Effect of oxygen and glucose availability on the glycolytic rate in neuroblastoma cells under different conditions of culture.
Neuroblastoma cells, cultivated on plastic dishes, in presence of 15 mM glucose resist very well to hypoxia. Cells incubated on plastic dishes, if left unshaken, showed a Pasteur effect at an oxygen concentration below 10%. Oxygen diffusion was the limiting factor in these plastic dishes since improved oxygen diffusion, as a result of shaking, decreased the lactate production considerably at all oxygen concentrations used. When cells were cultivated on Petriperm((R)) dishes, coated with polylysine, oxygen diffusion was no longer a rate-limiting factor: less lactate was produced at 21% O(2) and hypoxia, down to 2.5% O(2) did not show any increase in the rate of lactate production, while Antimycin A drastically increased the glycolytic rate. A situation of limited oxygen availability resulted in two different kinds of adaptation of the neuroblastoma cells: first an instantaneous metabolic regulation leading to an increased glycolytic rate-the Pasteur effect-followed later by an increase in the activities of the glycolytic enzymes-hexokinase (EC 2.7.1.1), phosphoglucose isomerase (EC 5.3.1.9), 6-phosphofructokinase (EC 2.7.1.11), pyruvate kinase (EC 2.7.1.40) and lactate dehydrogenase (EC 1.1.1.27) and a simultaneous decrease of the mitochondrial cytochrome c oxidase (EC 1.9.3.1) activity. However, when the glucose concentration in the medium was decreased to 5 mM the cells were affected by hypoxia already at 5% O(2): cells released lactate dehydrogenase extracellularly and their protein content was decreased. This toxic effect of hypoxia was related to the exhaustion of the glucose supply.
Pauwels
P J
PJ
International Institute of Cellular and Molecular Pathology and University of Louvain, avenue Hippocrate, 75, B 1200 Brussels, Belgium.
Opperdoes
F R
FR
Trouet
A
A