BILE-ACID TRANSPORT IN CULTURED RAT HEPATOCYTES
BILE-ACID TRANSPORT IN CULTURED RAT HEPATOCYTES
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DOI：
10.1152/ajpgi.1982.243.6.g484
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发表时间：
1982-01-01
影响因子：
--
通讯作者：
SCHARSCHMIDT, BF
中科院分区：
文献类型：
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作者：
VANDYKE, RW;STEPHENS, JE;SCHARSCHMIDT, BF
胆汁酸摄取的机制已被研究与原代单层培养的大鼠肝细胞。将肝细胞与牛磺胆酸（TC）、甘氨胆酸（GC）、胆酸（CA）、甘氨鹅脱氧胆酸（GCDC）、鹅脱氧胆酸（CDCA）、脱氧胆酸（DOCA）、石胆酸（LCA）或胆甘氨酰组胺（CCH）（一种中性胆汁酸衍生物）在含氯化钠、含1 mM哇巴因的氯化钠或氯化胆碱的培养基中孵育10 s至60 min。冲洗细胞，使其不含放射性示踪剂，定量细胞相关放射性，并计算胆汁酸摄取速率、摄取动力学参数和稳态胆汁酸含量。确定了胆汁酸摄取的两种机制。TC、GC、CA和GCDC的摄取主要通过钠依赖性、哇巴因可抑制的饱和机制发生，推测为钠偶联转运。这些胆汁酸的表观Km和Vmax估计值分别为TC、33 μ M和0.36 nmol。min-1。mg蛋白-1;气相色谱法，18 μ M和0.22 nmol . min-1。mg prot-1; CA，13 μ M和0.10 nmol . min-1。mg蛋白; GCDC，6 μ M和0.21 nmol . min-1。mg蛋白。通过这种钠偶联机制的摄取表现出相当大的底物选择性。增加环羟基化和氨基酸共轭增强，进一步与中性组胺基团（CGH）共轭降低。相反，CDCA、DOCA、LCA和CGH的摄取主要通过非饱和钠非依赖性机制（可能是简单扩散）发生。在低胆汁酸浓度下，这种机制仅占TC、GC、CA和GCDC摄取的一小部分。不饱和胆汁酸摄取率似乎与癸烷缓冲液分配系数相关，并与胆汁酸结构相关。
The mechanisms of bile acid uptake have been studied with primary monolayer cultures of rat hepatocytes. Hepatocytes were incubated with taurocholic acid (TC), glycocholic acid (GC), cholic acid (CA), glycochenodeoxycholic acid (GCDC), chenodeoxycholic acid (CDCA), deoxycholic acid (DOCA), lithocholic acid (LCA), or cholylglycylhistamine (CCH), a neutral bile acid derivative for 10 s to 60 min in medium containing sodium chloride, sodium chloride with 1 mM ouabain, or choline chloride. Cells were washed free of radioactive tracer, cell-associated radioactivity was quantitated, and bile acid uptake rates, kinetic parameters of uptake, and steady-state bile acid content were calculated. Two mechanisms for bile acid uptake were identified. Uptake of TC, GC, CA, and GCDC occurred predominantly via a sodium-dependent, ouabain-suppressible saturable mechanism, presumably sodium-coupled transport. Estimates of apparent Km and Vmax for these bile acids were TC, 33 micro M and 0.36 nmol . min-1 . mg prot-1; GC, 18 micro M and 0.22 nmol . min-1 . mg prot-1; CA, 13 micro M and 0.10 nmol . min-1 . mg prot; and GCDC, 6 micro M and 0.21 nmol . min-1 . mg prot, respectively. Uptake via this sodium-coupled mechanism exhibited considerable substrate selectivity. It was enhanced by increased ring hydroxylation and amino acid conjugation and decreased by further conjugation with a neutral histamine group (CGH). In contrast, uptake of CDCA, DOCA, LCA, and CGH occurred primarily via a nonsaturable sodium-independent mechanism, possibly simple diffusion. This mechanism accounted for only a small portion of uptake of TC, GC, CA, and GCDC at low bile acid concentrations. Nonsaturable bile acid uptake rates appeared to correlate with decane-buffer partition coefficients and to be related to bile acid structure.