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Physiological modulation of protein kinase G by chronic hypoxia and maturation in adult and fetal ovine common carotid arteries
Author(s) -
Williams James Michael,
Pearce William Julian
Publication year - 2006
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.20.5.a1217-b
Subject(s) - hypoxia (environmental) , fetus , medicine , endocrinology , biology , circulatory system , phosphorylation , anatomy , chemistry , microbiology and biotechnology , oxygen , pregnancy , organic chemistry , genetics
In ovine carotid arteries, relaxation responses to 8pCPT‐cGMP, a cell permeant non‐hydrolyzable analogue of cGMP, are strongly influenced by chronic hypoxia and postnatal maturation. Thus, we hypothesized that chronic hypoxia modulates PKG activity and/or abundance in an age‐dependent manner. To test this hypothesis, we measured rates of phosphorylation of a specific PKG substrate (BPDEtide) following activation of PKG in crude high‐speed (100,000 XG) artery homogenates with 5 μM cGMP in presence of ATP[?32P] and separation on phosphocellulose. Rates of phosphorylation were significantly enhanced by hypoxia but depressed by maturation and averaged 1959±100 (normoxic adult), 2309 ± 76 (hypoxic adult), 2552±78 (normoxic fetus) and 3392 ± 149 (hypoxic fetus) pmol ATP/mg protein/min. Despite greater PKG activity in fetal than adult arteries, quantitative Western blots revealed that PKG abundances were marked greater in adult than fetal arteries under both normoxic and hypoxic conditions. Immunohistochemistry further revealed that PKG was distributed predominantly near the advential‐medial border in adult arteries, but near the basal lamina in fetal arteries. These differences suggest that PKG is physiologically upregulated by chronic hypoxia, but downregulated by postnatal maturation. Such changes have important implications for vascular regulation and reactivity to NO in fetuses born following conditions of chronic intrauterine hypoxia and/or fetal distress. Supported by NIH HD31226 and HL64867