title: Preferential expression of plasmalemmal K-dependent Na+/Ca2+ exchangers in neurons versus astrocytes.
abstract: Numerous isoforms of plasmalemmal K-dependent (NCKX) and K-independent (NCX) Na+/Ca2+ exchangers are expressed in the brain. The physiological functions of each isoform are presently unknown. Therefore, in this study, we compared expression of NCKX and NCX transcripts between primary cultures of cerebellar granule cells, and astrocytes. Northern blot analysis showed that granule cells expressed NCKX2, NCKX3, NCKX4 and NCX3, whereas astrocytes expressed primarily NCX1. Consistent with this molecular characterization, a significant fraction of 45Ca2+ accumulation in Na-loaded granule cells, but not in astrocytes, depended on external K+. This is the first demonstration of native NCKX activity in neurons derived from the central nervous system. Our data suggest that NCKX isoform expression may correspond to the unique Ca2+ homeostasis requirements of neurons.
authors.affiliation: The Psychiatric Institute, Department of Psychiatry, The University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60612, USA.
authors.forename: Lech
authors.initials: L
authors.lastname: Kiedrowski
authors.forename: Aneta
authors.initials: A
authors.lastname: Czyz
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Li
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lytton
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002132:Calcium Radioisotopes / Q000493:pharmacokinetics; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D015870:Gene Expression / Q000502:physiology; D007150:Immunohistochemistry; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000032:analysis / Q000235:genetics* / Q000378:metabolism
chemical_list: D002132:Calcium Radioisotopes; D012333:RNA, Messenger; C511590:Slc24a3 protein, rat; D019831:Sodium-Calcium Exchanger; C074530:potassium-dependent sodium-calcium exchanger; D012964:Sodium; D011188:Potassium; D002118:Calcium