Metabolism of [14C]- and [32P]pyridoxal 5'-phosphate and [3H]pyridoxal administered intravenously to pigs and goats.
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.
Coburn
S P
SP
Biochemistry Department, Fort Wayne State Developmental Center, IN 46835.
Mahuren
J D
JD
Kennedy
M S
MS
Schaltenbrand
W E
WE
Townsend
D W
DW
D000818:Animals; D005260:Female; D006041:Goats; D006207:Half-Life; D007275:Injections, Intravenous; D007668:Kidney / Q000201:enzymology; D007774:Lactation / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008321:Mammary Glands, Animal / Q000201:enzymology; D009132:Muscles / Q000201:enzymology; D010084:Oxidation-Reduction; D011730:Pyridoxal / Q000493:pharmacokinetics*; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000493:pharmacokinetics*; D013552:Swine; D014018:Tissue Distribution
D011730:Pyridoxal; D011732:Pyridoxal Phosphate