Torlińska T, Maćkowiak P, Nogowski L, Nowak K W, Madry E, Perz M
Department of Physiology, University of Medical Sciences, Poznań, Poland.
J Physiol Pharmacol. 1998 Jun;49(2):261-70.
The first step in insulin action is its specific binding to alpha-subunits of the receptor in the plasma membrane. Rats of Wistar strain are commonly used as laboratory animals but there are no data comparing insulin binding by various rat tissues. We studied the insulin binding kinetics in plasma membranes isolated from hearts, livers, brains, skeletal muscles, adipose tissue, thymus and testes in order to compare their ability to bind 125I-insulin and to test which membrane preparation is most useful and convenient for such a study. The dissociation constant (Kd) and the quantity of receptors measured as a binding capacity were determined by the Scatchard method using the LIGAND computer program whereas the binding potency of insulin was calculated as IC50 using the ALLFIT computer program. We also introduced the product of Ka x R50 (affinity constant multiplied by binding capacity) as an index which describes the functional features of insulin receptors taking into account both number of insulin receptors and their affinity. Taking all the parameters of insulin binding tested together we can conclude that the liver and, to some extent, adipose tissue may provide a useful model for studying hormone-receptor interaction. By contrast, to the group of rat tissues responding rather poorly to insulin belong thymus and testis.
胰岛素作用的第一步是其与质膜中受体的α亚基特异性结合。Wistar品系的大鼠通常用作实验动物，但尚无关于比较不同大鼠组织胰岛素结合情况的数据。我们研究了从心脏、肝脏、大脑、骨骼肌、脂肪组织、胸腺和睾丸分离的质膜中的胰岛素结合动力学，以比较它们结合125I标记胰岛素的能力，并测试哪种膜制剂对于此类研究最有用且方便。解离常数（Kd）和作为结合能力测定的受体数量通过使用LIGAND计算机程序的Scatchard方法确定，而胰岛素的结合效力使用ALLFIT计算机程序计算为IC50。我们还引入了Ka×R50（亲和常数乘以结合能力）的乘积作为一个指标，该指标在考虑胰岛素受体数量及其亲和力的同时描述胰岛素受体的功能特征。综合考虑所测试的胰岛素结合的所有参数，我们可以得出结论，肝脏以及在一定程度上脂肪组织可能为研究激素 - 受体相互作用提供有用的模型。相比之下，对胰岛素反应相当差的大鼠组织包括胸腺和睾丸。
