Differential regional changes of prostacyclin and thromboxane A2 synthesis in the intestinal tract of the fasted and semistarved rat.

The synthesis of prostacyclin (PGI2) and thromboxane A2 (TXA2) by the mucosal and muscular portions of the duodenum, jejunum, ileum and ascending colon, as well as that by mesenteric vessels, was investigated in starved and semistarved rats. The jejunal mucosa and muscularis showed a marked increase in PGI2 synthesis after fasting for 48 h and 72 h or semistarvation for 9 days when compared with controls. Jejunal TXA2 synthesis did not alter. In contrast, PGI2 and TXA2 synthesis in ileal mucosa and muscularis was significantly reduced after fasting for 48 h, 72 h and semistarvation for 9 days. PGI2 and TXA2 synthesis by duodenal and colonic muscularis was unaffected by fasting or semistarvation. PGI2 synthesis in mesenteric vessels was significantly increased by fasting and semistarvation. No changes in PGI2 or TXA2 were detected at 24 h in fasted rats in any of the tissues studied when compared with controls. These selective changes in PGI2/TXA2 secretion may be important mediators of adaptive changes in the small intestine in response to starvation.