title: Open ion channels behave as simple size-selective filters bearing fixed counter-ions.
mesh_terms: D000818:Animals; D001001:Anura; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D066298:In Vitro Techniques; D007473:Ion Channels / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D007473:Ion Channels