AJP - Gastrointestinal and Liver Physiology, Vol 242, Issue 2 111-G115, Copyright © 1982 by American Physiological Society
Biphasic development of pentagastrin sensitivity in rat stomach
B. Garzon, R. Ducroc, J. P. Onolfo, J. F. Desjeux and J. P. Geloso
Rat stomach sensitivity to pentagastrin was examined in fetal (days 19--21)
and newborn (5--day-old) preparations in vivo and in vitro. Gastric
acidification in vivo was expressed as the gastric content pH and in vitro
as the net transepithelial H+ fluxes determined in an Ussing chamber. In
both preparations, fetal stomach first responded to pentagastrin on day 20.
Dose-dependent H+ secretion was demonstrated in vitro for pentagastrin
concentrations of 10(-8) to 10(-6) M, with half-maximal stimulations at 1.9
x 10(-7) and 4 x 10(-7) M on days 20 and 21, respectively. In contrast,
isolated fundic mucosa of 5-day-old rat pups exhibited very low H+
secretion rates, and pentagastrin did not significantly stimulate acid
output. Fetal serum immunoreactive gastrin was detected as early as day 16
in fairly constant concentrations (about 77.5 pg eq synthetic human
gastrin/ml). These results indicate that, although immunoreactive gastrin
is present in serum as early as day 165, pentagastrin does nt stimulate
acid secretion until day 20 when fetal stomach exhibits active H+ secretion
and decreased passive permeability. Pentagastrin sensitivity disappears
during the 1st days of extrauterine life. These findings strongly suggest
that the development of pentagastrin sensitivity in rat stomach is
biphasic.
