KINETICS OF GLUCOSE-TRANSPORT IN HUMAN-ERYTHROCYTES
KINETICS OF GLUCOSE-TRANSPORT IN HUMAN-ERYTHROCYTES
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DOI：
10.1113/jphysiol.1983.sp014720
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发表时间：
1983-01-01
影响因子：
5.5
通讯作者：
BRAHM, J
中科院分区：
文献类型：
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作者：
BRAHM, J
用MilliPore-Swinnex过滤技术和快速连续流管技术测定了人红细胞在自交换和净外排条件下的D-[14C]葡萄糖单向外流速率，该技术可在几分之一秒内测量初始速率。38度、25度和10度的测定。葡萄糖自交换通量和净外排的浓度依赖关系表明，在所有温度下，自交换和净外排均遵循简单的Michaelis-Menten动力学。在38度。C最大自交换通量和最大净外排相同(6次。10-10mol/cm2·cntdo.5)。半最大流量(K1/2)时细胞内葡萄糖浓度自交换为6.7 mM，净流出为8.2 mM。随着温度的降低，最大葡萄糖自交换通量逐渐超过最大净外排，在10℃时约为最大净外排的3倍。自交换的C.K1/2在10度时增加到12.6 mm。C，而净排出的K1/2降至4.4 mm。在38度。当胞外葡萄糖浓度为40 mM时，葡萄糖自交换时的通透性在pH=6和pH=9之间呈钟形关系，在pH=7.2时达到最大值，而表观渗透系数在pH=6和pH=9时都降低了一半。葡萄糖转运的温度依赖性在47~0度之间。在细胞葡萄糖浓度为100 mM时，保证了葡萄糖转运系统在温度范围内85%的饱和度。葡萄糖转运的Arrhenius活化能不是恒定的。在38~47℃范围内，随着温度的降低，净流出的活化能从55kJ/mol逐渐增大。C至151kJ/mol，范围为0~10℃。C.自交换通量随温度的变化在10℃左右变化较明显。结果表明，Arrhenius活化能在10℃以上为61kJ/mol，在10℃以下为120kJ/mol。C。
The rate of unidirectional D-[14C]glucose efflux from human red blood cells was determined at self-exchange and net efflux conditions by means of the Millipore-Swinnex filtering technique and the rapid continuous flow tube technique with which initial rates can be measured within fractions of a second. Determinations at 38, 25 and 10.degree. C of the concentration dependence of glucose self-exchange flux and net efflux showed that both self exchange and net efflux followed simple Michaelis-Menten kinetics at all tmperatures. At 38.degree. C the maximal self-exchange flux and the maximal net efflux were identical (6 .times. 10-10 mol/cm2 .cntdot. 5). The cellular glucose concentration for half-maximal flux (K 1/2) was 6.7 mM for self exchange and 8.2 mM for net efflux. By lowering temperature the maximal glucose self-exchange flux progressively exceeded the maximal net efflux, and was about 3 times larger at 10.degree. C. K1/2 for self exchange increased to 12.6 mM at 10.degree. C, while K1/2 for net efflux decreased to 4.4 mM. At 38.degree. C the glucose permeability at self exchange at a constant extracellular glucose concentration of 40 mM showed a bell-shaped pH dependence betwen pH 6 and pH 9. A maximum was found at pH 7.2, whereas the apparent permeability coefficient was halved both at pH 6 and pH 9. The temperature dependence of glucose transport was determined between 47 and 0.degree. C at a cellular glucose concentration of 100 mM which ensured > 85% saturation of the glucose transport system within the temperature range. The Arrhenius activation energy of glucose transport was not constant. By lowering the temperature the activation energy increased gradually for net effux from 55 kJ/mol between 38 and 47.degree. C to 151 kJ/mol between 0 and 10.degree. C. The temperature dependence of self-exchange flux showed a more pronounced change around 10.degree. C. The Arrhenius activation energy was found to be 61 kJ/mol above and 120 kJ/mol below 10.degree. C.