Chronic hypoxia and VEGF differentially modulate abundance and organization of myosin heavy chain isoforms in fetal and adult ovine arteries

Chronic hypoxia increases vascular endothelial growth factor (VEGF) and thereby promotes angiogenesis. The present study explores the hypothesis that hypoxic increases in VEGF also remodel artery wall structure and contractility through phenotypic transformation of smooth muscle. Pregnant and nonpre...

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Published in:American Journal of Physiology: Cell Physiology 2012-11, Vol.303 (10), p.C1090-C1103
Main Authors: Hubbell, Margaret C, Semotiuk, Andrew J, Thorpe, Richard B, Adeoye, Olayemi O, Butler, Stacy M, Williams, James M, Khorram, Omid, Pearce, William J
Format: Article
Language:English
Subjects:
Angiogenesis
Animals
Arteries - embryology
Arteries - metabolism
Female
Fetus - blood supply
Genotype & phenotype
Hypoxia
Hypoxia - physiopathology
Myosin Heavy Chains - genetics
Myosin Heavy Chains - metabolism
Oxygen - metabolism
Phthalazines - pharmacology
Pregnancy
Protein Kinase Inhibitors - pharmacology
Protein Transport
Pyridines - pharmacology
Receptors, Vascular Endothelial Growth Factor - antagonists & inhibitors
Sheep
Sheep - embryology
Sheep - physiology
T cell receptors
Vascular endothelial growth factor
Vascular Endothelial Growth Factor A - pharmacology
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Summary:Chronic hypoxia increases vascular endothelial growth factor (VEGF) and thereby promotes angiogenesis. The present study explores the hypothesis that hypoxic increases in VEGF also remodel artery wall structure and contractility through phenotypic transformation of smooth muscle. Pregnant and nonpregnant ewes were maintained at sea level (normoxia) or 3,820 m (hypoxia) for the final 110 days of gestation. Common carotid arteries harvested from term fetal lambs and nonpregnant adults were denuded of endothelium and studied in vitro. Stretch-dependent contractile stresses were 32 and 77% of normoxic values in hypoxic fetal and adult arteries. Hypoxic hypocontractility was coupled with increased abundance of nonmuscle myosin heavy chain (NM-MHC) in fetal (+37%) and adult (+119%) arteries. Conversely, hypoxia decreased smooth muscle MHC (SM-MHC) abundance by 40% in fetal arteries but increased it 123% in adult arteries. Hypoxia decreased colocalization of NM-MHC with smooth muscle α-actin (SM-αA) in fetal arteries and decreased colocalization of SM-MHC with SM-αA in adult arteries. Organ culture with physiological concentrations (3 ng/ml) of VEGF-A(165) similarly depressed stretch-dependent stresses to 37 and 49% of control fetal and adult values. The VEGF receptor antagonist vatalanib ablated VEGF's effects in adult but not fetal arteries, suggesting age-dependent VEGF receptor signaling. VEGF replicated hypoxic decreases in colocalization of NM-MHC with SM-αA in fetal arteries and decreases in colocalization of SM-MHC with SM-αA in adult arteries. These results suggest that hypoxic increases in VEGF not only promote angiogenesis but may also help mediate hypoxic arterial remodeling through age-dependent changes in smooth muscle phenotype and contractility.
ISSN:0363-6143
1522-1563
DOI:10.1152/ajpcell.00408.2011