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首页> 外文期刊>The biochemical journal >Control by amino acids of the activity of system A-mediated amino acid transport in isolated rat hepatocytes
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Control by amino acids of the activity of system A-mediated amino acid transport in isolated rat hepatocytes

机译：氨基酸对分离的大鼠肝细胞中介导的氨基酸输送活性的氨基酸

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pThe effect of amino acids, in concentrations corresponding to those found in the portal vein of rats given a high-protein diet, was investigated on the activity of system A amino acid transport in hepatocytes from fed rats. Amino acids counteracted the induction of system A by insulin or glucagon. This effect was observed at all concentrations of hormones tested, up to 1 microM. Amino acids did not affect the basal cyclic AMP concentration in hepatocytes, or the large rise in cyclic AMP elicited by glucagon. The reversal of system-A induction was observed at relatively low concentration of amino acids, corresponding to plasma values reported in rats given a basal diet. Amino acids were separately tested: substrates of system A were particularly efficient, but so were glutamine and histidine. Non-metabolizable substrates of system A, such as 2-aminoisobutyrate, were also inhibitory, suggesting that a part of the effect of amino acids is independent of their cellular metabolism. Provision of additional energy substrates such as lactate and oleate did not affect induction of system A or the inhibitory effects of amino acids. Thus amino acids do not act by serving as an energy source and by maintaining the integrity of hepatocytes. Inhibition of mRNA synthesis by actinomycin practically abolished the effect of amino acids on the induction of system A by glucagon. The results suggest that amino acids may promote the synthesis of protein(s) affecting the activity of system A either directly at the carrier unit or at an intermediate stage of its emergence./p
机译：氨基酸的效果，在对应于大鼠门静脉中发现的浓度的浓度，研究了喂养大鼠肝细胞中氨基酸输送的活性。氨基酸通过胰岛素或胰高血糖素抵消了系统A的诱导。在测试的所有浓度的激素中观察到这种效果，高达1微米。氨基酸不会影响肝细胞中的基础环状AMP浓度，或者胰高血糖素引发的循环放大器的大升高。系统 - 在相对低浓度的氨基酸中观察到诱导的逆转，对应于赋予基础饮食的大鼠中报告的血浆值。氨基酸被单独测试：系统A的底物特别有效，但谷氨酰胺和组氨酸也是如此。诸如2-氨基异丁酸的系统A的不可代谢底物也是抑制作用，表明氨基酸的一部分效果与其细胞代谢无关。提供额外的能量底物，例如乳酸和油eee不影响系统A或氨基酸的抑制作用的诱导。因此，氨基酸不能用作能量来源并通过维持肝细胞的完整性来作用。通过放线菌素的mRNA合成的抑制几乎废除了氨基酸对胰高血糖素诱导氨基酸的影响。结果表明，氨基酸可以促进蛋白质的合成，这些蛋白质可以直接在载体单元处或其出现的中间阶段。

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