Regional biosynthesis of prostaglandins and hydroxyeicosatetraenoic acids from arachidonic acid in the rat stomach tissue.

The present study was conducted to determine regional differences in the biosynthesis of prostaglandins (PGs) and hydroxyeicosatetraenoic acids (HETEs) in the rat stomach tissue (fundus, corpus and pyloric antrum) from radioactive arachidonic acid (AA). The radioactive metabolites were validated by RP-HPLC using non-radioactive AA as substrate. PGE(2) was the major prostanoid in the tissue(.) The relative ratio of PGE(2):PGF(2)alpha:PGD(2) in the whole stomach was 1:0.5:0.1. Regionally, the fundus biosynthesized the largest amount of all three cyclo-oxygenase products. Among the lipoxygenase metabolites, 15S-HETE was the predominant product, while 12S-HETE was found to be the lowest. The relative ratio of 15S-HETE:5S-HETE:12S-HETE in the whole stomach was 1:0.6:0.4. Interestingly, the generation of lipoxygenase products was the highest in the pyloric antrum when compared to fundus or corpus. Thus, the regional differences in the biosyntheses of gastric PGs and monohydroxy fatty acids may be relevant to our understanding of corresponding differences in mucosal resistance or susceptibility to gastric disease.