Intestinal Synthesis of Riboflavin in the Rat

Abstract
The regression equation for the accumulation of riboflavin in the “system” for the riboflavin-deficient rat, as estimated from the variation of tissue, urine and fecal riboflavin less the riboflavin in the diet with time, showed that the rate of accumulation is 1.94 ± 0.28 µg per day per rat. This is approximately equal to the rate of fecal excretion of riboflavin. The fecal excretion of riboflavin is seen to be superimposed on a relatively constant riboflavin content of the tissues and of constant excretion of riboflavin in the urine. The rate of destruction of riboflavin was obtained from the slope of the regression equation for the variation of tissue C14-riboflavin with time, and observed to be -1.26 ± 0.21 µg per day per rat. The correction of the rate of accumulation of riboflavin in the “system” by use of the rate of destruction results in a value for the total rate of synthesis of riboflavin of 3.2 ± 0.21 µg per day in the riboflavin-deficient rat.