2.5 Drugs
H2O2,
HC-03003, AITC, capsaicin,
tetrodotoxin (TTX) and Carbachol were purchased from Sigma-Aldrich
(Darmstadt, USA). While PGE2, SP and a selective antagonist of
neurokin-2 receptors (NK2Rs), SR 48968, were sourced from MCE (New
Jersey, USA).
Stock solution of capsaicin were prepared in 100% ethanol and stored at
−20 ℃ until use. AITC, SR 48968, PGE2, and SP solutions were made in
dimethyl sulfoxide and diluted immediately before use. TTX was dissolved
in deionized water. The final concentrations of ethanol or dimethyl
sulfoxide were <0.1%. In all experimental groups, at least
one parallel control experiment was carried out in vehicle. The vehicles
we used had no pharmacological effects on the tone of preparations or
agonist-induced contractions. Chemicals were used at concentrations
shown to be effective in preliminary experiments, or at concentrations
used in studies published previously[29, 30].