Cancellation of Fluoride Inhibition of Blood Glucose Catabolism *†

The soluble inorganic salts of fluoride are recognized to be highly toxic when administered parenterally or per os to animals or humans.15' 18,20 When taken in sufficiently large amounts such compounds may prove fatal within a matter of minutes. The fluoride ion appears to be an enzyme poison. 9'22' 34 It is known, for example, that fluoride added to suitable preparations of tissues or plants in vitro will block the enzyme enolase, forming a magnesium-fluoride-phosphate-enolase complex and thereby inhibiting glycolysis at the point where phosphoglyceric acid is converted to phosphopyruvic acid.0' 11, 35 Soluble inorganic salts of fluoride will also suppress the disappearance of glucose which characteristically occurs in blood on standing, but no data are available as to whether or not this effect is reversible.3' 4, 9, 17, 30, 32 Such information might well be useful in planning the therapy of fluoride poisoning. The studies herein reported, and presented in preliminary form elsewhere,5 indicate that in defibrinated blood this fluoride effect can in fact be cancelled by the introduction of certain calcium and magnesium salts.