The permeability of the cell-to-cell membrane channel and its regulation in mammalian cell junctions

Summary Mammalian cell-to-cell channels show polar permselective properties discriminating against negatively charged 14 ?-wide molecules and are more restrictive than the channels of insect cell junctions. The channel permeability is modulated by conditions affecting the concentration of intracellular ionic Ca: elevation of the external Ca load (B cells), treatment of cell cultures with Ca-transporting ionophore (in the presence of external Ca, but not in its absence), treatment with a combination of cyanide and iodoacetate, or with high levels of carbon dioxide, all cause depression of channel permeability. Treatment of cell cultures with cyclic AMP or its more permeable derivative, dibutyryl cyclic AMP, produces increase in permeability. A similar channel up regulation is observed upon elevation of the endogenous level of cyclic AMP by serum deprivation or lowering of cell density. Presented in the symposium on Molecular and Morphological Aspects of Cell-Cell Communication at the 31st Annual Meeting of the Tissue Culture Association, St. Louis, Missouri, June 1–5, 1980. This symposium was supported in part by Contract 263-MD-025754 from the National Cancer Institute and the Fogarty International Center. This work was supported by grant number 5 R01 CA14464, awarded by the National Cancer Institute, DHEW.