Effect of exogenous fructose-1,6-bisphosphate on glycolysis in the isolated perfused rat heart.

To test the mechanism of action of fructose-1,6-bisphosphate (F-1,6-P2), experiments were conducted on isolated perfused rat hearts to measure the glycolytic rate supported by exogenous glucose with simultaneous measurement of oxygen consumption and the release of lactate and pyruvate. Glycolysis was assayed in terms of the release of tritiated water from [5-3H] glucose, a measure of the rate through the aldolase step. It was found that 5 mmol/L F-1,6-P2 reduced the glycolytic rate parallel to the decrease in oxygen consumption. The results suggest that the cardioprotective action of F-1,6-P2 is related to a substrate effect and a decrease in adenosine triphosphate consumption as indicated by a decrease in oxygen consumption in accordance with the recent demonstration of Ca2+ binding by F-1,6-P2.