Effects of potassium on the anion and cation contents of primary cultures of mouse astrocytes and neurons.
In astrocytes, as [K+]o was increased from 1.2 to 10 mM, [K+]i and [Cl-]i were increased, whereas [Na+]i was decreased. As [K+]o was increased from 10 to 60 mM, intracellular concentration of these three ions showed no significant change. When [K+]o was increased from 60 to 122 mM, an increase in [K+]i and [Cl-]i and a decrease in [Na+]i were observed. In neurons, as [K+]o was increased from 1.2 to 2.8 mM, [Na+]i and [Cl-]i were decreased, whereas [K+]i was increased. As [K+]o was increased from 2.8 to 30 mM, [K+]i, [Na+]i and [Cl-]i showed no significant change. When [K+]o was increased from 30 to 122 mM, [K+]i and [Cl-]i were increased, whereas [Na+]i was decreased. In astrocytes, pHi increased when [K+]o was increased. In neurons, there was a biphasic change in pHi. In lower [K+]o (1.2-2.8 mM) pHi decreased as [K+]o increased, whereas in higher [K+]o (2.8-122 mM) pHi was directly related to [K+]o. In both astrocytes and neurons, changes in [K+]o did not affect the extracellular water content, whereas the intracellular water content increased as the [K+]o increased. Transmembrane potential (Em) as measured with Tl-204 was inversely related to [K+]o between 1.2 and 90 mM, a ten-fold increase in [K+]o depolarized the astrocytes by about 56 mV and the neurons about 52 mV. The Em values measured with Tl-204 were close to the potassium equilibrium potential (Ek) except those in neurons at lower [K+]o. However, they were not equal to the chloride equilibrium potential (ECl) at [K+]o lower than 30 mM in both astrocytes and neurons.(ABSTRACT TRUNCATED AT 250 WORDS)
Chow
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SY
Department of Physiology, University of Utah, Salt Lake City 84108.
Yen-Chow
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YC
White
H S
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Hertz
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L
Woodbury
D M
DM
D000818:Animals; D000838:Anions; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002412:Cations; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D014867:Water / Q000378:metabolism
D000838:Anions; D002412:Cations; D002712:Chlorides; D009419:Nerve Tissue Proteins; D014867:Water; D012964:Sodium; D011188:Potassium