title: Agmatine transport in brain mitochondria: a different mechanism from that in liver mitochondria.
abstract: The diamine agmatine (AGM), exhibiting two positive charges at physiological pH, is transported into rat brain mitochondria (RBM) by an electrophoretic mechanism, requiring high membrane potential values and exhibiting a marked non-ohmic force-flux relationship. The mechanism of this transport apparently resembles that observed in rat liver mitochondria (RLM), but there are several characteristics that strongly suggest the presence of a different transporter of agmatine in RBM. In this type of mitochondria, the extent of initial binding and total accumulation is higher and lower, respectively, than that in liver; saturation kinetics and the flux-voltage relationship also exhibit different trends, whereas idazoxan and putrescine, ineffective in RLM, act as inhibitors. The characteristics of agmatine uptake in RBM lead to the conclusion that its transporter is a channel with two asymmetric energy barriers, showing some characteristics similar to those of the imidazoline receptor I(2) and the sharing with the polyamine transporter.
authors.affiliation: Department of Biological Chemistry, University of Padova, Viale G. Colombo, 3, 35121, Padova, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Battaglia
authors.forename: S
authors.initials: S
authors.lastname: Grancara
authors.forename: M
authors.initials: M
authors.lastname: Mancon
authors.forename: C
authors.initials: C
authors.lastname: Cravanzola
authors.forename: S
authors.initials: S
authors.lastname: Colombatto
authors.forename: M A
authors.initials: MA
authors.lastname: Grillo
authors.forename: G
authors.initials: G
authors.lastname: Tempera
authors.forename: E
authors.initials: E
authors.lastname: Agostinelli
authors.forename: A
authors.initials: A
authors.lastname: Toninello
mesh_terms: D000376:Agmatine / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000378:metabolism*; D007700:Kinetics; D008930:Mitochondria, Liver / Q000737:chemistry / Q000378:metabolism*; D051381:Rats
chemical_list: D000376:Agmatine