69.犬貓罹患下列何項肝病，會以乳果糖（lactulose）液口服來治療？
(A)嗜中性球性膽管炎
(B)淋巴球性膽管炎
(C)膽道阻塞
(D)肝門脈分流

乳果糖與可溶纖維可降低氨的代謝，經由結腸細菌叢代謝產出的酸可降低結腸內的pH值。氨以離子型態呈現(鹼在酸容易排出)，因此不被吸收經由糞便排出

分享先前小內上課筆記 註: 當初僅是為了對付期中期末考因此寫得很隨便 請見諒

The Mechanism of Action of Lactulose/ 詳細的乳果糖運作機制
Lactulose reduces intestinal ammonia production and absorption in three ways.
First, the colonic metabolism of sugars causes a laxative effect via an increase in intraluminal gas formation and osmolality which leads to a reduction in transit time and intraluminal pH. This laxative effect is also beneficial for constipation.
Next, lactulose promotes increased uptake of ammonia by colonic bacteria which utilize the trapped colonic ammonia as a nitrogen source for protein synthesis. The reduction of intestinal pH facilitates this process, which favors the conversion of ammonia (NH3) produced by the gut bacteria, to ammonium (NH4+), an ionized form of the molecule, unable to cross biological membranes.
Finally, lactulose also causes a reduction in intestinal production of ammonia. The acidic pH destroys urease-producing bacteria involved in the production of ammonia.  The unabsorbed disaccharide also inhibits intestinal glutaminase activity, which blocks the intestinal uptake of glutamine, and its metabolism to ammonia.

有點懶得翻譯
1. 滲透性瀉藥-->減少腸內運輸時間以及降低pH
2. 乳果糖促進腸內細菌利用NH3 for蛋白質合成的氮來源,低pH也會促進腸內細菌把NH3會轉變成NH4+,而NH4+是無法穿過細胞膜的,會留在腸內
3. 最後,乳果糖會降低腸道產生的MH3,因為低pH會破壞製造NH3的urease-producing bacteria,而無法吸收的雙醣也會減低腸道內麩胺酸酶(glutaminase)活動,阻斷麩醯胺酸(glutamine)的吸收,也就等於麩醯胺酸(glutamine)代謝成NH3

Source: https://www.ncbi.nlm.nih.gov/books/NBK536930/