Holst Pedersen J, Fahrenkrug J
Peptides. 1986 Jan-Feb;7(1):15-20. doi: 10.1016/0196-9781(86)90054-9.
Feeding responses and day and night levels of plasma concentration of neurotensin (NT) and NT-fragments were studied in healthy subjects. Plasma levels were measured by three radioimmunoassays recognizing intact NT in addition to C- and N-terminal immunoreactivity. The metabolism of NT was studied following intravenous administration. In 106 subjects fasting levels of intact NT (median 18 pmol/l), C-terminal (median 30 pmol/l) and N-terminal immunoreactivity (median 95 pmol/l) were unrelated to sex or age. Postprandially plasma levels in seven subjects measured with all assays increased by a factor 1-3. Following a mixed meal the increase was biphasic, whereas the response to dairy cream was monophasic. Repetitive measurements during 24 hours showed that levels of N-terminal immunoreactivity fluctuated in a manner related to meal ingestion and were elevated throughout the daytime, whereas intact NT and C-terminal immunoreactivity changed little. Following intravenous infusion of 2.4 pmol/kg/min NT in 5 subjects the chromatographic pattern was similar to that seen postprandially. The plasma half life of intact NT and C-terminal immunoreactivity was 1.5 and 1.2 min, whereas that of N-terminal immunoreactivity was 10.0 min. The differences in circulating levels could be explained by these differences in metabolism, but the physiological significance remains to be elucidated.
在健康受试者中研究了神经降压素（NT）及其片段的进食反应以及血浆浓度的昼夜水平。除了C端和N端免疫反应性外，还通过三种识别完整NT的放射免疫测定法测量血浆水平。静脉给药后研究了NT的代谢。在106名受试者中，完整NT（中位数18 pmol/l）、C端（中位数30 pmol/l）和N端免疫反应性（中位数95 pmol/l）的空腹水平与性别或年龄无关。在用所有测定法测量的7名受试者中，餐后血浆水平升高了1至3倍。进食混合餐后，升高呈双相性，而对乳脂的反应呈单相性。24小时内的重复测量表明，N端免疫反应性水平以与进餐摄入相关的方式波动，并且在整个白天都升高，而完整NT和C端免疫反应性变化不大。在5名受试者中静脉输注2.4 pmol/kg/min NT后，色谱图与餐后所见相似。完整NT和C端免疫反应性的血浆半衰期分别为1.5分钟和1.2分钟，而N端免疫反应性的血浆半衰期为10.0分钟。循环水平的差异可以用这些代谢差异来解释，但其生理意义仍有待阐明。
