Rehfeld J F, Holst J J, Jensen S L
Regul Pept. 1982 Jan;3(1):15-28. doi: 10.1016/0167-0115(82)90003-9.
Using sequence-specific radioimmunoassays, the quantities and molecular nature of cholecystokinin (CCK) have been determined in extracts of porcine duodenal mucosa and in the vascular perfusate from the isolated porcine duodenum. The basal concentration of CCK in the perfusate was 84 pM equiv. CCK-8 (mean; range: 32-173 pM, n = 5). After intraluminal stimulation with amino acids, acidified fat emulsions and hydrochloric acid, the concentrations increased 2--5-fold. Both in the basal and stimulated state the concentrations of the related hormone, gastrin, were below 5 pM equiv. gastrin-17. CCK in the perfusate was concentrated by affinity-chromatography using antibodies directed against the bioactive C-terminus. Subsequent gel chromatography revealed a form with a size like or slightly larger than the C-terminal dodecapeptide (CCK-12), a predominant form resembling the C-terminal octapeptide (CCK-8), and a form resembling the C terminal tetrapeptide (CCK-4). The duodenal mucosa contained in addition CCK-33, -39 and CCK-peptides with further N-terminal extensions. The results suggest that small CCK peptides are the principal circulating forms, while CCK-33 and larger forms are biosynthetic precursors.
利用序列特异性放射免疫测定法，已测定了猪十二指肠黏膜提取物及离体猪十二指肠血管灌流液中胆囊收缩素（CCK）的含量和分子性质。灌流液中CCK的基础浓度为84 pM当量CCK-8（平均值；范围：32 - 173 pM，n = 5）。在用氨基酸、酸化脂肪乳剂和盐酸进行腔内刺激后，浓度增加了2 - 5倍。在基础状态和刺激状态下，相关激素胃泌素的浓度均低于5 pM当量胃泌素-17。灌流液中的CCK通过使用针对生物活性C末端的抗体进行亲和层析来浓缩。随后的凝胶层析显示出一种大小与C末端十二肽（CCK-12）相似或略大的形式、一种主要类似于C末端八肽（CCK-8）的形式以及一种类似于C末端四肽（CCK-4）的形式。十二指肠黏膜中还含有CCK-33、-39以及具有更多N末端延伸的CCK肽。结果表明，小的CCK肽是主要的循环形式，而CCK-33和更大的形式是生物合成前体。
