Glycine Metabolism in Vitamin B6-deficient and Deoxypyridoxine-treated Rats

Abstract

Further studies in support of previous work indicating that vitamin B6 deficiency and deoxypyridoxine alter the metabolism of glycine by rats have been conducted. Vitamin B6 deficiency resulted in significant elevation in the free glycine of rat liver, kidney, blood and muscle. This effect was not accentuated by deoxypyridoxine and was prevented in liver and kidney. When vitamin B6-deficient rats were injected with glycine-1-14C less 14CO2 was expired than by controls. Deoxypyridoxine neither reversed nor increased this effect. Rats receiving deoxyridoxine converted less labeled glycine, glyoxylate and glycolate to hippuric acid than vitamin B6-deficient rats not receiving the analogue. Liver and kidney homogenates from vitamin B6-deficient rats showed a decreased ability to oxidize glycine-1-14C to 14CO2. This did not occur in liver homogenates from rats fed deoxypyridoxine, although kidney homogenates from these rats acted similarly to those from vitamin B6-deficient animals not receiving deoxypyridoxine. The addition of pyridoxal-5-phosphate to liver homogenates increased glycine oxidation in the homogenates from control rats and from both experimental groups to levels which were not significantly different. In contrast, pyridoxal-5-phosphate did not alter the glycine oxidation of control kidney homogenates and did not raise the activity of kidney homogenates from the deficient groups to control levels.