Inhibitory effect of tetrandrine on C fiber activation-induced contractions in trachea and bronchus of guinea pig.
OBJECTIVE
To study the inhibitory effects of tetrandrine (Tet) on an activation of the sensory nervous C fibers in isolated trachea and bronchus of guinea pig.


METHODS
The electric field stimulation induced a phase II contraction of the preparations, which was due to an activation of the C fifers. The effects of Tet on phase II contraction were analyzed.


RESULTS
Tet 0.3-30 mumol.L(-1) inhibited phase II contractions in a concentration-dependent manner. That phase II contractions inhibited by Tet 1 mumol.L(-1) were 40 +/- 38% and 75 +/- 22% of control in tracheae and bronchi respectively. After pretreatment with chlorphenamine or atropine phase II contraction were still reduced by Tet 1 mumol.L(-1), inhibitory rates being 70 +/- 16% and 64 +/- 16% of control, respectively. The contractile responses of the preparations to exogenous substance P, however, were unaffected by treatment with Tet 1 mumol.L(-1).


CONCLUSIONS
Tet 1 mumol.L(-1) inhibits phase II contraction, related to the inhibition of local release of neuropeptides from C fibers of guinea pig airway.
Fang
L B
LB
Department of Pharmacology, Zhejiang Medical University, Hangzhou, China.
Yang
Q H
QH
Bian
R L
RL
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D044182:Benzylisoquinolines; D001980:Bronchi / Q000187:drug effects; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009412:Nerve Fibers / Q000502:physiology*; D014132:Trachea / Q000187:drug effects
D000470:Alkaloids; D044182:Benzylisoquinolines; C009438:tetrandrine