Action of exendin (9-39) amide on GLP-1 (7-36) amide and exendin-4 mediated contractions of Suncus murinus (house musk shrew) isolated ileum
Author(s)
Author(s)
Rudd, J. A.
Lin, G.
He, J.
Yamamoto, K.
Date Issued
2006
Conference
15th World Congress of Pharmacology
Abstract
In the present studies, we investigated the action of glucagon-like peptide (GLP-1) agonists GLP-1 (7-36) amide and exendin-4 on the Suncus murinus isolated ileum. Segments of ileumwere placed in an organ bath containing Kreb’s solution. Agonists were added to the bath using a 2-6 min dosing schedule. GLP-1 (7-36) amide and exendin-4 (0.1-100 nM) induced concentration-dependent contractions yielding pEC50 values of 8.6 ±0.3 and 8.3 ±0.3, respectively. The GLP-1 antagonist exendin (9-39) amide (0.3-3 nM) was inactive alone, but non-competitively antagonized the action of both agonists with apparent pKB values of 9.8 and 9.7, respectively. In other experiments, tetrodotoxin (1 μM) and atropine (1 μM) significantly antagonized (p < 0.01) the contractile action of exendin-4 (10 nM), whereas hexamethonium (500 μM) had no action. In conclusion, the action of GLP-1 receptor agonists to contract the ileum probably involves the enteric nervous system and a release of acetylcholine to activate muscarinic receptors.
SFU Affiliated Publication
No
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