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Ontogenetic transition of cardiac myosin heavy chain isoforms in rat ventricle: effects of fetal exposure to beta-adrenergic agonists or antagonists.
Briggs, M M; Seidler, F J; Slotkin, T A; Schachat, F H.
Afiliação
  • Briggs MM; Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710.
J Dev Physiol ; 17(4): 201-6, 1992 Apr.
Article em En | MEDLINE | ID: mdl-1357026
Cardiac myosin heavy chain (MHC) expression undergoes an ontogenetic transition from beta to alpha MHC isoforms. Although thyroid hormone plays a role in this change, the timing of the events suggests the participation of other factors. Using a new, denaturing SDS-PAGE procedure that cleanly resolves the beta and alpha heavy chains, we have assessed the role of beta-adrenergic stimulation on this transition in fetal and neonatal rat hearts. In control animals at embryonic day 20, less than 15% of the MHC was the alpha-form, and the proportion increased to approximately 35% by postnatal day 1 and to 80% by postnatal day 8. Although catecholamine levels rise abruptly at birth, and cyclic AMP levels increase the expression of alpha-MHC in vitro, neither premature beta-adrenergic stimulation (maternal treatment with terbutaline on embryonic days 17, 18 and 19) nor continuous prenatal blockade of beta-receptors (maternal propranolol infusions from embryonic day 7 onward) influenced the developmental profile. Because beta-receptors in fetal and neonatal heart are functionally linked to adenylate cyclase, and cyclic AMP has been shown to promote the expression of alpha-MHC, the lack of effect of terbutaline or propranolol suggests that activation of adenylate cyclase through fetal cardiac beta-receptors is not sufficient to mediate the switchover without participation of other factors, such as thyroid or steroid hormones, or hypoxia.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Simpatomiméticos / Miosinas / Coração Fetal / Isoenzimas / Miocárdio Limite: Animals / Pregnancy Idioma: En Revista: J Dev Physiol Ano de publicação: 1992 Tipo de documento: Article
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Simpatomiméticos / Miosinas / Coração Fetal / Isoenzimas / Miocárdio Limite: Animals / Pregnancy Idioma: En Revista: J Dev Physiol Ano de publicação: 1992 Tipo de documento: Article