DIFFERENT CAPACITIES FOR AMINO-ACID TRANSPORT IN PERIPORTAL AND PERIVENOUS HEPATOCYTES ISOLATED BY DIGITONIN COLLAGENASE PERFUSION
DIFFERENT CAPACITIES FOR AMINO-ACID TRANSPORT IN PERIPORTAL AND PERIVENOUS HEPATOCYTES ISOLATED BY DIGITONIN COLLAGENASE PERFUSION
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DOI：
10.1002/hep.1840090105
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发表时间：
1989-01-01
期刊：
影响因子：
13.5
通讯作者：
MECKE, D
中科院分区：
文献类型：
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作者：
BURGER, HJ;GEBHARDT, R;MECKE, D
采用地黄皂苷/胶原酶灌注法分离大鼠肝门周和静脉周肝细胞，研究与谷氨酰胺和氨代谢相关的氨基酸转运活性的腺泡异质性。对谷氨酰胺合成酶亚群的免疫细胞化学染色表明，门静脉周围亚群基本上没有谷氨酰胺合成酶阳性细胞，而静脉周围亚群显示谷氨酰胺合成酶阳性肝细胞富集2- 3倍。谷氨酰胺合成酶活性的高静脉/门静脉周围比值为59，以及其他标记酶的静脉/门静脉周围比值进一步表明门静脉周围细胞和门静脉周围细胞分离良好。-氨基异丁酸、组氨酸和谷氨酸用于测定氨基酸运输系统A、N和G-的分布模式，以及分离后1小时和原代培养期间最大激素刺激后对这些化合物的钠独立摄取。组氨酸不依赖钠的转运具有很强的异质性，其特点是较高的静脉转运率[静脉/门静脉转运比：1.5（1小时）至3.5（48小时）]，表明促进扩散可能在谷氨酰胺出口中起重要作用。相反，钠依赖性谷氨酸转运（G-系统）的异质性较强，其特点是在未受刺激的[静脉周围/门静脉周围比值：6.6（1小时）]和激素处理的静脉周围肝细胞（静脉周围/门静脉周围比值：2.2）中摄取率较高，反映了其在谷氨酰胺合成底物有效性方面的可能意义。观察到的异质性为理解与谷氨酰胺代谢相关的底物通量如何建立和调节提供了基础。此外，我们的研究结果表明，在原代培养中，门静脉周围细胞和门静脉周围细胞在氨基酸运输方面保持了至少48小时的区域特征。
Periportal and perivenous hepatocytes were isolated from rat liver by digitonin/collagenase perfusion for investigating the acinar heterogeneity of amino acid transport activities related to glutamine and ammonia metabolism. Immunocytochemical staining of the respective subpopulations for glutamine synthetase demonstrated that periportal subpopulations were essentially free of glutamine synthetase-positive cells, whereas perivenous subpopulations showed a 2- to 3-fold enrichment of glutamine synthetase-positive hepatocytes. The high perivenous/periportal ratio of 59 found for glutamine synthetase activity as well as the perivenous/periportal ratios of other marker enzymes further indicated the good separation of periportal and perivenous cells. .alpha.-Aminoisobutyric acid, histidine and glutamate were used to determine the distribution pattern of amino acid transport systems A, N and G-, as well as of the sodium-independent uptake of these compounds 1 hr after isolation and after maximal hormonal stimulation during primary culture. The strong heterogeneity of the sodium-independent transport of histidine, characterized by higher perivenous transport rates [perivenous/periportal ratio: 1.5 (1 hr) to 3.5 (48 hr)], suggests a significant role of facilitated diffusion, presumably in glutamine export. Conversely, the strong heterogeneity of the sodium-dependent glutamate transport (System G-) characterized by higher uptake rates in nonstimulated [perivenous/periportal ratio: 6.6 (1 hr)] and in hormonally treated perivenous hepatocytes (perivenous/periportal ratio: 2.2) reflects its possible significance with respect to the substrate availability for glutamine synthesis. The observed heterogeneities provide a basis for understanding how substrate fluxes related to glutamine metabolism might be established and regulated. In addition, our findings indicate that periportal and perivenous cells retain their zonal characteristics with respect to amino acid transport in primary culture for at least 48 hr.