Biomaterial Database

Tracer Na fluxes in Necturus proximal tubule. 1977

K R Spring, and G Giebisch

Steady-state bidirectional sodium fluxes were measured across Necturus proximal tubules. New methods for capillary perfusion and collection of venous effluent enabled flux determination to be made from the appearance of luminal tracer in the capillaries. Fluxes and permeability were measured in the absence of net fluid reabsorption. The sodium permeability measured in the plasma-to-lumen direction was 3 X 10(-6) cm/s. The flux ratio (lumen-to-plasma/plasma-to-lumen) was about twice the passive value calculated from the measured concentrations and potentials. Estimates for the permeability and flux across the shunt pathway were obtained from nonsteady-state flux determinations. The shunt pathway appeared to be the most significant route for passive sodium movement from plasma-to-lumen. Nonsteady-state tracer measurements also enabled an estimate to be made of the lumenal cell membrane permeability and unidirectional sodium flux. Two-thirds of the lumen-to-plasma flux was calculated to traverse the cellular path and the remainder through the shunt. Approximately one-third of the intracellular sodium was found to exchange rapidly with tracer.

UI	MeSH Term	Description	Entries
D007687	Kidney Tubules, Proximal	The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE.	Proximal Kidney Tubule,Proximal Renal Tubule,Kidney Tubule, Proximal,Proximal Kidney Tubules,Proximal Renal Tubules,Renal Tubule, Proximal,Renal Tubules, Proximal,Tubule, Proximal Kidney,Tubule, Proximal Renal,Tubules, Proximal Kidney,Tubules, Proximal Renal
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D005110	Extracellular Space	Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.	Intercellular Space,Extracellular Spaces,Intercellular Spaces,Space, Extracellular,Space, Intercellular,Spaces, Extracellular,Spaces, Intercellular
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
D014562	Urodela	An order of the Amphibia class which includes salamanders and newts. They are characterized by usually having slim bodies and tails, four limbs of about equal size (except in Sirenidae), and a reduction in skull bones.	Amphiuma,Caudata,Eel, Congo,Salamanders,Congo Eel,Congo Eels,Eels, Congo,Salamander