Metabolism of [14C]- and [32P]Pyridoxal 5-Phosphate and [3H]pyridoxal Administered Intravenously to Pigs and Goats

Document Type


Publication Date


Publication Source

Journal of Nutrition





Inclusive pages



To gain more information about the kinetics of vitamin B-6 metabolism in vivo, the metabolism of tracer was examined after the simultaneous intravenous administration of [32P] and [14C]pyridoxal phosphate and [3H]pyridoxal in two 93-kg pigs and two 60-kg goats. In the pigs, [14C] removal was monophasic with T1/2 of 16 and 18 min and clearance of 165 and 248 mL/min. In the goats, [14C] removal was biphasic with T1/2 of 49 and 114 min for 0-30 min and 209 and 227 min for 0.5-6 h (clearance 20 and 17 mL/min). Uptake of pyridoxal phosphate by liver and resecretion into the plasma were too small to cause a detectable decrease in the [32P]:[14C] ratio. Pyridoxal removal from plasma was similar in both species, with a half-life of approximately 12 min from 0-30 min and approximately 50 min for 0.5-3 h. Clearance of [3H]pyridoxal in the four animals ranged from 412 to 2258 mL/min. Little [14C] entered the erythrocytes. The [3H] entered readily but was converted to pyridoxal phosphate faster in the pigs than in the goats. [14C] and [3H] were excreted as pyridoxic acid at the same rate. However, during the 54 h after injection the goats excreted approximately 60% of the [14C] doses in the urine compared with approximately 30% in the pigs. About 5-10% of the [14C] and [3H] doses were recovered in goat milk over 54 h. Pyridoxal kinase activity was higher in lactating mammary tissue than in liver, kidney or muscle of goats.



This document is currently not available here.

  Contact Author



Link to Original Published Item