Pauwels S, Dockray G J, Walker R, Marcus S
Gastroenterology. 1984 Jan;86(1):86-92.
The metabolism and some biological properties of the N-terminal 1-17 sequence of human big gastrin (G-34) were studied during infusion in 5 human volunteers. Radioimmunoassay of the 1-17 fragment in plasma indicated rapid clearance (t1/2, 2.4 min). In doses of 75-1000 pmol X kg-1 X h-1, 1-17 G-34 did not, however, influence basal acid output or G-17-stimulated acid output. Gel filtration of plasma samples taken during the infusion indicated the presence of the 1-17 fragment of G-34, together with three other immunoreactive species. Two of these correspond to N-terminal G-34 immunoreactive forms previously found in human peripheral circulation. A fourth immunoreactive component that eluted late on Sephadex G50 was identified for the first time. This component also occurred in fasting human plasma, where it was the only detectable form of N-terminal G-34 immunoreactivity; its concentration increased during infusion of 1-17 G-34. The identification of this fragment and its concentrations in human circulation after feeding deserves further study. Because the fragments of 1-17 G-34 do not occur in antral extracts, and are not produced when G-34 or its N-terminal fragments are incubated in plasma in vitro, they are presumed to be generated from the 1-17 sequence by the action of peptidases found on capillary walls. The elucidation of the mechanisms involved is essential for an understanding of the metabolic pathways of gastrin.
在5名人类志愿者输注过程中，研究了人 big 胃泌素（G-34）N端1-17序列的代谢及一些生物学特性。血浆中1-17片段的放射免疫测定表明其清除迅速（半衰期为2.4分钟）。然而，以75 - 1000 pmol·kg⁻¹·h⁻¹的剂量输注时，1-17 G-34并未影响基础酸分泌或G-17刺激的酸分泌。输注过程中采集的血浆样本经凝胶过滤显示存在G-34的1-17片段以及其他三种免疫反应性物质。其中两种与先前在人体外周循环中发现的N端G-34免疫反应形式相对应。首次鉴定出在Sephadex G50上洗脱较晚的第四种免疫反应性成分。该成分也存在于空腹人体血浆中，是N端G-34免疫反应性的唯一可检测形式；在输注1-17 G-34期间其浓度升高。该片段的鉴定及其在进食后人体循环中的浓度值得进一步研究。由于1-17 G-34的片段不存在于胃窦提取物中，且在体外将G-34或其N端片段在血浆中孵育时也不会产生，推测它们是由毛细血管壁上的肽酶作用于1-17序列产生的。阐明其中涉及的机制对于理解胃泌素的代谢途径至关重要。
