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Dilatation and constriction of rat gastric mucosal microvessels through prostaglandin EP 2 and EP 3 receptors
Author(s) -
Takashi Ohno,
Makoto Katori,
Masataka Murakami,
Takao Saeki,
Katsuharu Boku,
Kazuo Nishiyama,
Hiromi Hayashi,
Katsunori Saigenji
Publication year - 1999
Publication title -
alimentary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.308
H-Index - 177
eISSN - 1365-2036
pISSN - 0269-2813
DOI - 10.1046/j.1365-2036.1999.00577.x
Subject(s) - prostaglandin e2 receptor , agonist , receptor , endocrinology , medicine , prostaglandin , microcirculation , prostaglandin e2 , misoprostol , prostanoid , gastric mucosa , stomach , biology , pregnancy , abortion , genetics
Background : Prostaglandin (PG)E 2 has both a vasodilating action and a protective function in the gastric mucosa. There are four subtypes of PGE 2 ‐sensitive, or EP, receptors. Aim : To identify the subtype of EP receptors in the microvessels of the rat gastric mucosa using EP 2 and EP 3 receptor agonists. Methods : The posterior wall of the anaesthetized rat stomach was secured in a chamber and superfused with Tyrode’s solution, and the gastric microcirculation of the mucosal base was observed through a window with transillumination. PGE 2 and its derivatives (20 μ L) were applied topically in the window. Results : PGE 2 (0.001–10 μ mol/L), misoprostol (EP 2 /EP 3 receptor agonist; 0.01–100 μ mol/L) and butaprost (EP 2 receptor agonist; 1–1000 μ mol/L) dilated the arterioles dose‐dependently, but M&B 28 767 (EP 3 receptor agonist; 0.001–10 μ mol/L) did not alter their diameters. M&B 28 767 constricted the venules and collecting venules dose‐dependently whereas butaprost dilated them. PGE 2 and misoprostol had bell‐shaped dose–response curves: constriction by low doses of PGE 2 and misoprostol (0.001–0.1 μ mol/L and 0.01–1 μ mol/L) and dilation by high doses of PGE 2 and misoprostol (0.1–100 μ mol/L and 1–100 μ mol/L). Conclusions : These results suggest that PGE 2 dilated both arterioles and venules in the rat gastric mucosa through the EP 2 receptors and constricted the venules through the EP 3 receptors.