Uptake and metabolism of fatty acids and analogues by cultured cardiac cells from chick embryo.
Uptake and metabolism of fatty acids and analogues by cultured cardiac cells from chick embryo.
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DOI：
10.1111/j.1432-1033.1976.tb10338.x
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发表时间：
1976-05
期刊：
影响因子：
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通讯作者：
Denise Samuel;Sonia Paris;Gérard Ailhaud
中科院分区：
文献类型：
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作者：
Denise Samuel;Sonia Paris;Gérard Ailhaud
来自鸡胚的培养心肌细胞在基本培养基中呈融合单层生长，会摄取与血清白蛋白结合的标记脂肪酸（从C6到C22），并迅速掺入中性脂质和复合脂质中（15秒时可见），而β -氧化则延迟（15分钟时可见）。脂肪酸通过两种机制进入心肌细胞，一种涉及易饱和过程，另一种类似于被动扩散。可饱和转运系统以高亲和力识别脂肪酸，Km值为4.5到16μM。V值为每分钟每（10⁶个细胞）掺入0.03到0.3纳摩尔脂肪酸。脂肪酸之间存在竞争性抑制，而葡萄糖、氨基酸和乳酸不与棕榈酸竞争进入细胞。对来自常规培养基和细胞的未酯化脂肪酸的分析显示浓度梯度高达54倍；此外，在20℃的基本培养基中进行的实验表明，脂肪酸在细胞内积累高达28倍。在20℃使细胞负载后可测量流出速率；曲线呈双峰型，由此确定的伪一级速率常数约为0.5 min⁻¹，而根据流入速率计算的被动扩散成分的速率常数为2.5到5.0 min⁻¹。对血清白蛋白在恒定和可变脂肪酸 - 白蛋白摩尔比下作用的研究表明，摄取速率由总脂肪酸浓度控制，而不仅仅由未结合脂肪酸的浓度控制。未发现标记脂肪酸与假定含有脂肪酸结合蛋白的细胞质部分结合；我们的结果支持在亚细胞器水平或更可能在心肌细胞表面存在脂肪酸特异性转运系统。
Cultured heart cells from chick embryo, present as a confluent monolayer in a minimal medium, take up labelled fatty acids (from C6 to C22) bound to serum albumin with a rapid incorporation into neutral and complex lipids (visible at 15 s), while beta-oxidation is delayed (visible at 15 min). Fatty acids enter the cardiac cells through two mechanisms, one involving a readily saturable process, the other resembling passive diffusion. The saturable transport system recognizes fatty acids with a high affinity, Km from 4.5 to 16 muM. The V is from 0.03 to 0.3 nmol of fatty acid incorporated min-1 (10(6) cells)-1. Competitive inhibition occurs between fatty acids while glucose, aminoacids and lactate do not compete with palmitate for the entry into the cells. The analysis of unesterified fatty acids from the usual culture medium and from the cells show a gradient of concentration up to 54-fold; moreover experiments performed in minimal medium at 20 degrees C show that fatty acids accumulate up to 28-fold in the cells. Efflux rates can be measured after loading the cells at 20 degrees C; the curves are bimodal and the pseudo first-order rate constants thus determined are in the order of 0.5 min-1, as opposed to 2.5 to 5.0 min-1 for the passive-diffusion component calculated for the influx rates. Studies on the role of serum albumin at constant and at variable fatty acid-albumin molar ratios indicate that the rate of uptake is controlled by the total fatty acid concentration and not solely by the concentration of unbound fatty acids. No labelled fatty acid was found to be bound to the cytoplasmic fraction supposed to contain the fatty acids-binding protein; our results are in favour of the presence of a specific transport system for fatty acids either at the level of subcellular organelles or more likely at the surface of cardiac cells.