Membrane Ion Transport in Bartter's Syndrome: Evidence for a New Syndrome Subtype

Fifteen patients with Bartter's syndrome (hyponatremic hypochloremic hypokalemic metabolic alkalosis) were compared with 15 healthy volunteers. Red blood cell Na and Cl3 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 beta-isoform of Na 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. (Hypertension. 1997;30:1338-1341.)