Pyridoxal-5'-phosphate and pyridoxal biokinetics in male Wistar rats fed graded levels of vitamin B-6.
Biokinetic parameters of plasma pyridoxal-5'-phosphate (PLP) and pyridoxal (PL) disposition were studied in male Wistar rats (age 8 mo) fed a purified diet containing less than 0.5, approximately 3 or approximately 6 mg pyridoxine.HCl/kg diet from weaning, with animals fed the 6 mg/kg diet serving as the control group. Basal plasma PLP concentration was lower in both the less than 0.5 and 3 mg/kg diet groups than in control animals (98 +/- 12, 314 +/- 40 and 514 +/- 56 nmol/L, respectively). Basal plasma PL concentration was lower in the less than 0.5 mg/kg diet group only [60 nmol/L (measured in pooled samples), 190 +/- 73 and 235 +/- 63 nmol/L for less than 0.5, 3 and 6 mg/kg diet groups, respectively]. In both the less than 0.5 and 3 mg/kg diet groups, PLP clearance was lower than in control rats (0.158 +/- 0.025, 0.131 +/- 0.040 and 0.240 +/- 0.051 L.h-1.kg body weight-1, respectively). In the less than 0.5 mg/kg diet group, PLP synthesis was more efficient than in control animals (34.7 +/- 9.3, 12.1 +/- 2.5 and 16.7 +/- 11.4% for less than 0.5, 3 and 6 mg/kg diet groups, respectively). In both the less than 0.5 and 3 mg/kg diet groups, volume of distribution of PLP as well as of PL was larger than in controls. It is concluded that B-6 vitamer metabolism is influenced by vitamin B-6 status. The metabolic pathway involved (PLP synthesis and/or PLP degradation) was observed to depend on degree of vitamin B-6 deficiency.
Bode
W
W
TNO-CIVO Toxicology and Nutrition Institute Zeist, Department of Clinical Biochemistry, The Netherlands.
van den Berg
H
H
D000818:Animals; D004435:Eating; D007275:Injections, Intravenous; D008297:Male; D011730:Pyridoxal / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011736:Pyridoxine / Q000008:administration & dosage* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D011730:Pyridoxal; D011732:Pyridoxal Phosphate; D011736:Pyridoxine