Balanced contribution of glycolytic and adenylate pool in supply of metabolic energy in platelets.

Abstract

When platelets are treated with H2O2 the metabolic ATP content decreases sharply (Holmsen, H., and Robkin, L. (1977) J. Biol. Chem. 252, 1752-1757). Here we report that the loss of metabolic energy is fully recovered in phosphorylated glycolytic intermediates. A mixture of antimycin A/2-deoxy-D-glucose/D-gluconic acid-1,5-lactone blocks mitochondrial ATP resynthesis and prevents the entry of sugars into the glycolytic sequence. The energy-rich phosphates in the adenylate and the glycolytic pool are then consumed in a specific order. First, the glycolytic pool is consumed at a rate of 4.5 mumol of ATP equivalents/min/10(11) cells, and metabolic ATP and ADP are kept stable; then the consumption of the glycolytic pool decreases and metabolic ATP and ADP are consumed, together keeping up with the same rate of energy consumption. Thrombin stimulation increases the energy consumption to about 17 mumol of ATPeq/min/10(11) cells which is now furnished by both the glycolytic and the adenylate pool, again with a preferential consumption of the former. The results show that H2O2 triggers a shift of energy-rich phosphates from the adenylate to the glycolytic pool and that the latter remains rapidly accessible to energy consumption thereby stabilizing the level of metabolic ATP. The adenylate energy charge is independent of the distribution of energy among the two pools, which extends its importance to the regulation of energy supply and demand beyond the adenylate pool.