title: On the uptake of biotin by the rat renal tubule.
abstract: Little is known of biotin handling by transporting epithelium. Accordingly, we have examined the characteristics of biotin uptake by rat renal tubular epithelium. Renal cortical slices showed concentrative, temperature-sensitive uptake of biotin. Renal brushborder membrane vesicles exhibited an "overshoot" phenomenon with uptake of 1.9 nM biotin in the presence of a 100 mM NaCl gradient. This overshoot was reduced in magnitude with reduction of the sodium gradient to 50 mM. Biocytin significantly reduced uptake by the vesicles. Concentration-dependent studies yielded an apparent transport Km of 200 nM. We conclude that biotin is actively transported by the rat renal proximal tubule by a system which is at least partially Na+ dependent, and shared by biocytin.
authors.affiliation: Department of Pediatrics, Medical College of Virginia, Richmond 23298.
authors.forename: P D
authors.initials: PD
authors.lastname: Spencer
authors.forename: K S
authors.initials: KS
authors.lastname: Roth
mesh_terms: D000818:Animals; D001710:Biotin / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D007684:Kidney Tubules / Q000378:metabolism*; D008297:Male; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001710:Biotin