Biomaterial Database

Sodium transport in salamander proximal tubule at 5.5 degrees C. 1991

N S Morgunov, and D J Hirsch

Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.

Na+ transport and electrophysiology of isolated perfused proximal tubules of the salamander Ambystoma tigrinum were compared at 22 and 5.5 degrees C, a range over which these animals normally live. Both intracellular Na+ activity and basolateral membrane potential were unaffected by temperature, whereas transepithelial potential depolarized from -6.5 +/- 0.8 mV at 22 degrees C to -3.5 +/- 0.6 mV at 5.5 degrees C (P less than 0.05). Compared with 22 degrees C, reduction of temperature to 5.5 degrees C included major increases in apical membrane resistance (2,052 +/- 473 omega.cm2 to 18,464 +/- 2,667 omega.cm2) and basolateral membrane resistance (491 +/- 113 omega.cm2 to 1,780 +/- 256 omega.cm2) (P less than 0.01). Sequential increases of luminal glucose concentration allowed characterization of the Na(+) -glucose cotransporter at both temperatures. The Km was stable (2 mM), but the maximal activity (Vmax) at 5.5 degrees C of 167 peq/5 cm2 increased to 1,000 peq/5 cm2 at 22 degrees C (P less than 0.05). In parallel with this temperature sensitivity of apical Na+ entry, basolateral Na+ pump activity was reduced at low temperature. Rubidium uptake at 22 degrees C was reduced by 40% at 5.5 degrees C. The rate of decrease of intracellular Na+ activity when tubules were perfused with substrate-free solution was -2.6 +/- 0.7 mM/min at 5.5 degrees C, compared with -4.9 +/- 1.2 mM/min at 22 degrees C. We conclude that low temperature reduces both Na+ uptake and efflux, allowing stability of intracellular milieu despite reduction in net transepithelial transport.

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
D009004	Monosaccharide Transport Proteins	A large group of membrane transport proteins that shuttle MONOSACCHARIDES across CELL MEMBRANES.	Hexose Transport Proteins,Band 4.5 Preactin,Erythrocyte Band 4.5 Protein,Glucose Transport-Inducing Protein,Hexose Transporter,4.5 Preactin, Band,Glucose Transport Inducing Protein,Preactin, Band 4.5,Proteins, Monosaccharide Transport,Transport Proteins, Hexose,Transport Proteins, Monosaccharide,Transport-Inducing Protein, Glucose
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
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
D000557	Ambystoma	A genus of the Ambystomatidae family. The best known species are the axolotl AMBYSTOMA MEXICANUM and the closely related tiger salamander Ambystoma tigrinum. They may retain gills and remain aquatic without developing all of the adult characteristics. However, under proper changes in the environment they metamorphose.	Amblystoma,Ambystoma tigrinum,Tiger Salamander,Amblystomas,Ambystomas,Salamander, Tiger,Salamanders, Tiger,Tiger Salamanders
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
D012413	Rubidium	An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.