The effects of alterations in electrogenic Na+/K+ -pumping in guinea-pig isolated trachealis: their modulation by the epithelium.
1 An examination was made of the effect of epithelium removal on mechanical responses of guinea-pig isolated tracheal strips after inhibition or activation of electrogenic Na+/K+ -pumping. 2 The Na+/K+ -pump inhibitor ouabain (0.1-10 microM) evoked concentration-dependent contractions which were potentiated by epithelium removal. 3 K+-free solution, which inhibits Na+/K+-pumping, produced a slow, sustained relaxation in intact preparations. In epithelium-free preparations the relaxation was transient and of lesser magnitude. 4 The addition of K+ (10 or 30 mM), which activates Na+/K+-pumping, to preparations bathed in K+-free solution caused a relaxation of preparations under spontaneous tone or contracted with methacholine; the magnitude and duration of relaxation was greater in the epithelium-free preparations. Ouabain (0.1 microM) attenuated the relaxation to K+ in intact preparations and converted the response of epithelium-free preparations to a contraction. In the presence of a higher concentration of ouabain (1 microM), intact preparations contracted in response to K+. 5 In normal K+ solution, ouabain (0.1 microM) increased the sensitivity of intact preparations to methacholine but reduced their sensitivity to K+. Ouabain was without these effects in epithelium-free preparations. 6 Thus, responses of intact preparations to perturbations which affect electrogenic Na+/K+-pumping in trachealis are influenced by an epithelium-derived factor. The production of the factor may be linked to an epithelial Na+/K+-pump, or the factor may modulate the activity of an electrogenic Na+/K+-pump in the muscle.
Raeburn
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Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, WV 26505-2888.
Fedan
J S
JS
D000818:Animals; D001693:Biological Transport, Active; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008688:Methacholine Compounds / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D014132:Trachea / Q000187:drug effects / Q000378:metabolism
D008688:Methacholine Compounds; D010042:Ouabain; D012964:Sodium; D011188:Potassium