Abstract
The intestinal absorption of vitamin B_2 was studied by in situ mesenteric perfusion system. Free form riboflavin (FR), FMN and FAD (1 mg each) were injected into the ligated jejunum of rat which was infused Krebs Ringer bicarbonate solution from the superior mesenteric artery. Perfusate was recovered from the mesenteric vein and the recoveries of the total riboflavin during 120 min after the administration of these 3 types vitamin B_2 were 1.0,1.5 and 2.8%, respectively. Furthermore, riboflavin and its esters were detected in the perfusates from ^<14>C-FR and ^<14>C-FAD given rats. There was a considerable amount of labeled substance which was not vitamin B_2 derivatives in the radio-paperchromatogram of the perfusate of ^<14>C-FR dosed rats, and it is suggested that a portion of riboflavin is decomposed in the process of absorption.
