Cobb M H, Skipski I A, Scott W N
Ann N Y Acad Sci. 1981;372:247-71. doi: 10.1111/j.1749-6632.1981.tb15480.x.
Insulin increases active sodium transport by the toad urinary bladder, an effect that begins with 15 minutes and persists for at least 20 hours. Although pretreatment of bladders with inhibitors of RNA or protein synthesis has no effect on the response to insulin within the first hour, these agents block the long-term component of insulin-stimulated sodium transport. To examine the relationship of protein synthesis to the sustained increase in sodium transport elicited by insulin, we have studied the effects of the hormone upon the incorporation of radioactive amino acids into mucosal cell proteins. There is no detectable effect of insulin on the uptake of aminoisobutyric acid into mucosal cells or on the incorporation of labeled precursors into total protein; however, using a dual-label technique, we find that insulin increases the incorporation of amino acids into specific soluble and plasma-membrane proteins of granular mucosal cells. Insulin has no discernible effect upon the incorporation of amino acids into proteins of mitochondria-rich mucosal cells. Thus the effects of insulin upon sodium transport appear to be the result of two separate mechanisms, (1) a short-term response that is independent of protein synthesis and (2) a long-term response that is expressed after the first hour of hormone treatment and that requires the synthesis of one or more specific proteins in the granular cell.
胰岛素可增加蟾蜍膀胱的活性钠转运，这种作用在15分钟时开始，并持续至少20小时。虽然用RNA或蛋白质合成抑制剂对膀胱进行预处理在最初1小时内对胰岛素反应没有影响，但这些试剂会阻断胰岛素刺激的钠转运的长期成分。为了研究蛋白质合成与胰岛素引起的钠转运持续增加之间的关系，我们研究了该激素对放射性氨基酸掺入黏膜细胞蛋白质的影响。胰岛素对氨基异丁酸进入黏膜细胞或标记前体掺入总蛋白质没有可检测到的影响；然而，使用双标记技术，我们发现胰岛素增加了氨基酸掺入颗粒状黏膜细胞的特定可溶性和血浆膜蛋白中。胰岛素对富含线粒体的黏膜细胞蛋白质中氨基酸的掺入没有明显影响。因此，胰岛素对钠转运的作用似乎是两种独立机制的结果，（1）一种独立于蛋白质合成的短期反应，（2）一种在激素处理第一小时后出现的长期反应，并且需要在颗粒细胞中合成一种或多种特定蛋白质。
