Management of pyridoxine and pyridoxal in the isolated kidney of the rat
Hamm, M.W.; Mehansho, H.; Henderson, L.M.
Journal of Nutrition 110(8): 1597-1609
1980
ISSN/ISBN: 0022-3166 PMID: 7400849 Document Number: 164099
The vascularly perfused kidney of the rat was used to study the transport, metabolism, filtration, secretion, reabsorption and excretion of pyridoxine (PN) and pyridoxal (PL), independent of other tissues including erythrocytes. [3H]PN or [3H]PL was given via the perfusate at concentrations from 8 nmol to 20.75 mu mol/95 ml perfusate. After 30 min of perfusion with 8 nmol [3H]PN, 17.2% of the total 3H was found in the kidney. As the concentration of PN in the perfusate was increased the percentage in the kidney decreased. This inverse relation resulted primarily from saturation of PL kinase in the kidney. With all amounts about one-half as much 3H was found in the kidney after [3H]PL as after [3H]PN at the same concentration. With PN the primary metabolite in the kidney was PNP whereas with PL, significant amounts of PLP, PMP and pyridoxic acid were found. A differential response in the renal tubular handling of PN and PL was also found. With all amounts of PL, most of the vitamer filtered was reabsorbed. The same was true with the smallest amount although at higher concentrations there was a net secretion of PN into the urine via a saturable process; that could account for the ratio greater than 1 of kidney:perfusate concentration of PN.