AJP - Cell Physiology, Vol 264, Issue 6 C1428-C1433, Copyright © 1993 by American Physiological Society
Inhibitory effect of EGF on secretory response of rat parietal cells is associated with an induction of ODC
J. Ostrowski, K. Wojciechowski, S. J. Konturek and E. Butruk
Department of Gastroenterology and Metabolism, Medical Center of Postgraduate Education, Warsaw, Poland.
The present studies were designed to evaluate the parietal cell acid
production in response to short-time stimulation by epidermal growth factor
(EGF). Studies were performed in vitro using isolated cells from rat
stomachs, and acid production was indirectly determined by [14C]aminopyrine
accumulation. EGF inhibited histamine-stimulated aminopyrine accumulation
from standard incubation medium (K+ = 5 mM) but not from that with
increased K+ concentration (K+ = 70 mM). EGF significantly stimulated
ornithine decarboxylase (ODC) activity, an effect that was blocked by the
specific ODC inhibitor, difluoromethylornithine (DFMO). In the presence of
DFMO, EGF failed to inhibit histamine-stimulated aminopyrine uptake. Like
EGF, the polyamine spermine, which is a direct product of enhanced ODC
activity, also inhibited histamine-stimulated aminopyrine uptake. Unlike
EGF, the spermine-induced inhibition of aminopyrine accumulation was not
altered by DFMO. Thus the DFMO effect was specific to EGF. Taken together,
these results are consistent with the postulate that EGF inhibits parietal
cell secretory response through the induction of ODC activity and increased
synthesis of polyamines.
