micro M, respectively), but 12-phenylacetate 13-acetate 20-homovanillate (PPAHV) and anandamide showed little agonist activity up to 10 micro M. As with human and rat VR1, guinea pig VR1 was also activated by pH below 6.0 and by noxious heat (>42 degrees C). Capsazepine acted as an antagonist of capsaicin responses in guinea pig VR1-CHO cells (IC(50) of 0.324 +/- 0.041 micro M ), as seen at rat VR1. However, in contrast to its lack of activity against pH and heat responses at rat VR1, capsazepine was an effective antagonist of these responses at guinea pig VR1. Capsazepine displayed an IC(50) of 0.355 +/- 25 micro M against pH 5.5, and provided complete blockade of heat responses at 1 micro M. Thus, capsazepine can significantly inhibit calcium influx due to heat and pH 5.5 at guinea pig VR1 and human VR1 but is inactive against these activators at rat VR1.
authors.affiliation: Novartis Institute for Medical Sciences, 5 Gower Place, WC1E 6BN, London, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Savidge
authors.forename: Clare
authors.initials: C
authors.lastname: Davis
authors.forename: Kirti
authors.initials: K
authors.lastname: Shah
authors.forename: Sian
authors.initials: S
authors.lastname: Colley
authors.forename: Elsa
authors.initials: E
authors.lastname: Phillips
authors.forename: Sam
authors.initials: S
authors.lastname: Ranasinghe
authors.forename: Janet
authors.initials: J
authors.lastname: Winter
authors.forename: Peter
authors.initials: P
authors.lastname: Kotsonis
authors.forename: Humphrey
authors.initials: H
authors.lastname: Rang
authors.forename: Peter
authors.initials: P
authors.lastname: McIntyre
mesh_terms: D000331:Aequorin / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002908:Chronic Disease; D003001:Cloning, Molecular; D006224:Cricetinae; D005456:Fluorescent Dyes; D016257:Fura-2; D006168:Guinea Pigs; D006321:Heart; D006863:Hydrogen-Ion Concentration; D008163:Luminescent Measurements; D008969:Molecular Sequence Data; D010146:Pain / Q000188:drug therapy; D051381:Rats; D011955:Receptors, Drug / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics*; D050916:TRPV Cation Channels
chemical_list: D005456:Fluorescent Dyes; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D000331:Aequorin; C071423:capsazepine; D002211:Capsaicin; D002118:Calcium; D016257:Fura-2