Prostaglandin generation from gastroduodenal mucosa: regional and species differences.

Regional and species differences in prostaglandin synthesis from gastroduodenal mucosa were assessed radiometrically. In the presence of excess added arachidonic acid substrate, corporal mucosa generated more prostanoid product per DNA than did antral or duodenal mucosa whether the whole homogenate or the microsomal fraction was used as an enzyme source. This appeared to be secondary to variability in cyclooxygenase activity and could not be explained by regional differences in the activity of enzymes competing for arachidonic acid substrate, in free endogenous arachidonic acid levels, in prostaglandin catabolizing activity, or in homogenate inhibitors. The qualitative product profile differed between species but not between regions within a species.