title: Intracellular calcium and sodium-lithium countertransport in type 2 diabetic patients with and without albuminuria.
abstract: Increased intracellular calcium concentrations ([Ca(2+)](i)) and enhanced sodium-lithium countertransport (Na/Li CT) activities may play a role in the development of diabetic complications such as diabetic nephropathy. The present study was designed to test the hypothesis that albuminuria in patients with type 2 diabetes is associated with increased [Ca(2+)](i) in response to stimulation with platelet-activating factor (PAF) or with enhanced Na/Li CT activities. The study population comprised 203 type 2 diabetic patients. Albuminuria was defined as an albumin excretion rate exceeding 30 mg/d (117 cases). PAF-evoked rises in [Ca(2+)](i) and Na/Li CT activities were determined in Epstein-Barr-virus-immortalized lymphoblasts. Albuminuria was related to high stimulated [Ca(2+)](i) but not to high basal [Ca(2+)](i). The association was independent of age, sex and several non-diabetes related confounders, but depended on diabetes-related factors, such as the duration of diabetes. The risk of albuminuria was highest in subjects with high [Ca(2+)](i) who reported a diabetes duration of < or =10 years. There was no association between Na/Li CT activities and albuminuria. The present results support the hypothesis that albuminuria in type 2 diabetic patients is associated with a primary defect in intracellular calcium homeostasis. The association between stimulated [Ca(2+)](i) and albuminuria is most prominent in early diabetes.
authors.affiliation: Institute of Epidemiology and Social Medicine, Ernst Moritz Arndt University Greifswald, Germany.
authors.forename: Henry
authors.initials: H
authors.lastname: Völzke
authors.forename: Sybille
authors.initials: S
authors.lastname: Gruska
authors.forename: Dirk
authors.initials: D
authors.lastname: Vogelgesang
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kerner
authors.forename: Günter
authors.initials: G
authors.lastname: Kraatz
authors.forename: Rainer
authors.initials: R
authors.lastname: Rettig
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000419:Albuminuria / Q000209:etiology / Q000378:metabolism*; D002118:Calcium / Q000032:analysis*; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000378:metabolism*; D005260:Female; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry; D017136:Ion Transport; D008094:Lithium / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012964:Sodium / Q000378:metabolism*
chemical_list: D008094:Lithium; D012964:Sodium; D002118:Calcium