Brachet P, Prévoteau H, Mathé V, Tomé D
Unité de Nutrition Humaine et Physiologie Intestinale de I'INRA, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France.
Digestion. 1996;57(5):374-81. doi: 10.1159/000201361.
Fasting and refeeding dramatically alter small intestinal mucosal growth which is greatly dependent on polyamine biosynthesis and transport. The aim of this study was therefore to examine the uptake of the diamine putrescine by brush-border membrane vesicles from the small intestine of rats fasted for 3 days or refed a standard diet after a PERIOD OF FASTING. WHILE THE MICHAELIS-MENTEN CONSTANT KM WAS essentially unaltered, the maximum velocity (Vmax) for putrescine uptake was 1.85-fold higher in fasted animals than in ad libitum-fed controls. Refeeding fasted rats for 24 h caused a 31% decrease in the Vmax value that, however, remained 1.27-fold higher than in control RATS, WHILE THE KM VALUE WAS STILL UNCHANGED. FASTING RATS OR refeeding rats after a period of fasting caused only a 13 or 17% increase, respectively, in the value of the constant for the nonsaturable component (P) of putrescine transport relative to the corresponding control condition. Our study also confirms that both the mucosal polyamine biosynthesis and intestinal content are altered by fasting. We suggest that an increased uptake activity may have a conservative role by preventing a substantial loss of tissue polyamines during fasting.
禁食和重新喂食会显著改变小肠黏膜生长，而小肠黏膜生长很大程度上依赖于多胺的生物合成和转运。因此，本研究的目的是检测禁食3天的大鼠小肠刷状缘膜囊泡对二胺腐胺的摄取情况，以及禁食一段时间后重新喂食标准饮食的大鼠小肠刷状缘膜囊泡对二胺腐胺的摄取情况。虽然米氏常数Km基本未变，但禁食动物对腐胺摄取的最大速度（Vmax）比自由进食的对照动物高1.85倍。禁食大鼠重新喂食24小时后，Vmax值下降了31%，但仍比对照大鼠高1.27倍，而Km值仍未改变。禁食大鼠或禁食一段时间后重新喂食的大鼠，其腐胺转运非饱和成分（P）的常数相对于相应对照条件分别仅增加了13%或17%。我们的研究还证实，禁食会改变黏膜多胺的生物合成和肠道含量。我们认为，摄取活性的增加可能通过防止禁食期间组织多胺的大量流失而起到保守作用。
