Chow S Y, Yen-Chow Y C, White H S, Hertz L, Woodbury D M
Department of Physiology, University of Utah, Salt Lake City 84108.
Neurochem Res. 1991 Dec;16(12):1275-83. doi: 10.1007/BF00966658.
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)
在星形胶质细胞中，随着细胞外钾离子浓度（[K⁺]o）从1.2 mM增加到10 mM，细胞内钾离子浓度（[K⁺]i）和氯离子浓度（[Cl⁻]i）升高，而细胞内钠离子浓度（[Na⁺]i）降低。当[K⁺]o从10 mM增加到60 mM时，这三种离子的细胞内浓度无显著变化。当[K⁺]o从60 mM增加到122 mM时，观察到[K⁺]i和[Cl⁻]i增加，[Na⁺]i降低。在神经元中，随着[K⁺]o从1.2 mM增加到2.8 mM，[Na⁺]i和[Cl⁻]i降低，而[K⁺]i升高。当[K⁺]o从2.8 mM增加到30 mM时，[K⁺]i、[Na⁺]i和[Cl⁻]i无显著变化。当[K⁺]o从30 mM增加到122 mM时，[K⁺]i和[Cl⁻]i升高，而[Na⁺]i降低。在星形胶质细胞中，当[K⁺]o升高时细胞内pH值（pHi）增加。在神经元中，pHi有双相变化。在较低的[K⁺]o（1.2 - 2.8 mM）时，pHi随着[K⁺]o升高而降低，而在较高的[K⁺]o（2.8 - 122 mM）时，pHi与[K⁺]o直接相关。在星形胶质细胞和神经元中，[K⁺]o的变化均不影响细胞外水含量，而细胞内水含量随着[K⁺]o升高而增加。用铊 - 204测量的跨膜电位（Em）在1.2 mM至90 mM的[K⁺]o范围内与[K⁺]o呈负相关，[K⁺]o增加10倍使星形胶质细胞去极化约56 mV，使神经元去极化约52 mV。除了在较低[K⁺]o时的神经元外，用铊 - 204测量的Em值接近钾离子平衡电位（Ek）。然而，在[K⁺]o低于30 mM时，星形胶质细胞和神经元的Em值均不等于氯离子平衡电位（ECl）。（摘要截选至250字）
