In vitro reestablishment of cell-cell contacts in adult rat cardiomyocytes. Functional role of transmembrane components in the formation of new intercalated disk-like cell contacts

Primary adult rat cardiomyocytes (ARC) in culture are shown to be a model s ystem for cardiac cell hypertrophy in vitro, ARC undergo a process of morph ological transformation and grow only by increase in cell size, however, wi thout loss of the cardiac phenotype, The isolated cells spread and establis h new cell-cell contacts, eventually forming a two-dimensional heart tissue -like synchronously beating cell, sheet. The reformation of specific cell c ontacts (intercalated disks) is shown also between ventricular and atrial c ardiomyocytes by using antibodies against the gap junction protein connexin -43 and after microinjection into ARC of N-cadherin cDNA fused to reporter green fluorescent protein (GFP) cDNA. The expressed fusion protein allowed the study of live cell cultures and of the dynamics of the adherens junctio n protein N-cadherin during the formation of new cell-cell contacts. The po ssible use of the formed ARC cell-sheet cells under microgravity conditions as a test system for the reformation of the cytoskeleton of heart muscle c ells is proposed.