青蛙视网膜色素上皮的钾离子转运：视网膜下间隙中钾离子活性的自动调节。
Potassium transport of the frog retinal pigment epithelium: autoregulation of potassium activity in the subretinal space.
作者信息
la Cour M, Lund-Andersen H, Zeuthen T
出版信息
J Physiol. 1986 Jun;375:461-79. doi: 10.1113/jphysiol.1986.sp016128.
The K+ transport of the isolated retinal pigment epithelium from the bull-frog was studied using micropuncture with double-barrelled ion-selective micro-electrodes. Transient changes of intracellular values of electrical potential and K+ activity were monitored in response to abrupt changes in the K+ concentration on the retinal side of the tissue. The data were interpreted in terms of a simple three-compartment model of the epithelium in which the retinal (or apical) and choroidal (or basal) membranes separate the cellular compartment from the retinal and choroidal compartments. K+ transport across the retinal membrane was described by an active ouabain-sensitive K+ influx in parallel with a passive electrodiffusive K+ efflux. In steady state under control conditions, the active K+ influx (pump rate) averaged 0.18 X 10(-9) mol cm-2 s-1. The electrodiffusive K+ efflux was described by a K+ permeability, which in steady state under control conditions averaged 1.7 X 10(-5) cm s-1. K+ transport across the choroidal membrane was described as purely electrodiffusive. In steady state under control conditions, the K+ permeability of the choroidal membrane averaged 0.6 X 10(-5) cm s-1. When the K+ concentration on the retinal side of the tissue was increased from its control value, the K+ permeability of the retinal membrane decreased and the K+ permeability of the choroidal membrane increased. This caused the epithelium to attain a new steady state in which the cells transported K+ away from the retinal compartment at a high rate. When the K+ concentration on the retinal side of the tissue was decreased from its control value, the K+ permeability of the retinal membrane increased and the pump rate decreased. This caused the epithelial cells to transport K+ from the cellular compartment into the retinal compartment. In effect, the K+ transport of the retinal pigment epithelium depends on the K+ concentration in the retinal compartment in such a way as to keep variations in this concentration at a minimum.
采用双管离子选择性微电极微穿刺技术，对牛蛙分离的视网膜色素上皮细胞的钾离子转运进行了研究。针对组织视网膜侧钾离子浓度的突然变化，监测了细胞内电位和钾离子活性的瞬时变化。数据依据上皮细胞的简单三室模型进行解释，其中视网膜（或顶端）膜和脉络膜（或基底）膜将细胞室与视网膜室和脉络膜室分隔开来。视网膜膜上的钾离子转运表现为哇巴因敏感的主动钾离子内流与被动电扩散钾离子外流并存。在对照条件下的稳态中，主动钾离子内流（泵浦速率）平均为0.18×10⁻⁹ mol·cm⁻²·s⁻¹。电扩散钾离子外流由钾离子通透性描述，在对照条件下的稳态中，其平均值为1.7×10⁻⁵ cm·s⁻¹。脉络膜膜上的钾离子转运被描述为纯粹的电扩散。在对照条件下的稳态中，脉络膜膜的钾离子通透性平均为0.6×10⁻⁵ cm·s⁻¹。当组织视网膜侧的钾离子浓度从对照值升高时，视网膜膜的钾离子通透性降低，而脉络膜膜的钾离子通透性增加。这使得上皮细胞达到一个新的稳态，在此稳态下细胞以高速率将钾离子从视网膜室转运出去。当组织视网膜侧的钾离子浓度从对照值降低时，视网膜膜的钾离子通透性增加，泵浦速率降低。这导致上皮细胞将钾离子从细胞室转运到视网膜室。实际上，视网膜色素上皮细胞的钾离子转运依赖于视网膜室中的钾离子浓度，从而使该浓度的变化保持在最小值。
Zotero 插件