Engelking L R, Anwer M S, Hofmann A F
Department of Medicine, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
Am J Vet Res. 1989 Apr;50(4):578-82.
The role of bile salt in biliary lipid excretion was studied in 3 healthy ponies with chronic external biliary fistulas. After endogenous bile salt pool depletion, micelle-forming taurocholate or taurochenodeoxycholate was infused to replace excreted bile salt. Enterohepatic circulations were held open (total biliary diversion) throughout each study. Results indicated that biliary lipid excretion in ponies (113 +/- 21 nmol/min/kg of body weight) is approximately 10 times less than that reported in rodents. Although the lipid composition (4.4% cholesterol, 5.6% phospholipid, and 90% bile salt) was within the predicted range for a single phase of micellar (or vesicular) liquid in solution, it was supersaturated with cholesterol because of low absolute concentrations of bile salt and phospholipid. Ponies, like guinea pigs, were determined to have a high bile salt-independent secretion of biliary lipid with little (or no) coupling to endogenous bile salt output. However, bile salt excretion induced by higher taurocholate infusion rates (ie, those greater than the physiologic range of 61 to 125 nmol/min/kg) was positively correlated with an increase in biliary phospholipid excretion, but not cholesterol excretion, thus indicating that a threshold intracellular bile salt concentration may be associated with enhanced biliary phospholipid excretion in ponies. The apparent cholerectic effects of endogenous bile salts, taurocholate, and taurochenodeoxycholate (that is, the increment in bile flow per increment in bile salt recovered) were greater in ponies than reported for any other mammal.
在3匹患有慢性外引流性胆瘘的健康小马身上研究了胆盐在胆汁脂质排泄中的作用。在内源性胆盐池耗竭后，输注形成微胶粒的牛磺胆酸盐或牛磺鹅去氧胆酸盐以替代排泄的胆盐。在每项研究中，肝肠循环均保持开放（完全胆汁转流）。结果表明，小马的胆汁脂质排泄量（113±21纳摩尔/分钟/千克体重）约为啮齿动物报道值的十分之一。尽管脂质组成（4.4%胆固醇、5.6%磷脂和90%胆盐）在溶液中单一相微胶粒（或囊泡）液体的预测范围内，但由于胆盐和磷脂的绝对浓度较低，其胆固醇处于过饱和状态。已确定小马与豚鼠一样，具有较高的不依赖胆盐的胆汁脂质分泌，与内源性胆盐输出几乎没有（或没有）关联。然而，较高牛磺胆酸盐输注速率（即大于61至125纳摩尔/分钟/千克的生理范围）诱导的胆盐排泄与胆汁磷脂排泄增加呈正相关，但与胆固醇排泄无关，因此表明细胞内胆盐浓度阈值可能与小马胆汁磷脂排泄增加有关。内源性胆盐、牛磺胆酸盐和牛磺鹅去氧胆酸盐的明显利胆作用（即每回收单位胆盐胆汁流量的增加量）在小马中比其他任何哺乳动物报道的都要大。
