title: Modulation of junctional permeability.
abstract: Changes in intercellular coupling can be accomplished by continuous synthesis and destruction of intercellular channels and through a modulation of unit channel permeability. The increase in free [Ca2+]i caused by activation of sodium-calcium exchange or by metabolic inhibition leads to cell decoupling. In embryonic cells the conductance of the gap junction is strongly dependent on pHi. The exact role of Ca2+ and H+ in the physiological modulation of junctional conductance remains unknown. The cyclic AMP (cAMP)-calcium hypothesis is presented. According to this view, cAMP modulates the junctional permeability through specific kinases. A feedback mechanism between calcium and cAMP might be relevant in the physiological control of junctional conductance.
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D000242:Cyclic AMP / Q000502:physiology; D004553:Electric Conductivity; D006329:Heart Conduction System / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007365:Intercellular Junctions / Q000187:drug effects / Q000502:physiology*; D011690:Purkinje Fibers / Q000502:physiology*
chemical_list: D003994:Bucladesine; D000242:Cyclic AMP; D002118:Calcium