title: Mechanism of human urotensin II-induced contraction in rat aorta.
abstract: Urotensin II induced sustained contraction with an EC(50) value of 2.29 +/- 0.12 nM in rat aorta. Urotensin II (100 nM) transiently increased cytosolic Ca(2+) level ([Ca(2+)](i)), followed by a small sustained phase superimposed with rhythmic oscillatory change. In the presence of verapamil and La(3+), the [Ca(2+)](i) oscillation was completely inhibited, although a small transient increase in [Ca(2+)](i) remained. The urotensin II-induced contraction was also partially inhibited by verapamil and La(3+). Combined application of verapamil, La(3+), and thapsigargin completely inhibited the increase in [Ca(2+)](i) with only partial inhibition of the contraction elicited by urotensin II. Urotensin II increased myosin light chain (MLC) phosphorylation to a level greater than that induced by 72.7 mM KCl (high K(+)). Pretreatment with Go6983 (PKC inhibitor), U0126 (MEK inhibitor), or SB203580 (p38MARK inhibitor) partially inhibited the urotensin II-induced contraction with no effects on the high K(+)-induced contractions. Wortmannin (MLC kinase inhibitor) only partially inhibited urotensin II-induced contraction, although it completely inhibited the high K(+)-induced contraction. These results suggest that urotensin II-induced contraction is mediated by the Ca(2+)/calmodulin/MLC kinase system and modulated by the Ca(2+) sensitization mechanisms to increase MLC phosphorylation. In addition, activations of PKC, p38MAPK, and ERK1/2 modulate the contractility mediated by urotensin II in rat aorta.
authors.affiliation: Department of Hygiene & Preventive Medicine, School of Medicine, Yamagata University, Yamagata, Japan.
authors.forename: Katsunari
authors.initials: K
authors.lastname: Tasaki
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ozaki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Karaki
authors.forename: Ichiro
authors.initials: I
authors.lastname: Wakabayashi
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D002070:Butadienes / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology; D004347:Drug Interactions; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007211:Indoles; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D008301:Maleimides; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects*; D018994:Myosin Light Chains / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019284:Thapsigargin / Q000494:pharmacology; D014579:Urotensins / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C465664:2-(1-(3-dimethylaminopropyl)-5-methoxyindol-3-yl)-3-(1H-indol-3-yl)maleimide; D000730:Androstadienes; D002070:Butadienes; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007211:Indoles; D008301:Maleimides; D018994:Myosin Light Chains; D009570:Nitriles; D011725:Pyridines; C113580:U 0126; D014579:Urotensins; D011189:Potassium Chloride; D019284:Thapsigargin; D007811:Lanthanum; C029677:urotensin II; D014700:Verapamil; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C093642:SB 203580; D002118:Calcium; D000077191:Wortmannin