MICE, HAMSTERS AND GUINEA-PIGS DIFFER IN EFFICIENCY OF PYRIDOXINE-5'-BETA-D-GLUCOSIDE UTILIZATION

Mice, hamsters and guinea pigs were studied to assess species variatio n in utilization of pyridoxine-5'-D-glucoside (PN-glucoside), a form o f vitamin B-6 found in plants. Animals fed vitamin B-6-deficient or ma rginally supplemented diets [1 mg pyridoxine(PN)/kg] were given an ora l dose of [H-3]PN-glucoside plus [C-14]PN. Urinary and fecal isotopic excretion was measured over 24 h and the distribution of B-6 vitamers in liver determined at the end of the 24-h period. Intestinal absorpti on was nearly complete, as very little (<6%) of each isotope was excre ted in the feces. In mice, hamsters and guinea pigs, 31.3, 31.5 and 9. 5%, respectively, of urinary H-3 was present as intact PN-glucoside. I ncorporation into liver was reflected by H-3/C-14 ratios of hepatic vi tamin B-6 as follows: mice, 0.39; hamsters, 0.73; guinea pigs, 1.49 (m eans for both diets). The intake of dietary vitamin B-6 had little eff ect on [H-3]PN-glucoside metabolism. Guinea pigs displayed greater uti lization of PN-glucoside than did mice, hamsters or rats (seen previou sly), although they may not be the best animal model for the study of PN-glucoside metabolism. Because the bioavailability of PN-glucoside i n humans has been estimated to be 58% relative to PN, mice or hamsters , rather than guinea pigs or rats, would be better species for quantit ative studies of PN-glucoside bioavailability and associated enzymatic processes.