Higgins L S, Berg D K
Department of Biology, University of California, San Diego, La Jolla 92093.
J Cell Biol. 1988 Sep;107(3):1157-65. doi: 10.1083/jcb.107.3.1157.
Bovine adrenal chromaffin cells have nicotinic acetylcholine receptors (AChRs) that mediate release of catecholamines from the cells in response to synaptic input, and resemble neuronal AChRs in pharmacology and antigenic profile. Results presented here show that a cAMP-dependent process enhances the function of adrenal chromaffin AChRs as a population in the plasma membrane. This was demonstrated by showing that cAMP analogues cause specific increases both in the level of nicotine-induced catecholamine release from the cells and in the level of the nicotine-induced conductance change occurring in the cells. Neither de novo synthesis of receptors nor transport of preexisting intracellular receptors to the plasma membrane is necessary for the enhancement. The responsiveness of AChRs to regulation by the cAMP-dependent process appears to depend on the length of time the receptors have been on the cell surface. AChRs newly inserted into the plasma membrane generate a greater nicotinic response than do older AChRs and, unlike older AChRs, their response to agonist is not enhanced after treatment of the cells with cAMP analogues. The findings indicate that the AChRs and/or associated components undergo a maturation in the plasma membrane that alters their function and their regulation by secondary messenger systems.
牛肾上腺嗜铬细胞具有烟碱型乙酰胆碱受体（AChRs），该受体可介导细胞响应突触输入释放儿茶酚胺，并且在药理学和抗原特性方面类似于神经元AChRs。本文给出的结果表明，一种cAMP依赖性过程可增强肾上腺嗜铬细胞AChRs作为质膜上群体的功能。这通过以下方面得以证明：cAMP类似物可使细胞中尼古丁诱导的儿茶酚胺释放水平以及细胞中尼古丁诱导的电导变化水平特异性增加。增强过程既不需要受体的从头合成，也不需要将预先存在的细胞内受体转运至质膜。AChRs对cAMP依赖性过程调节的反应性似乎取决于受体在细胞表面存在的时间长度。新插入质膜的AChRs比旧的AChRs产生更大的烟碱反应，并且与旧的AChRs不同，在用cAMP类似物处理细胞后，它们对激动剂的反应不会增强。这些发现表明，AChRs和/或相关成分在质膜中经历成熟过程，这会改变它们的功能以及它们受第二信使系统调节的方式。
