Effect of fluoroacetate on the metabolism of isotopic acetate and lactate by the isolated perfused dog gastrocnemius

¹ Department of Physiology, University of Minnesota Medical School, Minneapolis, Minnesota

A study was made of the metabolism of C¹³-labeled acetate and lactate by the repetitively contracting (2/sec.), isolated, perfused dog gastrocnemius which had been poisoned by sodium fluoroacetate. When the fluoroacetate was administered at least 1/2 hour before the substrates, there followed a weakening of the contractions, a decrease in total CO₂ output, an enhanced disappearance of glycogen, an accumulation of lactic acid and a decrease in the pH of the blood. Under these conditions it was also found that the fluoroacetate greatly reduced the conversion to CO₂ of the carboxyl carbon of acetate and of the noncarboxyl carbons of lactate, but the carboxyl carbon of lactate still contributed a large fraction of the CO₂. These isotopic results are qualitatively consistent with predictions made from current concepts of intermediary metabolism and mode of action of fluoroacetate.

Note:
With the Technical Assistance of Joyce A. Swanson