title: Involvement of NO and MEK/ERK pathway in enhancement of endothelin-1-induced mesenteric artery contraction in later-stage type 2 diabetic Goto-Kakizaki rat.
abstract: Endothelin (ET)-1 is a likely candidate for a key role in diabetic vascular complications. However, no abnormalities in the vascular responsiveness to ET-1 have been identified in the chronic stage of type 2 diabetes. Our goal was to look for abnormalities in the roles played by ET receptors (ET(A) and ET(B)) in the mesenteric artery of the type 2 diabetic Goto-Kakizaki (GK) rat and to identify the molecular mechanisms involved. Using mesenteric arteries from later-stage (32-38 wk old) individuals, we compared the ET-1-induced contraction and the relaxation induced by the selective ET(B) receptor agonist IRL1620 between GK rats and control Wistar rats. Mesenteric artery ERK activity and the protein expressions for ET receptors and MEK were also measured. In GK rats (vs. age-matched Wistar rats), we found as follows. 1) The ET-1-induced contraction was greater and was attenuated by BQ-123 (ET(A) antagonist) but not by BQ-788 (ET(B) antagonist). In the controls, BQ-788 augmented this contraction. 2) Both the relaxation and nitric oxide (NO) production induced by IRL1620 were reduced. 3) ET-1-induced contraction was enhanced by N(G)-nitro-l-arginine (l-NNA; NO synthase inhibitor) but suppressed by sodium nitroprusside (NO donor). 4) The enhanced ET-1-induced contraction was reduced by MEK/ERK pathway inhibitors (PD-98059 or U0126). 5) ET-1-stimulated ERK activation was increased, as were the ET(A) and MEK1/2 protein expressions. 6) Mesenteric ET-1 content was increased. These results suggest that upregulation of ET(A), a defect in ET(B)-mediated NO signaling, and activation of the MEK/ERK pathway together represent a likely mechanism mediating the hyperreactivity to ET-1 examined in this study.
authors.affiliation: Dept. of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi Univ., Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Keiko
authors.initials: K
authors.lastname: Ishida
authors.forename: Naoaki
authors.initials: N
authors.lastname: Nakayama
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Katsuo
authors.initials: K
authors.lastname: Kamata
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000201:enzymology / Q000503:physiopathology; D003925:Diabetic Angiopathies / Q000201:enzymology / Q000209:etiology* / Q000503:physiopathology; D004195:Disease Models, Animal; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000378:metabolism*; D016232:Endothelins / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation
chemical_list: D002070:Butadienes; D019332:Endothelin-1; D016232:Endothelins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D020030:Nitric Oxide Donors; D009570:Nitriles; D009842:Oligopeptides; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; C113580:U 0126; D000804:Angiotensin II; D001127:Arginine Vasopressin; C074308:sovateltide; D009599:Nitroprusside; D019335:Nitroarginine; D009569:Nitric Oxide; C086539:BQ 788; D019001:Nitric Oxide Synthase; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; C072247:cyclo(Trp-Asp-Pro-Val-Leu); C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one