Elevated PGI2 and PGE2 production in the rat ileum following mild hypotension.

Ileal prostaglandin (PGs) biosynthesis was compared in female rats in normal mild hemorrhage (exposed to mild hypotension, reperfusion, and maintenance on hyperalimentation for 5 days) and control groups (instrumentation and hyperalimentation without hemorrhage). Tissue PG levels were analyzed by radiochromatographic analysis of microsomal membrane fractions prepared from the ileum in each group. Total cyclooxygenase activity in the normal and control groups was modest, with low levels of 6-keto-PGF1 alpha, PGE2, PGF2 alpha, thromboxane B2, PGA2, and PGD2 being produced. Hemorrhage, reperfusion, and maintenance on hyperalimentation for 5 days markedly induced total cyclooxygenase activity in the female rat ileum. Ileal microsomal membrane fractions obtained from the mild hemorrhage group synthesized levels of individual PGs three- to seven-fold higher than the normal or control groups, with 6-keto- PGF1 alpha (breakdown product of prostacyclin), PGE2, and PGA2 demonstrating the highest levels of biosynthesis. These data suggest that the gastrointestinal tract could serve as a source for the elevated PGs known to occur in various shock models.