AT PHYSIOLOGIC ALBUMIN OLEATE CONCENTRATIONS OLEATE UPTAKE BY ISOLATED HEPATOCYTES, CARDIAC MYOCYTES, AND ADIPOCYTES IS A SATURABLE FUNCTION OF THE UNBOUND OLEATE CONCENTRATION - UPTAKE KINETICS ARE CONSISTENT WITH THE CONVENTIONAL THEORY
AT PHYSIOLOGIC ALBUMIN OLEATE CONCENTRATIONS OLEATE UPTAKE BY ISOLATED HEPATOCYTES, CARDIAC MYOCYTES, AND ADIPOCYTES IS A SATURABLE FUNCTION OF THE UNBOUND OLEATE CONCENTRATION - UPTAKE KINETICS ARE CONSISTENT WITH THE CONVENTIONAL THEORY
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DOI：
10.1172/jci114301
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发表时间：
1989-10-01
影响因子：
15.9
通讯作者：
BERK, PD
中科院分区：
文献类型：
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作者：
SORRENTINO, D;ROBINSON, RB;BERK, PD
为了重新检查白蛋白在长链脂肪酸的细胞摄取中的作用，我们测量了分离的肝细胞、脂肪细胞和心肌细胞在含有油酸/白蛋白复合物的摩尔比为0.01:1至2:1的孵育过程中对[3H]油酸的摄取。对于每个比例的摄取研究了在广泛的白蛋白浓度范围内。在所有三种细胞类型中，在任何给定的油酸/白蛋白比下，随着油酸和白蛋白复合物浓度的增加，摄取似乎是饱和的，尽管每个摩尔比下未结合的油酸浓度基本上是恒定的。然而，这些赝饱和曲线的“Km”受底物有效性的影响，而“Vmax”不受影响。在低白蛋白浓度下，摄取速度与未结合油酸浓度无关。然而，观察到的和预期的摄取速度在白蛋白浓度接近生理水平时是一致的，并且是油酸/白蛋白比率和由此产生的未结合油酸浓度的饱和函数。因此，在本研究中使用多种悬浮细胞类型的实验条件下，油酸摄取动力学与生理白蛋白浓度下的传统理论一致。
To reexamine the role of albumin in cellular uptake of long chain fatty acids, we measured [3H]oleate uptake by isolated hepatocytes, adipocytes, and cardiac myocytes from incubations containing oleate/albumin complexes at molar ratios from 0.01:1 to 2:1. For each ratio the uptake was studied over a wide range of albumin concentrations. In all three cell types and at any given oleate/albumin ratio, the uptake appeared saturable with increasing concentrations of oleate:albumin complexes despite the fact that the unbound oleate concentration for each molar ratio is essentially constant. However, the "Km" but not the "Vmax" of these pseudosaturation curves was influenced by substrate availability. At low albumin concentrations, uptake velocities did not correlate with unbound oleate concentrations. However, observed and expected uptake velocities coincided at albumin concentrations approaching physiologic levels and were a saturable function of the oleate/albumin ratios and the consequent unbound oleate concentrations employed. Hence, under the experimental conditions employed in this study using a variety of suspended cell types, oleate uptake kinetics were consistent with the conventional theory at physiologic concentrations of albumin.