Alpha 2-adrenergic receptor in intestinal epithelial cells. Identification by [3H]yohimbine and failure to inhibit cyclic AMP accumulation
Nakaki, T.; Nakadate, T.; Yamamoto, S.; Kato, R.
Molecular Pharmacology 23(1): 228-234
1983
ISSN/ISBN: 0026-895X PMID: 6135143 Document Number: 220125
.alpha.2-Adrenergic receptors in isolated rat intestinal epithelial cells were identified by using the .alpha.2-selective antagonist yohimbine binding by .alpha.2-adrenergic agonists were correlated with those of the same agents for antidiarrheal effects in vivo. Clonidine (1 .mu.M) failed to reduce the cAMP levels augmented by prostaglandin E1 (PGE1) (30 .mu.M) or vasoactive intestinal peptide in the presence of 3-isobutyl-1-methyl-xanthine in these isolated cells. Epinephrine (10 .mu.M) in the absence or presence of pindolol (10 .mu.M) did not reduce the PGE1-augmented cAMP levels. The intestinal epithelial cells evidently contain .alpha.2-adrenergic receptors through which .alpha.2-adrenergic agonists may exert their antidiarrheal effect. The antidiarrheal effect of .alpha.2-adrenergic agonists may not be due to the inhibition of adenylate cyclase in these cells.