Biomaterial Database

pH gradient-stimulated transport of urate and p-aminohippurate in dog renal microvillus membrane vesicles. 1980

J W Blomstedt, and P S Aronson

The transport mechanism of urate and p-aminohippurate (PAH) was evaluated in microvillus membrane vesicles isolated from the renal cortex of the mongrel dog. Imposition of a transmembrane pH gradient (pHo less than pH1) markedly accelerated the uptake of [14C]urate and [3H]PAH and caused the transient accumulation ("overshoot") of each anion above its final level of uptake. The transport of urate and PAH under both stimulated (pHo less than pHi) and basal (pHo = pHi) conditions was insensitive to valinomycin-induced K+ diffusion potentials. The pH gradient-stimulated uptake of 25 microM [14C]urate and 1.0 microM [3H]PAH was significantly inhibited by 1.2 mM PAH, urate, furosemide, salicylate, or probenecid. The effect of each inhibitor on [14C]urate transport was identical to the effect of the same inhibitor on [3H]PAH flux. We conclude that the transport of urate and PAH in dog renal microvillus membrane vesicles occurs via a pH gradient-stimulated electroneutral carrier-mediated process such as 1:1 H+-anion cotransport or OH-anion exchange. Such a transport mechanism may possibly play a role in effecting uphill urate reabsorption in the proximal tubule. Moreover, this study demonstrates that secondary active solute transport in epithelial membranes may be coupled to the electrochemical gradient of an ion other than Na+.

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
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
D009994	Osmolar Concentration	The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.	Ionic Strength,Osmolality,Osmolarity,Concentration, Osmolar,Concentrations, Osmolar,Ionic Strengths,Osmolalities,Osmolar Concentrations,Osmolarities,Strength, Ionic,Strengths, Ionic
D010130	p-Aminohippuric Acid	The glycine amide of 4-aminobenzoic acid. Its sodium salt is used as a diagnostic aid to measure effective renal plasma flow (ERPF) and excretory capacity.	4-Aminohippuric Acid,para-Aminohippuric Acid,Aminohippurate Sodium,Aminohippuric Acid,Nephrotest,Sodium Para-Aminohippurate,p-Aminohippurate,4 Aminohippuric Acid,Para-Aminohippurate, Sodium,Sodium Para Aminohippurate,Sodium, Aminohippurate,p Aminohippurate,p Aminohippuric Acid,para Aminohippuric Acid
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000618	Aminohippuric Acids	A group of glycine amides of aminobenzoic acids.	Acids, Aminohippuric
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