AJP - Gastrointestinal and Liver Physiology, Vol 254, Issue 3 399-G407, Copyright © 1988 by American Physiological Society
Function and structure of parietal cells after H+-K+-ATPase blockade
J. Fryklund, H. F. Helander, B. Elander and B. Wallmark
Hassle Gastrointestinal Research Laboratories, Department of Biology, Molndal, Sweden.
Omeprazole was administered to rabbits as a single dose or daily for 1 wk.
H+-K+-ATPase and isolated gastric glands were prepared from the oxyntic
corpus mucosa and used for functional and quantitative morphological
studies. Both 10 and 100 mumol omeprazole/kg increased the pH of the
gastric content when measured at death. The stimulated oxygen uptake and
the rate of aminopyrine (AP) uptake were both inhibited in the isolated
gastric gland preparations. Morphometric studies of biopsy specimens taken
from the corpus mucosa and isolated gastric glands showed that omeprazole
treatment increased the volume density of the acid compartments. This
expansion provides an increased accumulation space for AP. Therefore, an
increased AP uptake might be seen in glands isolated from
omeprazole-treated animals. Blockade of the H2-receptor by ranitidine
transformed the morphology of the cell into a more resting type and,
furthermore, reduced the omeprazole-induced increase in the volume density
of the acid compartments in the parietal cell. The H+-K+-ATPase activity
measured in membrane fractions from the omeprazole-treated animals was
decreased dose dependently and inhibited by 95% after 100 mumol
omeprazole/kg. However, the concentration of the enzyme in these fractions
did not change. These results indicate a specific inhibitory action of
omeprazole on the H+-K+-ATPase.
