Kelley D S, Campbell H A, Potter V R
J Cell Physiol. 1982 Jul;112(1):67-75. doi: 10.1002/jcp.1041120111.
Uptake of 2-aminoisobutyric acid (AIB) at concentrations of 0.1 mM to 30 mM was examined in sodium-containing and sodium-free media in hepatocytes pretreated without hormones (control), with hormones, or with amino acid depletion. Results show that 1-minute but not 4-minute rates can be taken as initial rates for the total or sodium-dependent transport of AIB. The data for the 1-minute sodium-dependent transport of AIB were analyzed by a computer program and also by Eadie-Hofstee and Lineweaver-Burk plots, and a single saturable system was found. In the control cultures, the saturable system had a Km of 1-2 mM AIB and a Vmax of 1.2 nmoles AIB/mg protein/minute. There was an increase in the Vmax of two to three-fold after pretreating the cultures with insulin or amino acid depletion, three to four-fold with glucagon, and six to seven fold with glucagon + dexamethasone.
在含有钠和不含钠的培养基中，对未经激素预处理（对照）、经激素预处理或氨基酸耗竭预处理的肝细胞，检测了浓度为0.1 mM至30 mM的2-氨基异丁酸（AIB）摄取情况。结果表明，1分钟而非4分钟的摄取速率可作为AIB总转运或钠依赖性转运的初始速率。用计算机程序以及伊迪-霍夫斯泰（Eadie-Hofstee）和林韦弗-伯克（Lineweaver-Burk）作图法分析了AIB 1分钟钠依赖性转运的数据，发现存在一个单一的可饱和系统。在对照培养物中，该可饱和系统的米氏常数（Km）为1 - 2 mM AIB，最大反应速率（Vmax）为1.2纳摩尔AIB/毫克蛋白质/分钟。在用胰岛素预处理培养物或进行氨基酸耗竭后，Vmax增加了两到三倍；用胰高血糖素预处理后，增加了三到四倍；用胰高血糖素 + 地塞米松预处理后，增加了六到七倍。
