AJP - Gastrointestinal and Liver Physiology, Vol 252, Issue 1 28-G32, Copyright © 1987 by American Physiological Society
Ontogeny of rat gastric H+-K+-ATPase activity
F. Hervatin, E. Moreau, R. Ducroc, B. Garzon, P. Avril, P. Millet and J. P. Geloso
Gastric H+-K+-ATPase activity was examined in subcellular fractions (P1,
1,000 g; P2, 20,000 g; P3, 100,000 g) obtained from fundic mucosae of
fetal, newborn, and adult rats. Depending on the tissue secretory state the
distribution of this enzyme activity predominates in P3, i.e., resting
adult, or in P2, i.e., stimulated adult, while total enzyme activity (P2 +
P3) remains constant. Enzyme activity was detected as soon as day 19 of
gestation and P2 + P3 reached 2.2 +/- 0.2 mumol Pi X mg prot-1 X h-1 at
parturition. H+-K+-ATPase activity steadily decreased from 4.0 +/- 0.7
mumol Pi X mg prot-1 X h-1 on day 6 after birth to approximately 0 on day
12. This activity recovered as soon as day 13 (3.5 +/- 0.6 mumol Pi X mg
prot-1 X h-1) and continued to rise slowly until adulthood. Incubation of
subcellular fractions with 0.1 mM omeprazole resulted in a total loss of
H+-K+-ATPase activity at all the stages of development examined. These
studies of functional relationship during the development between gastric
acid secretion and distribution of gastric H+-K+-ATPase activity among P2
and P3 fractions indicate that this last could be considered as an index of
the secretory state of the parietal cell. This enzyme's pattern of
development in P2 + P3, correlated with the one previously observed for
stimulated H+ secretion in intact tissue, suggest that the H+-K+-ATPase is
the limiting step in response to secretagogues during postnatal period.
