title: Induction of matrix metalloproteinase-2 enhances systemic arterial contraction after hypoxia.
abstract: This study was carried out to determine the role of increased vascular matrix metalloproteinase-2 (MMP-2) expression in the changes in systemic arterial contraction after prolonged hypoxia. Rats and mice were exposed to hypoxia (10% and 8% O(2), respectively) or normoxia (21% O(2)) for 16 h, 48 h, or 7 days. Aortae and mesenteric arteries were either mounted in organ bath myographs or frozen in liquid nitrogen. MMP-2 inhibition with cyclic CTTHWGFTLC (CTT) reduced contraction to phenylephrine (PE) in aortae and mesenteric arteries from rats exposed to hypoxia for 7 days but not in vessels from normoxic rats. Similarly, CTT reduced contraction to Big endothelin-1 (Big ET-1) in aortae from rats exposed to hypoxia for 7 days. Responses to PE were reduced in hypoxic MMP-2(-/-) mice compared with MMP-2(+/+) mice. Increased contraction to Big ET-1 after hypoxia was observed in MMP-2(+/+) mice but not in MMP-2(-/-) mice. Rat aortic MMP-2 and membrane type 1 (MT1)-MMP protein levels and MMP activity were increased after 7 days of hypoxia. Rat aortic MMP-2 and MT1-MMP mRNA levels were increased in the deep medial vascular smooth muscle. We conclude that hypoxic induction of MMP-2 expression potentiates contraction in systemic conduit and resistance arteries. This may preserve the capacity to regulate the systemic circulation in the transition between the alterations in vascular tone and structural remodeling that occurs during prolonged hypoxic epochs.
authors.affiliation: Dept. of Critical Care, Rm. 4-015, St. Michael's Hospital, 30 Bond St., Toronto, ON, Canada.
authors.forename: Jeff Z
authors.initials: JZ
authors.lastname: He
authors.forename: Adrian
authors.initials: A
authors.lastname: Quan
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.forename: Hwee
authors.initials: H
authors.lastname: Teoh
authors.forename: Guilin
authors.initials: G
authors.lastname: Wang
authors.forename: Jason E
authors.initials: JE
authors.lastname: Fish
authors.forename: Brent M
authors.initials: BM
authors.lastname: Steer
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Itohara
authors.forename: Philip A
authors.initials: PA
authors.lastname: Marsden
authors.forename: Sandra T
authors.initials: ST
authors.lastname: Davidge
authors.forename: Michael E
authors.initials: ME
authors.lastname: Ward
mesh_terms: D000818:Animals; D001158:Arteries / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology*; D004789:Enzyme Activation; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: C415426:CTTHWGFTLC peptide; D010456:Peptides, Cyclic; D020778:Matrix Metalloproteinase 2