Pentose pathway of glucose metabolism in isolated granular pneumocytes. Metabolic regulation and stimulation by paraquat.
Pentose pathway of glucose metabolism in isolated granular pneumocytes. Metabolic regulation and stimulation by paraquat.
复制标题
分离颗粒肺细胞中葡萄糖代谢的戊糖途径。
DOI：
10.1016/0006-2952(84)90191-6
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发表时间：
1984
影响因子：
5.8
通讯作者：
Reicherter,J
中科院分区：
文献类型：
--
作者：
Fisher,AB;Reicherter,J
葡萄糖代谢的戊糖磷酸途径的活性在分离的颗粒肺细胞中在已知在完整肺中改变该途径的各种代谢条件下测量。通过大鼠肺的胰蛋白酶消化分离颗粒肺细胞，并在使用前在原代培养物中保持24小时。将细胞在37 ° C下与5.5 mM葡萄糖（专门标记为1 - 14 C、6 - 14 C、U-14 C或5 - 3 H）孵育1小时，以测定葡萄糖利用率、戊糖循环活性以及线粒体和戊糖途径之间CO2产生的分配。对于对照细胞，总葡萄糖利用率为111 ± 4.8 nmoles·hr-1·（106个细胞）-1（平均值± S.E.，N = 19），和2.2%的戊糖循环代谢。戊糖循环CO2产量为7.3 nmoles·hr − 1·（106 cells）− 1，占总CO2产量的34%。二硝基苯酚（50 μ M）刺激线粒体CO2产生5倍，但对戊糖循环活性无影响。吩嗪硫酸甲酯（5 μ M）对线粒体活性没有影响，但刺激戊糖循环活性15倍。抗霉素A（0.4 μ g/ml）对两条通路均有明显抑制作用。在用百草枯（3 mM）预孵育30 min后，戊糖循环CO2产量增加到107 nmoles·hr − 1·（106个细胞）− 1，占葡萄糖利用率的39.6%和CO2产量的88.4%。百草枯对线粒体CO2的产生没有影响。这些研究表明，戊糖循环在静息颗粒肺细胞占一个主要部分的CO2生产从葡萄糖和该途径的活性是由细胞质还原当量的利用率进行调节。百草枯可显著刺激颗粒肺细胞的戊糖循环活性，从而最大限度地利用细胞质NADPH。
Activity of the pentose phosphate pathway of glucose metabolism was measured in isolated granular pneumocytes under a variety of metabolic conditions known to alter this pathway in intact lungs. Granular pneumocytes were isolated by trypsinization of rat lungs and maintained in primary culture for 24 hr before use. Cells were incubated for 1 hr at 37° with 5.5 mM glucose specifically labeled as 1-14C, 6-14C, U-14C, or 5-3H for determination of glucose utilization, pentose cycle activity, and partition of CO2production between mitochondrial and pentose pathways. With control cells, total glucose utilization was 111 ± 4.8 nmoles · hr−1· (106cells)−1(mean ± S.E., N = 19), and 2.2% was metabolized by the pentose cycle. Pentose cycle CO2production was 7.3 nmoles · hr−1· (106cells)−1representing 34% of total CO2production. Dinitrophenol (50μM) stimulated mitochondrial CO2production 5-fold but had no effect on the pentose cycle activity. Phenazine methosulfate (5 μM) had no effect on mitochondrial activity but stimulated pentose cycle activity 15-fold. Antimycin A (0.4 μg/ ml) markedly inhibited both pathways. After a 30-min preincubation with paraquat (3 mM), the pentose cycle CO2production increased to 107 nmoles · hr−1· (106cellls)−1accounting for 39.6% of glucose utilization and 88.4% of CO2production. Mitochondrial CO2production was unchanged with paraquat. These studies demonstrate that the pentose cycle in resting granular pneumocytes accounts for a major fraction of the CO2production from glucose and that activity of this pathway is regulated by the utilization of cytoplasmic reducing equivalents. Paraquat produces marked stimulation of pentose cycle activity in granular pneumocytes, resulting in maximal utilization of cytoplasmic NADPH.