title: Uptake of pyridoxine hydrochloride by the rat jejunal mucosa in vitro.
abstract: The kinetics of mucosal membrane transport of pyridoxine hydrochloride were evaluated in vitro in the rat jejunum. Utilizing everted sacs and a double-label isotope technique, short-term incubation within the period of initial linear tissue uptake indicated: 1) no evidence of saturation of uptake over a wide pyridoxine-HCl concentration range (0.01 muM-10 mM); 2) failure of 4-deoxypyridoxine (10 muM), anoxia, iodoacetamide (5 mM), Na+ replacement and ouabain (1 mM) to inhibit uptake of 2 muM pyridoxine-HCl significantly; and 3) a low Q10 value of 1.31. Using single-label techniques, sacs were also incubated for 1 hour in 2 muM pyridoxine HCl with determination of the apparent tissue water-mucosal fluid concentration ratio and chromatographic separation of the various forms of vitamin B6 in tissue. Results demonstrated a failure of pyridoxine in tissue water to achieve a concentration in excess of that in the incubation medium. Data, therefore, were most consistent with passive diffusion as the mechanism for in vitro jejunal mucosal uptake of pyridoxine-HCl in the rat.
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D000860:Hypoxia / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism*; D007460:Iodoacetamide / Q000494:pharmacology; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011736:Pyridoxine / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology
chemical_list: D010042:Ouabain; D012964:Sodium; D011736:Pyridoxine; D007460:Iodoacetamide