title: Different permeability of potassium salts across the blood-brain barrier follows the Hofmeister series.
abstract: The passage of ions across biological membranes is regulated by passive and active mechanisms. Passive ion diffusion into organs depends on the ion-pairing properties of salts present in the serum. Potassium ions could affect brain activity by crossing the blood-brain barrier (BBB) and its accumulation in the extracellular cerebral space could precipitate seizures. In the present study, we analyze passive diffusion of a series of potassium salts in the in vitro isolated guinea pig brain preparation. Different potassium counter-anions confer ion-pairing and lipophilicity properties that modulate membrane diffusion of the salt. Extracellular recordings in different cortical areas demonstrated the presence of epileptiform activities that strongly relate to anion identity, following the qualitative order of the Hofmeister series. Indeed, highly lipophilic salts that easily cross the BBB enhanced extracellular potassium concentration measured by ion-selective electrodes and were the most effective pro-epileptic species. This study constitutes a novel contribution for the understanding of the potential epileptogenicity of potassium salts and, more generally, of the role of counter-anions in the passive passage of salts through biological membranes.
authors.affiliation: Unit of Epileptology and Experimental Neurophysiology, Fondazione Istituto Neurologico Carlo Besta, Milano, Italy ; Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Breschi
authors.forename: Massimo
authors.initials: M
authors.lastname: Cametti
authors.forename: Alfonso
authors.initials: A
authors.lastname: Mastropietro
authors.forename: Laura
authors.initials: L
authors.lastname: Librizzi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Baselli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Resnati
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Metrangolo
authors.forename: Marco
authors.initials: M
authors.lastname: de Curtis
mesh_terms: D000818:Animals; D001692:Biological Transport; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D005071:Evoked Potentials / Q000187:drug effects; D006168:Guinea Pigs; D057927:Hydrophobic and Hydrophilic Interactions; D010539:Permeability; D011188:Potassium / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D012492:Salts / Q000378:metabolism*; D012640:Seizures / Q000139:chemically induced
chemical_list: D012492:Salts; D011188:Potassium