Koizumi T, Bamba T, Hosoda S
Second Department of Internal Medicine, Shiga University of Medical Science, Japan.
Gastroenterol Jpn. 1993 Jun;28(3):385-92. doi: 10.1007/BF02776983.
The effects of cholecystokinin octapeptide (CCK8) on amino acid transport and protein synthesis in the pancreatic acini were determined. The question of whether those effects differed between amino acid transport systems A and L was also investigated. The influx of alpha-[3H]aminoisobutyric acid (AIB, system A) and [14C]cycloleucine (system L) into isolated rat pancreatic acini and the incorporation of [14C]alanine (system A) and [3H]leucine (system L) into trichloroacetic acid (TCA)-precipitable protein in pancreatic acini were studied in the presence of various concentrations of CCK8. CCK inhibited the amino acid transport across the basolateral membrane of pancreatic acini. This effect was mediated by Ca2+, and was more responsive to amino acid transport system L than to A. CCK also inhibited protein synthesis in pancreatic acini in a dose-dependent manner. The inhibition of protein synthesis by CCK was thought to be mainly due to the inhibition of amino acid transport by CCK. Therefore, the predominant utilization of extracellular amino acids in protein synthesis was suggested.
测定了八肽胆囊收缩素（CCK8）对胰腺腺泡中氨基酸转运和蛋白质合成的影响。还研究了这些影响在氨基酸转运系统A和L之间是否存在差异的问题。在存在不同浓度CCK8的情况下，研究了α-[³H]氨基异丁酸（AIB，系统A）和[¹⁴C]环亮氨酸（系统L）流入分离的大鼠胰腺腺泡以及[¹⁴C]丙氨酸（系统A）和[³H]亮氨酸（系统L）掺入胰腺腺泡中三氯乙酸（TCA）沉淀蛋白的情况。CCK抑制氨基酸跨胰腺腺泡基底外侧膜的转运。这种作用由Ca²⁺介导，并且对氨基酸转运系统L的反应比对系统A更敏感。CCK还以剂量依赖性方式抑制胰腺腺泡中的蛋白质合成。CCK对蛋白质合成的抑制作用被认为主要是由于CCK对氨基酸转运的抑制。因此，提示在蛋白质合成中细胞外氨基酸的主要利用情况。
