Biomaterial Database

Evidence for a Na+/K+/Cl- cotransport system in basolateral membrane vesicles from the rabbit parotid. 1986

R J Turner, and J N George, and B J Baum

Sodium (22Na) transport was studied in a basolateral membrane vesicle preparation from rabbit parotid. Sodium uptake was markedly dependent on the presence of both K+ and Cl- in the extravesicular medium, being reduced 5 times when K+ was replaced by a nonphysiologic cation and 10 times when Cl was replaced by a nonphysiologic anion. Sodium uptake was stimulated by gradients of either K+ or Cl (relative to nongradient conditions) and could be driven against a sodium concentration gradient by a KCl gradient. No effect of membrane potentials on KCl-dependent sodium flux could be detected, indicating that this is an electroneutral process. A KCl-dependent component of sodium flux could also be demonstrated under equilibrium exchange conditions, indicating a direct effect of K+ and Cl on the sodium transport pathway. KCl-dependent sodium uptake exhibited a hyperbolic dependence on sodium concentration consistent with the existence of a single-transport system with Km = 3.2 mM at 80 mM KCl and 23 degrees C. Furosemide inhibited this transporter with K0.5 = 2 X 10(4) M (23 degrees C). When sodium uptake was measured as a function of potassium and chloride concentrations a hyperbolic dependence on [K] (Hill coefficient = 0.87 +/- 0.09) and a sigmoidal dependence on [Cl] (Hill coefficient = 1.31 +/- 0.07) were observed, consistent with a Na/K/Cl stoichiometry of 1:1:2. Taken together these data provide strong evidence for the electroneutral coupling of sodium and KCl movements in this preparation and strongly support the hypothesis that a Na+/K+/Cl cotransport system thought to be associated with transepithelial chloride and water movements in many exocrine glands is present in the parotid acinar basolateral membrane.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D010306	Parotid Gland	The largest of the three pairs of SALIVARY GLANDS. They lie on the sides of the FACE immediately below and in front of the EAR.	Gland, Parotid,Glands, Parotid,Parotid Glands
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.
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
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
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