Mediator difference in contractions between trachea and bronchus of guinea pig induced by stimulation of C-fibers in vitro.
In trachea and bronchus of guinea pig in vitro, electric field stimulation (EFS) induced a rapid contraction (phase I) followed by a long-lasting contraction (phase II). The pretreatments of chlorphenamine (Chl) 1 mumol.L-1 and disodium cromoglycate (Cro) 10 mumol.L-1 reduced the tracheal contraction of phase II from 49 +/- 23 mg and 34 +/- 18 mg to 27 +/- 21 and 18 +/- 12 mg, respectively. The contractile responses of the tracheae to increasing concentrations of substance P (SP) 0.1-3.0 mumol.L-1 were reduced by the pretreatment of Cro 10 mumol.L-1 (P < 0.01). On the contrary, the contractile responses of the bronchi were not inhibited by Cro or Chl but were inhibited by pretreatment of atropine 1 mumol.L-1 from 61 +/- 36 mg to 36 +/- 15 mg. These results show that there are different mechanisms in the EFS-induced contractions between the trachea and bronchus; that different mediators amplify the phase II contractions.
Fang
L B
LB
Department of Pharmacology, Zhejiang Medical University, Hangzhou, China.
Yang
Q H
QH
Bian
R L
RL
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001980:Bronchi / Q000502:physiology*; D002744:Chlorpheniramine / Q000494:pharmacology; D004205:Cromolyn Sodium / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D009412:Nerve Fibers / Q000378:metabolism / Q000502:physiology*; D013373:Substance P / Q000378:metabolism*; D014132:Trachea / Q000502:physiology*
D013373:Substance P; D002744:Chlorpheniramine; D001285:Atropine; D006632:Histamine; D000109:Acetylcholine; D004205:Cromolyn Sodium