Energy relationships between ATP synthesis and K+ gradients in cultured glial-derived cell line.
In C6 astrocytoma cells respiring with glucose, 40% of the total production of ATP was provided by glycolysis. Anaerobiosis in the presence of glucose, reduced ATP synthesis by approximately 50%, increased lactate production by 30% and caused a 3-fold decline in [creatine phosphate]/[creatine] and consequently [ATP]free[ADP]free. There was no change in [K+]i which suggests that glycolytic production of ATP provides sufficient energy to ensure normal operation of the Na+/K+ pump. In the absence of glucose, [creatine phosphate]/[creatine] declined to less than 0.1 in 15 min and there was a loss of K+ from cells. A comparison of delta GATP and delta GNa,K under aerobic conditions with and without glucose, showed the former to be larger by 1 - 2 kcal. However, under O2-limited, glucose-restricted conditions delta GATP fell below the level necessary to maintain operation of the Na+/K+ pump and led to a collapse in ionic gradients.
Ercińska
M
M
Department of Pharmacology and of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia 19104.
Silver
I A
IA
D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D001254:Astrocytoma / Q000378:metabolism; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D009457:Neuroglia / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D000255:Adenosine Triphosphate; D005947:Glucose; D011188:Potassium