AJP - Gastrointestinal and Liver Physiology, Vol 245, Issue 6 797-G807, Copyright © 1983 by American Physiological Society
Cl- - and K+-related fluctuations of ionic current through oxyntic cells in frog gastric mucosa
W. Zeiske, T. E. Machen and W. Van Driessche
Transport and conductance pathways for Cl- and K+ were studied in frog
gastric mucosa using noise analysis techniques. The current-noise power
spectra exhibited both Cl- - and K+-dependent characteristics. In Cl-
-containing solutions, reductions in Cl- transport were associated with
reductions of the overall noise power. Such changes appeared to reflect the
movement of Cl- through the apical (mucosal) membranes of oxyntic cells. In
Cl- -free solutions a K+-dependent Lorentzian component was detected in the
power spectrum when applying a mucosally or serosally directed
transepithelial K+ concentration gradient. This component was enhanced by
1) stimulating the oxyntic cells with histamine and 2) appropriate voltage
clamping. It was reduced by mucosal Ba2+ in resting tissues and enhanced by
mucosal Ba2+ in stimulated tissues. The K+ noise measured in gastric
mucosae in Cl- -free solutions appeared also to be generated at the apical
membranes of oxyntic cells. This is in analogy to previous findings in
other gastrointestinal epithelia with fluctuating apical K+ channels. In
the gastric mucosa these channels may play a key role in the mechanism of
electrogenic H+ secretion.
