[Effect of serotonin on unidirectional ion fluxes in rat intestine in vivo].
OBJECTIVE
A stimulating intestinal secretory effect is described in vitro and an inhibition with selective inhibitors of the different receptors of serotonin (5-HT), in vivo. But a direct effect, in vivo, in fully vascularized and innervated intestine has not yet been clearly evidenced. We studied the effect of 5-HT in anesthetized rats with ligated loops. This work, performed at 4 intestinal levels, allowed a comparison with the effects of a known stimulant of intestinal secretion, VIP, and a specific inhibitor of Na/H exchange, dimethylamiloride (DMA).


RESULTS
5-HT induced an inhibition of epithelial Na influx in agreement with the inhibition of Na/H exchanger, an inhibition of the influx of Cl, partially passive absorption following Na by paracellular route. A decrease of Na and Cl efflux was induced by 5-HT in duodenum, jejunum and ileum while in colon, a stimulation was obtained by intraluminal but not intravenous route.


CONCLUSIONS
Even though 5-HT induced a liquid accumulation in all intestinal segments, the effect differed according to the intestinal level, either inhibition of absorption in the small intestine, or stimulation of secretion in the colon. The comparison of the effect of 5-HT with that of DMA shows that the inhibition of absorption is not only due to Na/H exchanger inhibition.
Grishina
O
O
Laboratoire du Système Neuro-Endocrine et Epithélium Intestinal Normal et Néoplasique, INSERM U45, Lyon.
Volant
K
K
Marquet
F
F
Pansu
D
D
Descroix-Vagne
M
M
D000818:Animals; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D017136:Ion Transport / Q000187:drug effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors
D017923:Sodium-Hydrogen Exchangers; D012701:Serotonin
Effet de la sérotonine sur les flux unidirectionnels des ions dans l'intestin de rat in vivo.