Biomaterial Database

Transepithelial transport in cell culture: stoichiometry of Na/phlorizin binding and Na/D-glucose cotransport. A two-step, two sodium model of binding and translocation. 1982

D S Misfeldt, and M J Sanders

The renal cell line LLC-PK1 cultured on a membrane filter forms a functional epithelial tissue. This homogeneous cell population exhibits rheogenic Na-dependent D-glucose coupled transport. The short-circuit current (Isc) was accounted for by net apical-to-basolateral D-glucose coupled Na flux, which was 0.53 +/- 0.09(8) mueq cm-2hr-1, and Isc, 0.50 +/- 0.50(8) mueq cm-2hr-1. A linear plot of concurrent net Na vs. net D-glucose apical-to-basolateral fluxes a gave a regression coefficient of 2.08. As support for a 2:1 transepithelial stoichiometry, sodium was added in the presence of D-glucose and the response of Isc analyzed by a Hill plot. A slope of 2.08 +/- 0.06(5) was obtained confirming a requirement of 2 Na for 1 D-glucose coupled transport. A Hill plot of Isc increase to added D-glucose in the presence of Na gave a slope of 1.02 +/- 0.02(5). A direct determination of the initial rates of Na and D-glucose translocation across the apical membrane using phlorizin, a nontransported glycoside competitive inhibitor to identify the specific coupled uptake, gave a stoichiometry of 2.2. A coupling ratio of 2 for Na, D-glucose uptake, doubles the potential energy available for Na-gradient coupled D-glucose transport. In contrast to coupled uptake, the stoichiometry for Na-dependent-phlorizin binding was 1.1 +/- 0.1(8) from Hill plot analyses of Na-dependent-phlorizin binding as a function of [Na].(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D010695	Phlorhizin		Phloridzin,Phlorizin
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004563	Electrochemistry	The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.	Electrochemistries
D004848	Epithelium	The layers of EPITHELIAL CELLS which cover the inner and outer surfaces of the cutaneous, mucus, and serous tissues and glands of the body.	Mesothelium,Epithelial Tissue,Mesothelial Tissue,Epithelial Tissues,Mesothelial Tissues,Tissue, Epithelial,Tissue, Mesothelial,Tissues, Epithelial,Tissues, Mesothelial
D005947	Glucose	A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.	Dextrose,Anhydrous Dextrose,D-Glucose,Glucose Monohydrate,Glucose, (DL)-Isomer,Glucose, (alpha-D)-Isomer,Glucose, (beta-D)-Isomer,D Glucose,Dextrose, Anhydrous,Monohydrate, Glucose
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
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23