title: Thiamin uptake by rat isolated enterocytes: relationship between transport and phosphorylation.
abstract: The membrane and intracellular steps of thiamin (T) uptake were studied in rat isolated enterocytes. The membrane step was investigated by using enterocytes deenergized with 25 microM rotenone and a short (30 s) incubation time, while the intracellular metabolic step was assessed by using normoenergized (normal) cells incubated for a longer (30 min) time. Evaluation of Km, Jmax and KD (apparent passive permeability coefficient) values, at 30 s incubation, indicated that deenergization slightly reduced both the affinity and the capacity of the saturable component of T uptake, as well as the capacity of the non-saturable component. At 30 min incubation, deenergization suppressed completely the saturable component, without affecting the non-saturable component. Comparison of the Km and Jmax values of the saturable components in normoenergized enterocytes at 30 s and 30 min indicated that intracellular metabolic phosphorylation is probably the event responsible for the active process involved in T uptake.
authors.affiliation: Istituto di Fisiologia umana, Università di Pavia, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Ricci
authors.forename: G
authors.initials: G
authors.lastname: Rindi
mesh_terms: D000818:Animals; D001692:Biological Transport; D004734:Energy Metabolism / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D012402:Rotenone / Q000494:pharmacology; D013831:Thiamine / Q000378:metabolism*
chemical_list: D012402:Rotenone; D013831:Thiamine