It has been generally accepted that a concentration of 1 per cent sodium fluoride is adequate to prevent glycolysis in nonprecipitated blood and that no appreciable glycolysis results if the blood proteins are precipitated within 5 minutes after the blood is drawn (1). Determinations of lactic acid in the blood precipitated within 5 minutes or preserved in 1 per cent sodium fluoride have yielded a range of 8 to 20 mg. per cent for normal subjects under basal conditions.
We have had occasion to analyze pyruvic acid and lactic acid on the same blood samples. The analysis of pyruvic acid requires the use of iodoacetate as a stabilizing agent (2). The lactic acid values we observed in blood from normal fasting subjects at rest were found to be appreciably lower than those hitherto reported. We therefore reinvestigated the inhibitory effect of sodium fluoride and iodoacetate on glycolysis in human blood…
1. The rate of glycolysis in human blood was estimated from the changes in glucose and lactic acid. Either iodoacetate or sodium fluoride alone did not stop glycolysis completely. Complete inhibition of glycolysis was observed with a mixture of 1 per cent sodium fluoride and 1 per cent iodoacetate.
2. When suitable precautions were used, it was found that the normal lactic acid values in human blood ranged from 5 to 10 mg. per cent.
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