AJP - Gastrointestinal and Liver Physiology, Vol 238, Issue 3 197-G202, Copyright © 1980 by American Physiological Society
Carbon monoxide insensitivity of gastric acid secretion
G. W. Kidder 3rd
By the use of hyperbaric conditions, it is possible to obtain high CO/O2
while maintaining O2 tension at a level that is not in itself inhibitory of
acid secretion in the isolated frog gastric mucosa. Free solution CO/O2 of
up to 10:1 only inhibit acid secretion about 20%, less than expected.
Considerations of O2 diffusion into a respiring tissue bounded by unstirred
layers predict a CO/O2 at the terminal oxidase ranging from 12 to 64 under
various conditions and positions in the tissue, with predicted inhibitions
between 55 and 86%. The inhibition observed is light reversible, affects
potential difference and resistance in a consistent manner but is never
very large. In the absence of O2, the CO-cytochrome alpha 3 complex can be
demonstrated spectrophotometrically. Among other possible explanations for
these observations, it is suggested that this tissue may contain an
inhibitor-insensitive oxidase for a portion of the cytochrome system
directly involved in acid secretion.
