title: Potentiation of rabbit trigeminal responses to capsaicin in a low pH environment.
abstract: The sensitivity of 35 adult rabbit trigeminal ganglion neurons to low pH (pH 6.0), 10 microM capsaicin (CAP) and 10 microM capsaicin at low pH (CAP@pH6.0) was studied using voltage-clamp whole-cell recording techniques. Neurons responded to pH 6.0 with a transient inward current, followed by a more slowly activating (sustained) net inward current. Responses to capsaicin showed only a sustained current. Capsaicin caused an increase in membrane conductance, whereas responses to low pH were associated with either a net increase or decrease in conductance. A subset of neurons (n = 14) responded to CAP@pH6.0 with a sustained current which exceeded the sum of the peak sustained currents evoked by CAP and pH 6.0 applied singularly by approximately a factor of 4. The current was associated with a substantial increase in membrane conductance. The present results indicate that, in addition to a direct conductance activating effect, protons have the ability to enhance the current evoked by capsaicin.
authors.affiliation: Division of Neurosurgery (L472), Oregon Health Sciences University, Portland 97201.
authors.forename: M E
authors.initials: ME
authors.lastname: Martenson
authors.forename: S L
authors.initials: SL
authors.lastname: Ingram
authors.forename: T K
authors.initials: TK
authors.lastname: Baumann
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D008297:Male; D009474:Neurons / Q000502:physiology*; D011817:Rabbits; D012668:Trigeminal Ganglion / Q000502:physiology*
chemical_list: D002211:Capsaicin