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Role of Rho‐Kinase Activity and Expression in the Ductus Arteriosus in the Chicken Embryo
Author(s) -
Cadar Adrian G,
Sirsat Tushar S,
Dzialowski Edward M
Publication year - 2010
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.24.1_supplement.lb575
Subject(s) - rhoa , hyperoxia , rho associated protein kinase , myosin light chain kinase , incubation , myosin , biology , embryo , hypoxia (environmental) , rho kinase inhibitor , contraction (grammar) , protein kinase a , ductus arteriosus , endocrinology , andrology , kinase , medicine , microbiology and biotechnology , signal transduction , chemistry , biochemistry , oxygen , organic chemistry , lung
Incubation O 2 levels have significant effects on the O 2 ‐induced contraction of the chicken ductus arteriosus (DA) and its eventual closure. Incubation in hyperoxia speeds up closure while hypoxic incubation delays closure of the chicken ductus arteriosus. We hypothesized that one mechanism for this may be timing differences in the maturation of the Rho‐kinase pathway involved in calcium sensitization and myosin light chain phosphatase inhibition. To examine this, embryos were incubated in hypoxia (15%O 2 ), normoxia (21%O 2 ) and hyperoxia (30%O 2 ) and used on embryonic day 18 and as internally and externally pipped embryos. The role of Rho‐kinase in O 2 ‐induced contraction was measured by pre‐contracting the vessel with O 2 and then exposing vessels to step‐wise increase in the Rho‐kinase inhibitor Y‐27632. On day 18 of incubation, Y‐27632 relaxed the O 2 −induced DA significantly more in hyperoxia than normoxia or hypoxia suggesting that Rho‐kinase activity increases earlier in the DA from hyperoxic incubated embryos. To examine changes in DA gene expression within the pathway, RhoA mRNA levels from hypoxic, normoxic and hyperoxic embryos was measured using rtPCR. Preliminary data suggest that incubation in chronic hyperoxia increases RhoA mRNA levels. Taken together with the in vitro contractile response to Y‐27632 this suggests that development in high O 2 up regulates RhoA gene expression. Development in a hyperoxic environment speeds up the maturation of the Rho kinase pathway in the chicken DA. This work was funded by the American Heart Association South Central Affiliate.