AJP - Gastrointestinal and Liver Physiology, Vol 240, Issue 3 206-G210, Copyright © 1981 by American Physiological Society
Acid secretion in fetal rat stomach in vitro
R. Ducroc, J. F. Desjeux, B. Garzon, J. P. Onolfo and J. P. Geloso
In vivo fetal rat stomach produces HCl 48 h before birth. This study
examines the mechanisms of H+ secretion from days 19 to 21 before birth.
Isolated fetal stomachs were mounted as flat sheets in Ussing chambers for
measurement of the transepithelial H+ fluxes (JH+) and short-circuit
current (Isc), as indexes of the active ionic fluxes, and for measurement
of total ionic conductance (G) and unidirectional mannitol fluxes from
serosa to mucosa (JMans leads to m), as indexes of passive permeability.
The results indicate that JH+ was absent at day 19 but reached 0.75 +/- 0.1
and 0.75 +/- 0.09 mueq . h-1 . cm-2 at days 20 and 21, respectively.
Concomitantly, Isc increased significantly (56%) between days 19 and 20 in
the direction of anion secretion or cation absorption. Parallel reductions
in G (45%) and in JMans leads to m (66%) were observed between days 19 and
20. In conclusion, the simultaneous appearance of active H+ secretion and
decreased passive transepithelial permeability strongly suggests that both
processes are involved in the mechanism of acidification of the fetal rat
stomach before birth.
