Matsumoto P S, Ohara A, Duchatelle P, Eaton D C
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322.
Am J Physiol. 1993 Jan;264(1 Pt 1):C246-50. doi: 10.1152/ajpcell.1993.264.1.C246.
Insulin increases epithelial Na+ reabsorption, and many of its actions involve tyrosine kinase. We used tyrosine kinase inhibitors to examine the role of tyrosine kinase in the action of insulin. Pretreatment of Na+ transporting cells with tyrosine kinase inhibitors attenuates the subsequent action of insulin, suggesting that the action of insulin on epithelial Na+ transport involves tyrosine kinase activity. In addition to their effect on insulin-induced Na+ transport, the tyrosine kinase inhibitors also significantly reduce Na+ transport in Na(+)-transporting epithelial cells, suggesting that there is a significant tonic tyrosine kinase activity that modulates epithelial Na+ transport. Using patch-clamp methods, we found that one inhibitor, genistein, reduces the number of active Na+ channels in cell-attached patches without significantly affecting the open probability of any remaining channels. The effects of the tyrosine kinase inhibitors are not due to inhibition of protein kinase A (PKA), since H89, a PKA inhibitor, does not affect Na+ transport of control cells (as the tyrosine kinase inhibitors do), and the tyrosine kinase inhibitor, genistein or tyrphostin 23, does not alter the stimulation of ion transport by 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate, a membrane-permeable adenosine 3',5'-cyclic monophosphate analogue (as H89 does).
胰岛素可增加上皮细胞对钠离子的重吸收，其许多作用都涉及酪氨酸激酶。我们使用酪氨酸激酶抑制剂来研究酪氨酸激酶在胰岛素作用中的角色。用酪氨酸激酶抑制剂对钠离子转运细胞进行预处理会减弱胰岛素随后的作用，这表明胰岛素对上皮细胞钠离子转运的作用涉及酪氨酸激酶活性。除了对胰岛素诱导的钠离子转运有影响外，酪氨酸激酶抑制剂还显著降低了钠离子转运上皮细胞中的钠离子转运，这表明存在显著的持续性酪氨酸激酶活性来调节上皮细胞的钠离子转运。使用膜片钳方法，我们发现一种抑制剂染料木黄酮可减少细胞贴附膜片中活性钠离子通道的数量，而不会显著影响任何剩余通道的开放概率。酪氨酸激酶抑制剂的作用并非由于对蛋白激酶A（PKA）的抑制，因为PKA抑制剂H89不会影响对照细胞的钠离子转运（与酪氨酸激酶抑制剂的作用不同），并且酪氨酸激酶抑制剂染料木黄酮或 tyrphostin 23不会改变8 -（4 - 氯苯硫基）腺苷3',5'-环磷酸酯（一种膜通透性腺苷3',5'-环磷酸酯类似物）对离子转运的刺激作用（与H89的作用不同）。
