Antisecretory Activity of the Alpha 2-adrenoceptor Agonist, Xylazine in Rat Jejunal Epithelium
Overview
Authors
Affiliations
Xylazine, an alpha 2 adrenoceptor agonist, reduces short circuit current (SCC) in epithelial preparations of rat jejunum. The alpha 2 antagonist yohimbine, abolished this response while prazosin was without effect. The cyclooxygenase inhibitor, piroxicam, also attenuated xylazine responses indicating that the antisecretory effects were dependent upon endogenous eicosanoid formation. If the secretory state of piroxicam treated tissues was restored by addition of either forskolin, vasoactive intestinal polypeptide (VIP), prostaglandin E2 (PGE2) or isobutyl-1-methyl-xanthine (IBMX) then subsequent additions of xylazine were effective in reducing SCC. All these agents are known to increase SCC and cause Cl secretion by elevating intracellular cAMP. In addition, xylazine was also able to inhibit the Ca2+-mediated secretory responses of carbachol (CCh) and substance P (SP) in rat jejunum. This ability of xylazine to inhibit cAMP- and Ca2+-mediated secretion may indicate that alpha 2 adrenoceptors interact with more than one type of G protein or alternatively suggests a more general interaction between second messenger systems within epithelia of the small intestine.
Alpha(2) adrenoceptors regulate proliferation of human intestinal epithelial cells.
Schaak S, Cussac D, Cayla C, Devedjian J, Guyot R, Paris H Gut. 2000; 47(2):242-50.
PMID: 10896916 PMC: 1728001. DOI: 10.1136/gut.47.2.242.
Characterization and distribution of alpha 2-adrenergic receptors in the human intestinal mucosa.
Valet P, Senard J, Devedjian J, Planat V, Salomon R, Voisin T J Clin Invest. 1993; 91(5):2049-57.
PMID: 8098045 PMC: 288203. DOI: 10.1172/JCI116427.
The effects of capsaicin upon electrogenic ion transport in rat descending colon.
Yarrow S, Ferrar J, Cox H Naunyn Schmiedebergs Arch Pharmacol. 1991; 344(5):557-63.
PMID: 1725806 DOI: 10.1007/BF00170652.