AJP - Gastrointestinal and Liver Physiology, Vol 258, Issue 4 631-G636, Copyright © 1990 by American Physiological Society
Effect of histamine on the basolateral K+ conductance of frog stomach oxyntic cells and surface epithelial cells
L. Debellis, S. Curci and E. Fromter
Istituto di Fisiologia Generale, Universita di Bari, Italy.
The transepithelial potential difference (Vt) and resistance (Rt) and the
basolateral cell membrane potential (Vs) of oxyntic cells (OC) and surface
epithelial cells (SEC) were measured in isolated stomachs of Rana
esculenta. At rest, Vs of OC and SEC was virtually identical [-66.3 +/- 4.5
(SD) (n = 10) and -67.3 +/- 5.9 mV (n = 9)] and both cells responded to
increasing serosal K+ concentration from 4 to 13 mmol/l with virtually the
same depolarization (delta Vs,K) of +16.2 +/- 2.0 and +16.0 +/- 2.9 mV,
respectively, while Vt declined by approximately half as much. Histamine
(0.1 mmol/l) reduced Vt and Rt and increased the voltage divider ratio in
both cell types, indicating a fall in basolateral membrane resistance. In
the OC, this increase was neither associated with a significant alteration
of Vs nor with a change in delta Vs,K. In the SEC, however, histamine
markedly increased Vs to -75.5 +/- 7.3 mV (n = 9) as well as delta Vs,K to
+18.5 +/- 2.6 mV, which was paralleled by an increase in delta Vt,K from
9.8 +/- 3.9 to +12.8 +/- 4.2 mV. The data indicate that 1) both OC and SEC
respond to histamine, 2) both OC and SEC contain a basolateral K+
conductance that increases under histamine (in OC probably, in parallel
with other ion conductances), and 3) in Rana esculenta the SEC contribute
substantially to Vt.
