The effects of alterations in electrogenic Na+/K+-pumping in guinea- pig isolated trachealis: their modulation by the epithelium.
Br J Pharmacol 1989 Oct; 98(2):343-350
Epithelial modulation of alterations in the electrogenic sodium (Na+)/potassium (K+) pump of tracheal strips was investigated. Organ baths of epithelium free tracheal strips from male English- short-hair-guinea-pigs were used to derive concentration response curves for the addition of 1.6 fold K+, 3.2 fold methacholine, or 10 fold ouabain; ouabain's effect on K+ and methacholine curves was also assessed. The addition of 10 or 30 millimolar (mM) K+ to strips in K+ free modified Kreb/Henseleit (MKH) solution was also investigated. Preparation tone remained spontaneous or was increased with methacholine prior to addition of K+ (10 or 30mM) or ouabain (0.1 or 1 micromolar) then K+. The effects of inhibitor mixtures and indomethacin were also assessed. Ouabain evoked dose dependent contractions potentiated by epithelium removal. The absence of K+ was associated with transient low magnitude pump relaxation in epithelium free strips but a slow sustained relaxation in intact strips. K+ addition resulted in relaxation of preparations under spontaneous tone or contracted with methacholine; duration and degree were greater in epithelium free samples. Lower concentrations of ouabain lessened K+ induced relaxation in intact preparations but caused relaxed epithelium free preparations to contract; higher concentrations were related to preparation contraction with K+ addition. Ouabain increased the methacholine sensitivity of intact preparations with normal K+ levels; similar effects were not seen in epithelium free solutions. The authors conclude that an epithelial derived factor is responsible for modulation of the trachealis pump.
NIOSH-Author; In-vitro-studies; Electrophysiological-effects; Muscle-function; Muscle-physiology; Cellular-transport-mechanism; Dose-response; Laboratory-animals; Respiration
British Journal of Pharmacology