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Age‐related phenotypic transformation alters expression of heavy myosin isoforms SM1 and SM2 in ovine cerebral arteries
Author(s) -
Pearce William Julian,
Abrassart Jenna M,
Dakanay Rina C,
Williams James M
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.625.20
Subject(s) - myosin , cerebral arteries , phenotype , vascular smooth muscle , gene isoform , biology , immunohistochemistry , fetus , lumen (anatomy) , medicine , anatomy , endocrinology , microbiology and biotechnology , smooth muscle , immunology , gene , biochemistry , pregnancy , genetics
Vascular smooth muscle cells exhibit multiple stable phenotypes, including migratory, proliferative, synthetic, and contractile. The protein markers characteristic of these phenotypes are poorly defined. The present study explores the hypothesis that the heavy myosin isoforms SM1 and SM2 are reliable indicators of the extent of differentiation and contractile maturation in ovine cerebral arteries. Arteries from normoxic and chronically hypoxic (110 d at 3820 m) term fetal and non‐pregnant adult sheep were probed with antibodies against SM1 and SM2, then analyzed via Westerns and line‐scan fluorescent microscopy to determine absolute abundance of each marker as a function of relative distance from the lumen to the adventitial‐medial border. Postnatal maturation dramatically decreased the ratio of SM1 to SM2 expression approximately 2‐fold. Hypoxic acclimatization appeared to retard the rate of contractile maturation, and enhanced the SM1/SM2 ratio. Hypoxic effects were most prominent in smooth muscle near the lumen, whereas maturational effects were more evident in peri‐adventitial smooth muscle. Thus, expression patterns of SM1 and SM2 reliably reveal the age‐dependent phenotypic status of contractile smooth muscle, and appear to be influenced by independent mitogenic factors acting at the luminal and adventitial borders of ovine cerebral arteries. Supported by USPHS Grants HD31266, & HL64867.