Stimulation of Na+-K+-2Cl- cotransporter in neuronal cells by excitatory neurotransmitter glutamate.
Na+-K+-2Cl- cotransporters are important in renal salt reabsorption and in salt secretion by epithelia. They are also essential in maintenance and regulation of ion gradients and cell volume in both epithelial and nonepithelial cells. Expression of Na+-K+-2Cl- cotransporters in brain tissues is high; however, little is known about their function and regulation in neurons. In this study, we examined regulation of the Na+-K+-2Cl- cotransporter by the excitatory neurotransmitter glutamate. The cotransporter activity in human neuroblastoma SH-SY5Y cells was assessed by bumetanide-sensitive K+ influx, and protein expression was evaluated by Western blot analysis. Glutamate was found to induce a dose- and time-dependent stimulation of Na+-K+-2Cl- cotransporter activity in SH-SY5Y cells. Moreover, both the glutamate ionotropic receptor agonist N-methyl-D-aspartic acid (NMDA) and the metabotropic receptor agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) significantly stimulated the cotransport activity in these cells. NMDA-mediated stimulation of the Na+-K+-2Cl- cotransporter was abolished by the selective NMDA-receptor antagonist (+)-MK-801 hydrogen maleate. trans-ACPD-mediated effect on the cotransporter was blocked by the metabotropic receptor antagonist (+)-alpha-methyl-(4-carboxyphenyl)glycine. The results demonstrate that Na+-K+-2Cl- cotransporters in neurons are regulated by activation of both ionotropic and metabotropic glutamate receptors.
Sun
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Department of Neurological Surgery, School of Medicine, University of Wisconsin, Madison, Wisconsin 53792, USA.
Murali
S G
SG
D002034:Bumetanide / Q000494:pharmacology; D002352:Carrier Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D018698:Glutamic Acid / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D016202:N-Methylaspartate / Q000494:pharmacology; D009447:Neuroblastoma; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000096:biosynthesis / Q000235:genetics; D028021:Sodium-Potassium-Chloride Symporters; D014407:Tumor Cells, Cultured; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D002352:Carrier Proteins; D018683:Excitatory Amino Acid Agents; D017470:Receptors, Glutamate; D028021:Sodium-Potassium-Chloride Symporters; D003515:Cycloleucine; D002034:Bumetanide; C036361:1-amino-1,3-dicarboxycyclopentane; D018698:Glutamic Acid; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D011188:Potassium