Expression and regulation of Na pump isoforms in cultured cerebellar granule cells.
We investigated expression of Na pump isoforms in cultured cerebellar granule cells and measured in situ ion pump activities of the isoforms, to elucidate functions of Na pump isoforms in neurons. The cells expressed three Na pump isoforms (alpha1, alpha2 and alpha3 isoforms), however the alpha1 isoform acted as a main ion pump under basal conditions. The ion pump activity of the alpha3/ alpha2 isoforms increased remarkably after stimulation of the neurons with glutamate, therefore the alpha3/alpha2 isoforms as well as the alpha1 isoform acted as ion pumps after the stimulation. The glutamate effects were mainly mediated by non-NMDA receptors. These results suggest that alpha1 isoform and alpha3/alpha2 isoforms are functionally important under basal conditions and after neuronal excitation, respectively.
Department of Biochemistry I, Yokohama City University School of Medicine, Yokohama, Japan.
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Soga
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Nakayama
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Inoue
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002531:Cerebellum / Q000166:cytology; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000201:enzymology*; D018696:Neuroprotective Agents / Q000494:pharmacology; D011197:Potassium Radioisotopes / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D007527:Isoenzymes; D018696:Neuroprotective Agents; D011197:Potassium Radioisotopes; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D018698:Glutamic Acid; D016202:N-Methylaspartate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D000254:Sodium-Potassium-Exchanging ATPase; D007608:Kainic Acid