Developmental changes in functional expression and β-adrenergic regulation of If in the heart of mouse embryo

Abstract

The hyperpolarization-activated current (I ƒ ) plays an important role in determining the spontaneous rate of cardiac pacemaker cells. The automatic rhythmicity also exists in working cells of embryonic heart, therefore we studied developmental changes in functional expression and β-adrenergic regulation of I ƒ in embryonic mouse heart. The expression of I ƒ is high in early developmental stage (EDS) (10.5 d after coitus) ventricular myocytes, low in intermediate developmental stage (IDS) (13.5 d) atrial or ventricular myocytes and even lower in late developmental stage (LDS) (16.5 d) atrial or ventricular myocytes, indicating that these cells of the EDS embryonic heart have some properties of pacemaker cells. β-adrenergic agonist isoproterenol (ISO) stimulates I f in LDS but not in EDS cardiomyocytes, indicating that the b-adrenergic regulation of If is not mature in EDS embryonic heart. But forskolin (a direct activator of adenylate cyclase) and 8-Br-cAMP (a membrane-permeable analogue of cAMP) increase the amplitude of I ƒ in EDS cells, indicating that adenylate cyclase and cAMP function fairly well at early stage of development. Furthermore, the results demonstrate that I ƒ is modulated by phosphorylation via cAMP dependent PKA both in EDS and LDS cells.

Functional Characterization of Inward Rectifier Potassium Ion Channel in Murine Fetal Ventricular Cardiomyocytes

“…This is the first paper that reveals the functional characterization of IK1 in murine fetal cardiomyocytes and its functional role in cardiac excitability, which clearly demonstrated the developmental changes in the IK1 subunits. The findings here may offer a new aspect for better understanding of cardiogenesis and heart disease such as myocardial hypertrophy and heart failure [20][21][22].…”

“…The embryonic cardiomyocytes display spontaneous occurring APs [18][19] and share some properties of the diseased cardiomyocytes which suffer from hypertrophy or cardiac failure [20][21][22]. Thus electrophysiological properties of fetal cardiomyocytes have recently been discussed intensively [23][24][25][26].…”

Coculture of Embryonic Ventricular Myocytes and Mouse Embryonic Stem Cell Enhance Intercellular Signaling by Upregulation of Connexin43

“…If female mice were pregnant this was recorded as E0.5, and E17.5 was used as the late embryonic development stage [18,19]. E17.5 pregnant female mice were sacrificed by cervical dislocation and the embryonic hearts were removed.…”

Molecular and Functional Changes in Voltage-Gated Na+ Channels in Cardiomyocytes During Mouse Embryogenesis

“…Briefly, after the embryos were harvested, hearts were dissected and ventricles separated from atria, single cardiomyocytes were isolated from the ventricles using enzymatic dissociation procedures as described previously. 18, 19 The isolated cells were plated onto sterile, gelatin-coated glass coverslips and kept in the incubator for 24-48 h. All procedures were performed in accordance with the Guidelines of the Hubei Council of Animal Care and approved by the Animal Use Subcommittee of Huazhong University of Science and Technology, China.…”