Robinson B S, Snoswell A M, Runciman W B, Upton R N
Biochem J. 1984 Jan 15;217(2):399-408. doi: 10.1042/bj2170399.
The net uptake and output of plasma unesterified choline, glycerophosphocholine, phosphocholine and lipid choline by organs of the conscious chronically catheterized sheep were measured. There was significant production of plasma unesterified choline by the upper- and lower-body regions and the alimentary tract and uptake by the liver, lungs and kidneys. The upper- and lower-body regions drained by the venae cavae provided the bulk (about 82%) of the total body venous return of plasma unesterified choline. Production of plasma unesterified choline by the alimentary tract was approximately balanced by the plasma unesterified choline taken up by the liver, and was almost equal to the amount of choline secreted in the bile. There was a considerable amount of glycerophosphocholine in the liver and there was production of plasma glycerophosphocholine by the liver and uptake by the lungs and kidneys. Glycerophosphocholine was higher in the plasma of sheep than in that of rats. Plasma phosphocholine was produced by the alimentary tract and kidneys. There was production of plasma lipid choline by the upper- and lower-body regions drained by the venae cavae. The results suggest that the sheep synthesizes substantial amounts of choline in ectrahepatic tissues and has the capacity for extensive retention and recycling of bile choline. These observations, coupled with a slow turnover of the endogenous choline body pool, explain the low requirement of sheep for dietary choline in contrast with non-ruminant species.
测定了清醒的长期插管绵羊各器官对血浆中非酯化胆碱、甘油磷酸胆碱、磷酸胆碱和脂质胆碱的净摄取和输出。上半身和下半身区域以及消化道可产生大量血浆非酯化胆碱，而肝脏、肺和肾脏则会摄取该物质。由腔静脉引流的上半身和下半身区域提供了全身静脉回流血浆中非酯化胆碱总量的大部分（约82%）。消化道产生的血浆非酯化胆碱与肝脏摄取的血浆非酯化胆碱大致平衡，且几乎等于胆汁中分泌的胆碱量。肝脏中存在大量甘油磷酸胆碱，肝脏可产生血浆甘油磷酸胆碱，而肺和肾脏会摄取该物质。绵羊血浆中的甘油磷酸胆碱含量高于大鼠。血浆磷酸胆碱由消化道和肾脏产生。由腔静脉引流的上半身和下半身区域可产生血浆脂质胆碱。结果表明，绵羊可在肝外组织中合成大量胆碱，并且具有广泛保留和循环利用胆汁胆碱的能力。这些观察结果，再加上内源性胆碱体池的缓慢周转，解释了与非反刍动物相比，绵羊对膳食胆碱的需求量较低的原因。
