The effect of pH on glycolysis and phosphofructokinase activity in cultured cells and synaptosomes.
The effect of [H+] on the rate of glycolysis was investigated in glioma C6 and fibroblast BHK-21 cells and in synaptosomes from rat brain. The rates of lactate production at an extracellular pH (pHe) of 6.2, 7.4, and 7.8 were correlated with intracellular [ATP], [ADP], and [P(i)] ([ATP]i, [ADP]i, and [P(i)]i, respectively) and, when relevant, creatine phosphate (PCr) as well as with the levels of several glycolytic intermediates. In C6 cells cytosolic [H+] was measured simultaneously together with [Ca2+], [K+], [Na+], and membrane potentials. In all three systems studied, an increase in [H+]e suppressed whereas a fall enhanced the rate of lactate generation. Changes in pHe produced no simple correlation between the amount of lactate formed and alterations either in the absolute [ATP], [ADP], [P(i)], and [PCr] or their ratios but did correlate with the levels of glycolytic intermediates. Higher [fructose-1,6-bisphosphate] and [glyceraldehyde-3-phosphate] and lower [glucose-6-phosphate] and [fructose-6-phosphate] accompanied faster glycolytic activity. Addition of rotenone markedly enhanced glycolysis at all pHe values studied. The increases were larger at higher [H+] so that the rate of lactate generation was only slightly lower at pH 6.2 than at 7.4 or 7.8. With rotenone present, [ATP] (and where relevant [PCr]) fell and [ADP] and [P(i)] rose under all pHe conditions. Simultaneously [glucose-6-phosphate] and [fructose-6-phosphate] decreased whereas [fructose-1,6-bisphosphate] and [glyceraldehyde-3-phosphate] increased; the levels of the last two were similar at pH 6.2 and 7.4.(ABSTRACT TRUNCATED AT 250 WORDS)
Erecińska
M
M
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104-6084, USA.
Deas
J
J
Silver
I A
IA
D000249:Adenosine Monophosphate / Q000378:metabolism; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004734:Energy Metabolism; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D007477:Ions; D009994:Osmolar Concentration; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D051381:Rats; D012402:Rotenone / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism*
D007477:Ions; D012402:Rotenone; D010758:Phosphorus; D000249:Adenosine Monophosphate; D000641:Ammonia; D010732:Phosphofructokinase-1