Membrane Ion Transport in Bartter’s Syndrome

Abstract

Abstract Fifteen patients with Bartter’s syndrome (hyponatremic hypochloremic hypokalemic metabolic alkalosis) were compared with 15 healthy volunteers. Red blood cell Na + /H + and Cl − /HCO 3 − exchanges were enhanced in all patients with Bartter’s syndrome. In calciuric normomagnesemic patients, sensitive to nonsteroidal anti-inflammatory drugs (classic Bartter’s syndrome), red blood cell Na + ,K + ,2Cl − cotransport was markedly reduced, calcium-dependent K + permeability was moderately increased, and up to 60% of sodium permeability was represented by cAMP-activated fraction (presumably human analog of β-isoform of Na + /H + exchange). In noncalciuric hypomagnesemic patients insensitive to indomethacin (Gitelman’s syndrome), Na + ,K + ,2Cl − cotransport was enhanced, Na + permeability was increased due to calmodulin-dependent fraction, and calcium-dependent K + permeability was markedly enhanced. A new subtype of Bartter-like syndrome (“variant Bartter’s syndrome”) has been described in which calciuria, hypomagnesemia, and insensitivity to nonsteroidal anti-inflammatory drugs were associated with decreased Na + ,K + ,2Cl − cotransport, enhanced calmodulin-activated fraction of Na + influx, and reduced calcium-dependent K + permeability.