The effect of vitamin B 6 on the in vivo utilization of radioactive phenylalanine

Abstract

The in vivo incorporation of phenylalanine-C 14 into tissues of control and vitamin B 6-deficient rats was investigated. Thirty minutes after the administration of the isotope, markedly higher levels of C 14 were found in the acid-soluble, lipide, and protein fractions of all control tissues examined as compared to those of vitamin B 6-deficient rats. Two hours and 7 hr. after the administration of phenylalanine-C 14, the acid-soluble fraction of all tissues from vitamin B 6-deficient animals exhibited higher levels of radioactivity than did similar tissues from control animals; however, the radiocarbon concentration in the lipides and proteins of control tissues remained higher. The administration of 1 mg. of pyridoxal daily for 3 days prior to the injection of phenylalanine-C 14 affected only slightly the uptake of C 14 in control animals; the levels of radioactivity in tissues from deficient animals similarly treated with pyridoxine tended to approximate control levels. The relation of these findings to amino acid transport into cells and to protein metabolism is discussed.