Prostaglandin synthesis by microsomes of circular and longitudinal gastrointestinal muscles

Abstract

Experiments were performed to determine whether longitudinal and circular muscles from various regions of [dog] stomach and small bowel had the capacity to convert arachidonic acid (AA) to prostaglandins (PG). PG production by the microsomal fractions of isolated muscles was assayed by determining the conversion of [14C]AA to 14C-labeled 6-keto-PGF1.alpha., PGF2.alpha., PGE2, PGD2, PGA2 and thromboxane B2. Individual PG were identified by TLC. The metabolism of [14C]AA to [14C]PG was linearly related to substrate concentration, enzyme concentration and incubation time at 37.degree. C and was inhibited in a dose-dependent manner by indomethacin. Longitudinal and circular muscles from all tested regions (corpus, fundus, antrum, pylorus, duodenum, jejunum and ileum) synthesized PG. In all regions the major end products of AA metabolism were 6-keto-PGF1.alpha., PGE2 and PGF2.alpha.. Circular and longitudinal muscles from all regions of the stomach and small bowel contain the enzymatic apparatus necessary to convert AA into prostaglandins.