Just W W, Schimassek H
Eur J Cell Biol. 1980 Oct;22(2):649-53.
Polyamines are associated with fundamental metabolic and functional steps in cell metabolism. The activity of ornithine decarboxylase, the key enzyme in polyamine metabolism, was followed during the preparation of rat liver parenchymal cells and in the isolated cells during incubation. In experiments in which ornithine decarboxylase was not induced in vivo, enzyme activity dropped to barely measurable values during the preparation. An even more drastic loss of enzyme activity was noted in livers in which ornithine decarboxylase activity was stimulated in vivo 20-40fold by previous injection of bovine growth hormone, or thioacetamide or elevated because of circadian rhythmical changes of the enzyme activity. Within the first 20 min of liver perfusion to disintegrate the tissue, ornithine decarboxylase activity decreased by up to 80%. The presence of bovine growth hormone during cell preparation cannot prevent the loss of enzyme activity. Incubation of the isolated cells for periods of up to 240 min did not restore the enzyme activity. Furthermore, incubation of the cells with bovine growth hormone did not induce ornithine decarboxylase, even though the medium was supplemented with amino acids in physiological concentrations. During normal liver perfusion and in contrast to the situation with isolated cells, there is no loss of enzyme activity but a small rise. Following pretreatment of the animals with bovine growth hormone or thioacetamide the highly stimulated activity of ornithine decarboxylase declined slowly during liver perfusion, but never dropped to values lower than normal for perfusion periods of up to 240 min. Moreover, in the intact perfused organ ornithine decarboxylase remains responsive to bovine growth hormone. The experiments demonstrate that enzymatic tissue dispersion by collagenase in particular or the preparation of isolated cells in general drastically alters the metabolic and functional state of rat liver parenchymal cells.
多胺与细胞代谢中的基本代谢和功能步骤相关。在大鼠肝实质细胞制备过程以及分离细胞孵育期间，对多胺代谢的关键酶鸟氨酸脱羧酶的活性进行了跟踪。在体内未诱导鸟氨酸脱羧酶的实验中，该酶活性在制备过程中降至几乎无法测量的值。在先前注射牛生长激素、硫代乙酰胺使鸟氨酸脱羧酶活性在体内被刺激20 - 40倍，或由于酶活性的昼夜节律变化而升高的肝脏中，观察到酶活性有更显著的损失。在肝脏灌注以分解组织的最初20分钟内，鸟氨酸脱羧酶活性下降高达80%。细胞制备过程中存在牛生长激素并不能阻止酶活性的损失。将分离的细胞孵育长达240分钟也未能恢复酶活性。此外，即使培养基中添加了生理浓度的氨基酸，用牛生长激素孵育细胞也不会诱导鸟氨酸脱羧酶。与分离细胞的情况相反，在正常肝脏灌注期间，酶活性没有损失反而略有上升。在用牛生长激素或硫代乙酰胺对动物进行预处理后，肝脏灌注期间鸟氨酸脱羧酶受到高度刺激的活性缓慢下降，但在长达240分钟的灌注期内从未降至低于正常的值。此外，在完整的灌注器官中，鸟氨酸脱羧酶仍然对牛生长激素有反应。这些实验表明，特别是通过胶原酶进行的酶促组织分散或一般的分离细胞制备会极大地改变大鼠肝实质细胞的代谢和功能状态。
