Effects of K + channel inhibitors on the basal tone and KCl- or methacholine-induced contraction of mouse trachea

• Published in: European journal of pharmacology 1998-04, Vol.346 (2), p.255-260
• Main Authors: Li, Liang, Paakkari, Ilari, Vapaatalo, Heikki
• Format: Article
• Language: English
• Subjects: Air breathing; Animals; Biological and medical sciences; Contraction; Female; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; K + channel inhibitor; Male; Methacholine Chloride - antagonists & inhibitors; Methacholine Chloride - pharmacology; Mice; Mice, Inbred BALB C; Muscarinic Agonists - pharmacology; Muscle Tonus - drug effects; Muscle, Smooth - drug effects; Potassium Channel Blockers; Potassium Chloride - antagonists & inhibitors; Potassium Chloride - pharmacology; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Smooth muscle, airway; Trachea - drug effects; Trachea, mouse; Vertebrates: respiratory system
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/S0014-2999(98)00074-0

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 Ca 2+-dependent K + channels can potentiate KCl- 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.