Aldini R, Roda A, Lenzi P L, Ussia G, Vaccari M C, Mazzella G, Festi D, Bazzoli F, Galletti G, Casanova S
Istituto di Scienze Chimiche, Università di Bologna, Italy.
Eur J Clin Invest. 1992 Nov;22(11):744-50. doi: 10.1111/j.1365-2362.1992.tb01439.x.
The intestinal absorption of bile acids (BA) with different chemical structure has been evaluated in the rabbit, after intestinal infusion of different concentrations (0.25-30 mM) of BA, by mesenteric blood sampling. Cholic (CA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA) acid, free and taurine (T-) conjugated, together with glycocholic (GCA) acid and deoxycholic acid (DCA) were studied. The apparent uptake parameters were calculated. All conjugated BA showed active transport (T max, nmol min-1 cm-1 int.), with Tmax values in the following order: TCA > TUDCA > TCDCA; unconjugated BA showed passive uptake, with values in the following order: DCA > CDCA > UDCA > CA. GCA and CA showed both passive uptake and active transport. For all BA studied the % uptake in the ileal segment considered was less than 10%, BA uptake being thus limited by transport and/or diffusion kinetics, rather than by flow velocity. The liquid resistance to BA radial diffusion inside the lumen was evaluated, and the infusate-to-blood uptake parameters corrected for it, in order to get the uptake parameters from the epithelium-to-liquid interface to mesenteric blood: the apparent Km decreased, passive uptake coefficient increased, while Tmax was unchanged. The passive component of the uptake, corrected for the luminal resistance, correlated with the BA hydrophobicity (r = 0.963; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
通过肠系膜采血，在兔体内肠内输注不同浓度（0.25 - 30 mM）的胆汁酸（BA）后，评估了具有不同化学结构的胆汁酸的肠道吸收情况。研究了胆酸（CA）、鹅去氧胆酸（CDCA）、熊去氧胆酸（UDCA），游离型和牛磺酸（T -）结合型，以及甘氨胆酸（GCA）和脱氧胆酸（DCA）。计算了表观摄取参数。所有结合型胆汁酸均显示出主动转运（Tmax，nmol min-1 cm-1 int.），Tmax值顺序如下：TCA > TUDCA > TCDCA；非结合型胆汁酸显示出被动摄取，其值顺序如下：DCA > CDCA > UDCA > CA。GCA和CA既显示出被动摄取又显示出主动转运。对于所有研究的胆汁酸，在所考虑的回肠段中的摄取百分比均小于10%，因此胆汁酸的摄取受转运和/或扩散动力学限制，而非流速限制。评估了管腔内胆汁酸径向扩散的液体阻力，并对注入液到血液的摄取参数进行校正，以获得从上皮细胞到液体界面再到肠系膜血液的摄取参数：表观Km降低，被动摄取系数增加，而Tmax不变。校正管腔阻力后的摄取被动成分与胆汁酸疏水性相关（r = 0.963；P < 0.01）。（摘要截断于250字）
