Biomaterial Database

Characterization of organic cation transport by avian renal brush-border membrane vesicles. 1995

A R Villalobos, and E J Braun

Department of Physiology, College of Medicine, University of Arizona, Tucson 85724, USA.

Organic cations are actively secreted by the renal proximal tubule. Studies on perfused tubules and isolated membranes from mammals and reptiles have demonstrated that organic cations (OC) are transported across the luminal (brush-border) membrane by OC/H+ exchange. Our objective was to determine whether a similar mechanism was present in the avian kidney. Uptake of [14C]tetraethylammonium (TEA) was assayed under various ionic conditions by rapid filtration in brush-border membrane vesicles (BBMV) isolated from chicken kidney (Gallus domesticus). An outwardly directed proton gradient (pHin = 6.0: pHout = 7.5) stimulated concentrative TEA uptake. TEA/H+ exchange was saturable, having a maximal rate of uptake of approximately 25 nmol.mg protein-1.min-1 and a Michaelis constant for TEA of approximately 500 microM. TEA transport could be indirectly coupled to sodium transport. Unlabeled TEA, N'-methylnicotinamide (NMN), choline, cimetidine, mepiperphenidol, quinidine, quinine, and ranitidine markedly cis-inhibited uptake of [14C]TEA. However, the organic anions probenecid and p-aminohippurate poorly inhibited uptake. Unlabeled TEA and NMN also trans-stimulated [14C]TEA uptake. Thus, in avian renal BBMV, organic cations are transported by an OC/H+ exchange mechanism qualitatively similar to that present in mammals.

UI	MeSH Term	Description	Entries
D007474	Ion Exchange	Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.	Exchange, Ion
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D008757	Methylglucosides		Methylglucopyranosides
D008871	Microvilli	Minute projections of cell membranes which greatly increase the surface area of the cell.	Brush Border,Striated Border,Border, Brush,Border, Striated,Borders, Brush,Borders, Striated,Brush Borders,Microvillus,Striated Borders
D011522	Protons	Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.	Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D002412	Cations	Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.	Cation
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D006859	Hydrogen	The first chemical element in the periodic table with atomic symbol H, and atomic number 1. Protium (atomic weight 1) is by far the most common hydrogen isotope. Hydrogen also exists as the stable isotope DEUTERIUM (atomic weight 2) and the radioactive isotope TRITIUM (atomic weight 3). Hydrogen forms into a diatomic molecule at room temperature and appears as a highly flammable colorless and odorless gas.	Protium,Hydrogen-1
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic