AJP - Gastrointestinal and Liver Physiology, Vol 244, Issue 2 131-G137, Copyright © 1983 by American Physiological Society
Factors influencing metabolism of arachidonic acid in guinea pig gastric mucosa
D. A. Ahlquist, T. H. Madson, J. C. Romero, R. R. Dozois and J. R. Malagelada
The metabolism of [14C]arachidonic acid in whole homogenates of gastric
corpus mucosa in the guinea pig was characterized. Identity of labeled
products was validated by comigration against standards in multiple
chromatographic systems and by selective synthesis inhibition. At
near-physiological conditions, homogenates converted arachidonic acid to
the cyclooxygenase products prostaglandins F2, E2, and D2,
6-keto-prostaglandin F1 alpha, and thromboxane B2 (in descending order of
magnitude) and to a lipoxygenase product cochromatographing with
12-hydroxyeicosatetraenoic acid. However, dramatic qualitative and
quantitative changes in this product profile were noted with relatively
small changes in incubation temperature, substrate concentration, and
especially pH. Whole homogenates generated more prostaglandin and in
different proportions than did the microsomal fraction from an equal mass
of mucosa. No catabolism of prostaglandin products was observed in whole
homogenates. Tissue preparation and storage also influenced prostaglandin
synthesis activity. These in vitro observations may have important
implications for future studies of prostaglandin generation in small
gastric mucosal biopsies.
