Prostaglandin E(2) increases cyclic AMP and inhibits endothelin-1 production/secretion by guinea-pig tracheal epithelial cells through EP(4) receptors.
Prostaglandin E(2) (PGE(2)) increased adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation in tracheal epithelial cells and concomitantly decreased the production/secretion of immunoreactive endothelin (irET). Naturally occurring prostanoids and selective and non-selective EP receptor agonists showed the following rank order of potency in stimulating cyclic AMP generation by epithelial cells: PGE(2) (EP-selective)>16,16-dimethyl PGE(2) (EP-selective)>11-deoxy PGE(2) (EP-selective)>>>iloprost (IP/EP(1)/EP(3)-selective), butaprost (EP(2)-selective), PGD(2) (DP-selective), PGF(2alpha) (FP-selective). The lack of responsiveness of the latter prostanoids indicated that the prostanoid receptor present in these cells is not of the DP, FP, IP, EP(1), EP(2) or EP(3) subtype. Pre-incubating the cells with the selective TP/EP(4)-receptor antagonists AH23848B and AH22921X antagonized the PGE(2)-evoked cyclic AMP generation. This suggested that EP(4) receptors mediate PGE(2) effects. However, in addition to any antagonistic effects at EP(4)-receptors, both compounds, to a different extent, modified cyclic AMP metabolism. The selective EP(1), DP and EP(2) receptor antagonist (AH6809) failed to inhibit PGE(2)-evoked cyclic AMP generation which confirmed that the EP(2) receptor subtype did not contribute to the change in cyclic AMP formation in these cells. The PGE(2)-induced inhibition of irET production by guinea-pig tracheal epithelial cells was due to cyclic AMP generation and activation of the cyclic AMP-dependent protein kinase since this effect was reverted by the cyclic AMP antagonist Rp-cAMPS. These results provide the first evidence supporting the existence of a functional prostaglandin E(2) receptor that shares the pharmacological features of the EP(4)-receptor subtype in guinea-pig tracheal epithelial cells. These receptors modulate cyclic AMP formation as well as ET-1 production/secretion in these cells.
Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, Canada, J1H 5N4.
S
S
Pelletier
J
J
Dubé
A
A
Villeneuve
F
F
Gobeil
Q
Q
Yang
B
B
Battistini
G
G
Guillemette
P
P
Sirois
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006168:Guinea Pigs; D008297:Male; D018078:Receptors, Prostaglandin E / Q000187:drug effects* / Q000378:metabolism; D058309:Receptors, Prostaglandin E, EP4 Subtype; D014132:Trachea / Q000187:drug effects / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology
D019332:Endothelin-1; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; D014665:Vasodilator Agents; D000242:Cyclic AMP; D000241:Adenosine; D015232:Dinoprostone