Uptake and metabolism of putrescine in confluent LLC-PK1 cells.
Uptake and metabolism of putrescine in confluent LLC-PK1 cells.
复制标题
汇合的 LLC-PK1 细胞中腐胺的摄取和代谢。
DOI：
10.1152/ajpcell.1990.259.1.c84
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Cook,JS
中科院分区：
文献类型：
--
作者：
Hauser,MR;Cook,JS
腐胺通过Na（+）依赖性和Na（+）非依赖性途径以大致相等的速率被汇合的猪肾（LLC-PK 1）细胞摄取。前者对1 mM阿米洛利敏感，而后者不敏感。顶面和基底面的摄取率相似。腐胺的主要归宿是氧化脱氨基，产生的产物似乎是γ-氨基丁醛或δ 1-吡咯啉。剩余的大部分转化为暂时鉴定为亚精胺、精胺或另一种未鉴定产物的产物;这些产物以及腐胺本身从细胞的任一表面损失。在6.8-8.0范围内改变细胞外pH对腐胺摄取没有影响。酸化至细胞内pH 6.8的细胞显示出掺入放射性的能力降低，这一效应可能是由于抑制二胺氧化酶所致。用2-脱氧-D-葡萄糖和NaN 3处理细胞耗尽ATP储存不会减少腐胺摄取，表明该机制不是主要的活性转运蛋白。5-50 μ M Hg 2+以剂量依赖性方式抑制Na（+）依赖性摄取组分。高浓度（500- 1，000 μ M）的对氯汞苯磺酸（p-CMBS）不影响Na（+）非依赖性摄取，但在存在Na+的情况下，比单独消耗Na+更能抑制总摄取，这表明Na+增强了p-CMBS与两种转运蛋白的结合。亚精胺和精胺与腐胺竞争吸收，但其他各种有机碱和氨基酸不竞争吸收，这表明多胺的转运机制与其他化合物的转运机制不同。
Putrescine is taken up by confluent pig kidney (LLC-PK1) cells at roughly equal rates over both Na(+)-dependent and Na(+)-independent pathways. The former is sensitive to 1 mM amiloride, but the latter is not. Uptake rates are similar at both the apical and basolateral surfaces. The principal fate of the putrescine is oxidative deamination, yielding a product that appears to be either gamma-aminobutyraldehyde or delta 1-pyrroline. Most of the remainder is converted to products tentatively identified as spermidine, spermine, or another unidentified product; these products as well as putrescine itself are lost from the cell at either surface. Changing the extracellular pH in the range of 6.8-8.0 has no affect on putrescine uptake. Cells acidified to intracellular pH 6.8 show a reduced capacity to incorporate radioactivity, an effect that may be due to inhibition of diamine oxidase. Depletion of ATP stores by treating cells with 2-deoxy-D-glucose and NaN3 does not reduce putrescine uptake, suggesting that the mechanism is not a primary active transporter. The Na(+)-dependent component of uptake is inhibited by 5-50 microM Hg2+ in a dose-dependent manner. p-Chloromercuribenzene sulfonic acid (p-CMBS) at high concentrations (500-1,000 microM) does not affect Na(+)-independent uptake but in the presence of Na+ depresses total uptake more than Na+ depletion alone, suggesting that Na+ enhances the binding of p-CMBS to both transporters. Spermidine and spermine compete with putrescine for uptake, but a variety of other organic bases and amino acids do not, indicating that polyamines are transported by mechanisms distinct from the transporters for those other compounds.