Capsazepine as a selective antagonist of capsaicin-induced activation of C-fibres in guinea-pig bronchi.
We investigated the action of capsazepine, an antagonist of the actions of capsaicin on sensory neurones, on the contractile responses evoked by capsaicin or by electrical field stimulation (EFS) in guinea-pig bronchi. Capsazepine (10(-5) M) selectively inhibited responses to capsaicin, producing a significant change in EC50 values but not the Hill coefficient (nH), suggesting that capsazepine acts as a competitive antagonist (apparent pKB = 5.12) whereas ruthenium red is a non-competitive antagonist. Capsazepine and ruthenium red were without effect on EFS-induced responses.
Belvisi
M G
MG
Department of Thoracic Medicine, National Heart and Lung Institute, Chelsea, London, UK.
Miura
M
M
Stretton
D
D
Barnes
P J
PJ
D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000294:innervation*; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects*; D012430:Ruthenium Red / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D012430:Ruthenium Red; D013779:Tetrodotoxin; C071423:capsazepine; D002211:Capsaicin