The cellular ionic environment regulated by various ion channels/transporters is one of the important factors for the maintenance of our normal body function.My plenary lecture will give the audience ideas on how cellular ionic environments with regard to cytosolic Cl-and interstitial H+concentrations regulate our body function.1)Cl-is the major anion in the body fluid including the intracellular fluid,however little information is available on roles of Cl-on cell and body function.