Kletzien R F, Pariza M W, Becker J E, Potter V R
J Cell Physiol. 1976 Dec;89(4):641-6. doi: 10.1002/jcp.1040890421.
Amino acid transport was studied in primary cultures of parenchymal cells isolated from adult rat liver by a collagenase perfusion technique and maintained as a monolayer in a serum-free culture medium. These cells carried out gluconeogenesis from three carbon precursors (alanine, pyruvate, and lactate) in response to glucagon addition. Amino acid transport was assayed by measuring the uptake of the nonmetabolizable amino acid, alpha-aminoisobutyric acid (AIB). Addition of insulin or glucagon to culture rat liver parenchymal cells resulted in an increased influx of AIB transport. The glucocorticoid, dexamethasone, when added alone to cultures did not affect AIB transport. However, prior or simultaneous addition of dexamethasone to glucagon-treated cells caused a strong potentiation of the glucagon induction of AIB transport. Kinetic analysis of the effects of insulin and glucagon demonstrated that insulin increased the Vmax for transport without changing the Km while glucagon primarily decreased the Km for AIB transport. The effect of dexamethasone was to increase the Vmax of the low Km system.
采用胶原酶灌注技术从成年大鼠肝脏分离实质细胞，并在无血清培养基中维持单层培养，研究了这些细胞的氨基酸转运。这些细胞在添加胰高血糖素后，可利用三碳前体物质（丙氨酸、丙酮酸和乳酸）进行糖异生。通过测量不可代谢氨基酸α-氨基异丁酸（AIB）的摄取来测定氨基酸转运。向培养的大鼠肝脏实质细胞中添加胰岛素或胰高血糖素会导致AIB转运的流入增加。单独向培养物中添加糖皮质激素地塞米松不会影响AIB转运。然而，在胰高血糖素处理的细胞中预先或同时添加地塞米松会强烈增强胰高血糖素诱导的AIB转运。胰岛素和胰高血糖素作用的动力学分析表明，胰岛素增加了转运的Vmax而不改变Km，而胰高血糖素主要降低了AIB转运的Km。地塞米松的作用是增加低Km系统的Vmax。
