title: Low [Mg(2+)](o) induces contraction of cerebral arteries: roles of tyrosine and mitogen-activated protein kinases.
abstract: The present study was designed to investigate the mechanism of action of low extracellular magnesium ion concentration ([Mg(2+)](o)) on isolated canine basilar arteries and single cerebral vascular smooth muscle cells from these arteries. Low-[Mg(2+)](o) medium (0-0.6 mM) produces endothelium-independent contractions in isolated canine basilar arteries in a concentration-dependent manner; the lower the concentration of [Mg(2+)](o), the stronger the contractions. The low-[Mg(2+)](o) medium-induced contractions are significantly attenuated by pretreatment of the arteries with low concentrations of either SB-203580, U-0126, PD-98059, genistein, or an Src homology 2 (SH2) domain inhibitor peptide. IC(50) levels obtained for these five antagonists are consistent with reported inhibitor constant (K(i)) values for these tyrosine kinase and mitogen-activated protein kinase (MAPK) antagonists. Low-[Mg(2+)](o) medium (0-0.6 mM) produces transient intracellular calcium ion concentration ([Ca(2+)](i)) peaks followed by a slow, sustained, and elevated plateau of [Ca(2+)](i) in primary single smooth muscle cells from canine basilar arteries. Low-[Mg(2+)](o) medium induces rapid and stable increases in [Ca(2+)](i); these increases are inhibited markedly in the presence of either SB-203580, U-0126, PD-98059, genistein or a SH2 domain inhibitor peptide. Several specific antagonists of known endogenously formed vasoconstrictors do not inhibit or attenuate either the low-[Mg(2+)](o)-induced contractions or the elevation of [Ca(2+)](i). The present study suggests that activation of several cellular signaling pathways, such as protein tyrosine kinases (including the Src family) and MAPK, appears to play important roles in low-[Mg(2+)](o)-induced contractions and the elevation of [Ca(2+)](i) in smooth muscle cells from canine basilar arteries.
authors.affiliation: Department of Physiology and Pharmacology, State University of New York Health Science Center at Brooklyn, Brooklyn, New York 11203, USA.
authors.forename: Z W
authors.initials: ZW
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Zheng
authors.forename: B T
authors.initials: BT
authors.lastname: Altura
authors.forename: B M
authors.initials: BM
authors.lastname: Altura
mesh_terms: D000818:Animals; D001488:Basilar Artery / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D002070:Butadienes / Q000494:pharmacology; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology* / Q000502:physiology; D008275:Magnesium Deficiency / Q000503:physiopathology*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D010748:Phosphopeptides / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D009570:Nitriles; D010748:Phosphopeptides; D011725:Pyridines; C113580:U 0126; C404208:acetyl-phosphotyrosyl-phosphotyrosyl-phosphotyrosyl-isoleucyl-glutamic acid; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases; D008274:Magnesium; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one