The function of prostaglandins in transmucosal water movement and blood flow in the rat jejunum

Abstract

1. Jejunal loops of anaesthetized rats were perfused with isotonic buffer containing PGE1, PGF2alpha or indomethacin. Intestinal blood flow, absorption and secretion of tritiated water were measured. 2. PGE1 at the low concentration of 0.1 microgram ml-1 did not influence intestinal blood flow but increased secretion and decreased absorption of tritiated water. In higher concentrations (0.5 and 6.5 microgram ml-1), blood flow, secretion and absorption were enhanced. 3. PGF2alpha, even in the high concentration of 50 microgram ml-1, did not influence intestinal blood flow but enhanced secretion and decreased absorption of tritiated water. 4. Indomethacin (1 microgram ml-1) decreased intestinal blood flow and secretion but enhanced absorption of tritiated water. 5. The effects of indomethacin on blood flow can be prevented and those on secretion can be even reversed by an additional infusion of PGE1 (0.5 microgram ml-1). 6. PGs appear to play a physiological role in the regulation of intestinal blood flow and transmucosal water movement, since inhibition of endogenous PG synthesis by indomethacin results in effects opposite to those of intraluminally applied PGE1. The results obtained with the low concentration of PGE1 (0.1 microgram ml-1) and with PGF2alpha (50 microgram ml-1) strongly indicate that intestinal water movement can be changed independently of intestinal blood flow.

Ricinoleate and deoxycholate are calcium ionophores in jejunal brush border vesicles

“…Ricinoleate and deoxycholate have been shown to be associated with an increase in cAMP levels [7,28], but neither compound is capable of direct activation of adenyt cyclase [16]. Ricinoteate can stimulate the release of prostaglandin E from the intestine, and this is thought to account for part of the secretory process [4,5]. Furthermore, ricinoleate has been shown to stimulate the release of arachidonic acid and its metabolites from perfused rabbit vascular tissue in a Ca 2 § manner analogous to the effects of A23187 in the same system [22].…”

SEROTONIN ‐ AN INTESTINAL SECRETAGOGUE ‐ Receptor Subtypes and Intracellular Mediators

“…In fact, PGE2 might also influence intestinal fluid transport by changing the blood flow, since PGs are also vasoactive substances, regulating blood flow in various organs. Since PGE2 levels were low M) (VI), PGE2 most likely induced the changes in transmural water movement independently of the intestinal blood flow (Beubler &Juan 1977).…”

INHIBITION BY MORPHINE OF PROSTAGLANDIN E1‐STIMULATED SECRETION AND CYCLIC ADENOSINE 3′,5′‐MONOPHOSPHATE FORMATION IN THE RAT JEJUNUM in vivo

“…Diarrhoea associated with radiotherapy is also thought to be caused by PGE release (Mennie, Dalley, Dinneen & Collier, 1975). Prostaglandins appear to play a physiological role in the regulation of intestinal blood flow and transmucosal water movement (Beubler & Juan, 1977). They are released into the gut after mechanical stimulation of the mucosa (Beubler & Juan, 1978a) and are, furthermore, considered to be implicated in the mechanism of action of non-osmotic laxatives (Beubler & Juan, 1978b, c;.…”

“…This secretory effect of theophylline is due to its ability to increase cyclic AMP levels (Powell et al, 1974) by inhibiting the phosphodiesterase which converts cyclic AMP to AMP (Butcher & Sutherland, 1962). Both theophylline and PGE1 increase intestinal blood flow (Beubler & Lembeck, 1976;Beubler & Juan, 1977), probably also as a result of the ability of both agents to increase cyclic AMP levels.…”