Botchkin L M, Matthews G
Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794-5230.
Proc Natl Acad Sci U S A. 1994 May 10;91(10):4564-8. doi: 10.1073/pnas.91.10.4564.
Whole-cell patch-clamp recordings were made from isolated cells of the retinal pigment epithelium (RPE) of neonatal rats. After 24 hr in cell culture, RPE cells developed a transient, voltage-activated inward current that was never observed in acutely isolated cells. The kinetics, voltage-dependence, and reversal potential of the current and its dependence on external sodium demonstrated that the current was due to the expression of voltage-activated Na+ channels in cultured RPE cells. The current was partly blocked by tetrodotoxin at low concentrations (< 100 nM), but a second component of Na+ current was unblocked by tetrodotoxin at concentrations up to 10 microM. Na+ channels were present in cultured RPE cells at sufficient density to support regenerative action potentials in voltage recordings. Both the epithelial cells of the RPE and the neurons of the retina derive embryonically from neural origin, and it is known that under certain circumstances, nonmammalian RPE cells retain the ability to take on neuronal characteristics. The development of voltage-activated Na+ channels and the presence of action potentials demonstrate that neonatal mammalian RPE cells are also capable of expressing neuronal characteristics in cell culture.
采用全细胞膜片钳记录技术，从新生大鼠视网膜色素上皮（RPE）的分离细胞进行记录。在细胞培养24小时后，RPE细胞产生了一种短暂的、电压激活的内向电流，而在急性分离的细胞中从未观察到这种电流。该电流的动力学、电压依赖性、反转电位及其对细胞外钠离子的依赖性表明，该电流是由于培养的RPE细胞中电压激活的Na⁺通道的表达所致。该电流在低浓度（<100 nM）时部分被河豚毒素阻断，但在浓度高达10 μM时，Na⁺电流的第二个成分不受河豚毒素阻断。培养的RPE细胞中存在足够密度的Na⁺通道，以支持电压记录中的再生动作电位。RPE的上皮细胞和视网膜神经元在胚胎发育上均起源于神经，并且已知在某些情况下，非哺乳动物的RPE细胞保留了获得神经元特征的能力。电压激活的Na⁺通道的发育和动作电位的存在表明，新生哺乳动物RPE细胞在细胞培养中也能够表达神经元特征。
