Influence of ouabain on the cholinergic neurotransmission in the canine trachea.
The effect of ouabain on the cholinergic neurotransmission of the trachea was investigated using isolated tracheal strips in dogs. Tracheal strips without epithelium were suspended in organ chambers filled with modified Krebs-Henseleit solution. Ouabain (3 X 10(-7)-10(-5) M) concentration-dependently caused a slow sustained tracheal contraction. The contractile response was significantly inhibited by 10(-6) M atropine and was enhanced by 10(-8) M physostigmine. The ouabain-induced tracheal contraction was unaffected by 10(-7) M tetrodotoxin, but was significantly reduced by 10(-3) M hemicholinium-3. In superfusion experiments, ouabain (10(-5) M) produced an increase in the ACh release. Superfusion with Ca(++)-free solution almost eradicated the ACh release and abolished the tracheal contraction induced by ouabain. omega-Conotoxin (5 X 10(-8) M), but not nicardipine (10(-6) M), inhibited significantly the increase in ACh release induced by ouabain. These results suggest that the ouabain-induced tracheal contraction may be mainly due to acceleration of presynaptic ACh release by enhancing the influx of Ca++, and the Ca(+)+ entry may occur through the N-type Ca(+)+ channels in the canine airway presynaptic site.
Tsuchiya
Y
Y
Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan.
Hosokawa
T
T
Kasuya
Y
Y
D000109:Acetylcholine / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism; D009529:Nicardipine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology*; D010275:Parasympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D010456:Peptides, Cyclic / Q000494:pharmacology; D011863:Radioimmunoassay; D009435:Synaptic Transmission / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D020960:omega-Conotoxins
D010456:Peptides, Cyclic; D020960:omega-Conotoxins; C053423:Conus magus toxin; D013779:Tetrodotoxin; D010042:Ouabain; D001285:Atropine; D009529:Nicardipine; D000109:Acetylcholine