Casavola V, Helmle-Kolb C, Murer H
Department of Physiology, University of Zurich, Switzerland.
Biochem Biophys Res Commun. 1989 Dec 15;165(2):833-7. doi: 10.1016/s0006-291x(89)80041-5.
Epithelial layers of LLC-PK1/PKE20 cells, a renal epithelial cell line which expresses Na+/H+ exchange activities in the apical as well as basolateral membrane domains, are examined in the single cell mode by microspectrofluorometry. We provide evidence that basolateral Na+/H+ exchange is more sensitive to amiloride inhibition than is apical Na+/H+ exchange. Furthermore, we demonstrate that the two exchange activities differ in their regulatory control: kinase A activation (forskolin, 8-Br-cAMP) leads to inhibition of both exchange activities, whereas kinase C activation (phorbol ester) stimulates basolateral and inhibits apical Na+/H+ exchange. Thus, renal epithelial cells may contain two Na+/H+ exchange activities: an apical ("epithelial") and basolateral ("housekeeping") which may serve different cellular functions and are under separate regulatory controls.
LLC-PK1/PKE20细胞系是一种肾上皮细胞系，其顶端和基底外侧膜结构域均表达Na⁺/H⁺交换活性，采用显微分光荧光测定法以单细胞模式对其上皮层进行了检测。我们提供的证据表明，基底外侧Na⁺/H⁺交换比顶端Na⁺/H⁺交换对氨氯吡咪抑制更敏感。此外，我们证明这两种交换活性在调节控制方面存在差异：蛋白激酶A激活（福斯可林、8-溴-cAMP）导致两种交换活性均受到抑制，而蛋白激酶C激活（佛波酯）则刺激基底外侧Na⁺/H⁺交换并抑制顶端Na⁺/H⁺交换。因此，肾上皮细胞可能含有两种Na⁺/H⁺交换活性：一种顶端（“上皮性”）和基底外侧（“管家型”）活性，它们可能发挥不同的细胞功能并受不同的调节控制。
