[Effect of ciprofloxacin on contractile responses of canine airway smooth muscle].
To elucidate whether the new quinolone ciprofloxacin affects cholinergic neuto-effector transmission in the airway, we studied canine isolated bronchial segments under isometric conditions in vitro. Intrapulmonary lobar or segmental bronchi were suspended in the organ chambers filled with Krebs-Henseleit solution, and the isometric tension was continuously recorded by a force-displacement transducer. Addition of ciprofloxacin (2 x 10(-3) M) attenuated the contractile responses to electrical field stimulation (EFS), so that the stimulus frequency required to produce a half-maximal contraction (ES50) increased from 1.2 +/- 0.2 to 1.5 +/- 0.2 Hz (p < 0.05), whereas it was without effect on those to exogenously administered acetylcholine. The decrease in the EFS-induced contraction produced by ciprofloxacin was concentration-dependent and was not influenced by propranolol or tetraethylammonium, but partially inhibited by ouabain. These results suggest that ciprofloxacin may inhibit cholinergic neuro-effector transmission in the airway smooth muscle by inhibiting the exocytotic release of acetylcholine, probably involving the stimulation of Na(+)-K(+)-ATPase and concomitant repolarization/hyperpolarization of cholinergic nerve terminals.
Tagaya
E
E
First Department of Medicine, Tokyo Women's Medical College.
Tamaoki
J
J
Takemura
H
H
Chiyotani
A
A
Konno
K
K
D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000294:innervation; D002939:Ciprofloxacin / Q000494:pharmacology*; D004285:Dogs; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation; D009435:Synaptic Transmission / Q000187:drug effects; D014630:Vagus Nerve / Q000187:drug effects
D002939:Ciprofloxacin