Effects of K+ channel inhibitors on the basal tone and KCl- or methacholine-induced contraction of mouse trachea.
The present study examined the effects of K+ channel inhibitors on the basal tone and on KCl- or methacholine-induced contraction of the mouse-isolated trachea. Glibenclamide and iberiotoxin, procaine, quinine and tetraethylammonium did not induce any contraction of the indomethacin-treated mouse trachea. 4-Aminopyridine induced concentration-dependent contraction. This action of 4-aminopyridine was abolished by atropine and reduced by tetrodotoxin and nifedipine. Glibenclamide failed to modify KCl- or methacholine-induced contraction. Iberiotoxin and 4-aminopyridine potentiated KCl- and methacholine-induced contractions. Nifedipine, procaine, quinine and tetraethylammonium inhibited KCl- and methacholine-induced contractions. These data suggest that the closure of large Ca2+-dependent K+ channels can potentiate KCI- and methacholine-induced contraction. The effects of 4-aminopyridine on the mouse trachea reflect chiefly activation of muscarinic receptors. Procaine, quinine and tetraethylammonium inhibit depolarization-induced and receptor-mediated contractions of the mouse-isolated trachea.
Li
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Institute of Biomedicine, Department of Pharmacology and Toxicology, University of Helsinki, Finland.
Paakkari
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I
Vapaatalo
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D000818:Animals; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D016210:Methacholine Chloride / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009129:Muscle Tonus / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D026902:Potassium Channel Blockers; D011189:Potassium Chloride / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects*
D018721:Muscarinic Agonists; D026902:Potassium Channel Blockers; D016210:Methacholine Chloride; D011189:Potassium Chloride