PGE1-induced intestinal secretion: mechanism of enhanced transmucosal protein efflux.

The effects of local intra-arterial prostaglandin E1 (PGE1) infusion on net transmucosal volume and protein fluxes, lymphatic volume and protein fluxes, and regional hemodynamics were ascertained in autoperfused segments of cat ileum. After acquiring control values (and tissue samples) for the various parameters, PGE1 (5.0 microgram/min) was infused directly into the superior mesenteric artery. The PGE1 infusions resulted in dramatic increases in ileal lymphatic volume and protein fluxes and blood flow. Infusion of PGE1 caused a reversion of net mucosal volume absorption to net secretion and an increased loss of plasma proteins into the lumen. Ultrastructural analysis of tissue samples taken during the PGE1 infusion indicate major structural damage to the mucosal membrane. The physiological and ultrastructural data acquired in this study suggest that 1) the increased transmucosal protein efflux during intra-arterial PGE1 infusions results from an alteration in mucosal transcapillary fluid exchange and 2) a significant portion of PGE1-induced ileal secretion is passively mediated.