Characterisation of Connexin Expression and Electrophysiological Properties in Stable Clones of the HL-1 Myocyte Cell Line

Abstract

The HL-1 atrial line contains cells blocked at various developmental stages. To obtain homogeneous sub-clones and correlate changes in gene expression with functional alterations, individual clones were obtained and characterised for parameters involved in conduction and excitation-contraction coupling. Northern blots for mRNAs coding for connexins 40, 43 and 45 and calcium handling proteins (sodium/calcium exchanger, L- and T-type calcium channels, ryanodine receptor 2 and sarco-endoplasmic reticulum calcium ATPase 2) were performed. Connexin expression was further characterised by western blots and immunofluorescence. Inward currents were characterised by voltage clamp and conduction velocities measured using microelectrode arrays. The HL-1 clones had similar sodium and calcium inward currents with the exception of clone 2 which had a significantly smaller calcium current density. All the clones displayed homogenous propagation of electrical activity across the monolayer correlating with the levels of connexin expression. Conduction velocities were also more sensitive to inhibition of junctional coupling by carbenoxolone (∼80%) compared to inhibition of the sodium current by lidocaine (∼20%). Electrical coupling by gap junctions was the major determinant of conduction velocities in HL-1 cell lines. In summary we have isolated homogenous and stable HL-1 clones that display characteristics distinct from the heterogeneous properties of the original cell line.

Functional Characterization of a Novel Truncating Mutation in Lamin A/C Gene in a Family with a Severe Cardiomyopathy with Conduction Defects

“…The electrical activity of cardiomyocytes creating a functional syncytium is synchronized and driven by the cells that have the fastest frequency of generation of spontaneous action potentials. Under this scenario, electrical coupling by gap junctions is the key determinant of conduction velocities in HL-1 cardiomyocytes [27]. In fact, when we recorded the spontaneous Ca 2+ oscillations in 4 cells of the same functional syncytium we found the same pattern of Fig.…”

Electroactive polyurethane/siloxane derived from castor oil as a versatile cardiac patch, part II: HL‐1 cytocompatibility and electrical characterizations

“…Our investigations showed that the as prepared electroactive substrate possess the ability to carry bioelectricity. It was found that the electroactive XSi‐PU3 is not only biocompatible in terms of cellular toxicity but (i) do not alter the intrinsic electrical characteristics of HL‐1 cells and (ii) is capable to conduct bioelectricity from two separated clusters (i.e., ca. 1 mm in Fig.…”

Functional Characterization and Comparison of Intercellular Communication in Stem Cell-Derived Cardiomyocytes

“…B). While neonatal CMs show a fast increase in fluorescence in the neighbored cell, dye transfer was significantly slower in both SC‐CMs and HL‐1 cells, the latter being known for relatively low connectivity . Curves were fitted with a sigmoidal function according to the expected temporal kinetics of particle diffusion between two compartments (see below).…”