Activity-dependent regulation of Na+, K(+)-ATPase alpha isoform mRNA expression in vivo.
To investigate the functional role of the different Na+, K(+)-ATPase alpha (catalytic) subunit isoforms in neuronal cells, we used quantitative in situ hybridization with riboprobes specific for alpha 1, alpha 2, and alpha 3 isoforms to measure the level of alpha isoform-specific expression in the neuroendocrine cells of the supraoptic (SON) and paraventricular (PVN) nuclei of rat hypothalamus. A prolonged increase in electrical activity of these cells, achieved by 5 days of salt treatment, increased the amount of alpha 1 isoform mRNA in the SON and PVN by 50%. Levels of alpha 1 mRNA in other brain regions and levels of alpha 2 and alpha 3 mRNAs were not affected by salt treatment. We conclude that the alpha 1 isoform Na+, K(+)-ATPase may be specifically adapted to pump out Na+, which enters the cells through voltage-gated channels during neuronal depolarization.
Mata
M
M
Department of Neurology, University of Michigan, Ann Arbor.
Hieber
V
V
Beaty
M
M
Clevenger
M
M
Fink
D J
DJ
D000818:Animals; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D007527:Isoenzymes / Q000235:genetics* / Q000502:physiology; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry / Q000201:enzymology; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000502:physiology; D013495:Supraoptic Nucleus / Q000737:chemistry / Q000201:enzymology; D009435:Synaptic Transmission / Q000502:physiology
D007527:Isoenzymes; D012333:RNA, Messenger; D015222:Sodium Channels; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase