Abstract
2,3-Bisphosphoglycerate (2,3-BPG), a product of glycolysis via Embden-Meyerhof pathway, regulates the affinity of hemoglobin to oxygen. Strenuous exercise is known to affect the level of erythrocyte 2,3-BPG. We examined the effect of short time exercise on upper glycolytic intermediates in erythrocytes. Three normal men performed ergometer exercise at 200-300 watt for 2-3 minutes and then rested. Exercise caused a 9-fold increase in the levels of both fructose 1,6-bisphosphate (FBP), and dihydroxyacetone phosphate + glyceraldehyde 3-phosphate (DHAP + GAP) after 30 minutes.2,3 - BPG was not increased significantly. Since the concentration of 2,3- BPG is several magnitude more than that of FBP or DHAP + GAP, greater exercise load might be necessary for the increase in 2,3-BPG. Exercise also increased the blood lactate and pyruvate levels, and decreased blood pH by 0.15. Alteration of serum inorganic phosphate levels or oxygen saturation of hemoglobin failed to explain the observed alteration of erythrocyte glycolysis. We speculated that muscular adenine nucleotide degradation was accelerated during strenuous exercise because we observed elevations of blood hypoxanthine (20-fold), inosine (4-fold)and ammonia. Inosine is readily metabolized in erythrocytes and increases in FBP and DHAP+ GAP. We co nclude that exercise increases the upper glycolytic intermediates in erythrocytes through increased utilization of inosine, which is released from working muscle.
