Premium
The effects of alterations in electrogenic Na + /K + ‐pumping in guinea‐pig isolated trachealis: their modulation by the epithelium
Author(s) -
Raeburn David,
Fedan Jeffrey S.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12602.x
Subject(s) - trachealis muscle , ouabain , chemistry , epithelium , biophysics , ion transporter , respiratory epithelium , endocrinology , medicine , membrane potential , biochemistry , sodium , biology , membrane , charybdotoxin , organic chemistry , genetics
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 μ m ) 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 m m ), 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 μ m ) 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 μ m ), intact preparations contracted in response to K + . 5 In normal K + solution, ouabain (0.1 μ m ) 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.