Biomaterial Database

Inhibition of endothelium-derived relaxing factor in A6 cells. 1995

I Mountian, and M Granitzer

Laboratory for Physiology, KULeuven, Belgium.

The effects of endothelium-derived relaxing factor (EDRF) on Na+ transport in distal renal tubular A6 cells have been studied by inhibition of its synthesis with L-NAME (10(-2) mol/l). Na+ transport was monitored by measuring short-circuit current, cell voltage, transepithelial, apical and basolateral membrane conductances. EDRF production in A6 cells was tested by application of its substrate L-arginine. The blockade of EDRF decreased significantly the Na+ current (11 %), membrane potential (5 mV) and basolateral conductance (33 %), but did not affect the apical membrane conductance. Activation of apical Na+ conductance by dexamethasone incubation (10(-7) mol/l) did not further influence the drop in Na+ current. The involvement of basolateral K+ channels in cell depolarization and in the reduction of basolateral conductance was tested in tissues with elevated basolateral K+/Cl- conductance ratios (by increasing bath osmolarity) and by application of barium (0.5-10(-3) mol/l) a K+ channel blocker. The results showed that the effect of L-NAME on the short-circuit current was more pronounced in A6 cells with increased K+/Cl- conductance ratios, but was almost nullified by barium. Finally, L-arginine fully restored the Na+ current, thus reversing the inhibition induced by L-NAME. We conclude that EDRF is basally released in A6 cells. Inhibition of EDRF by L-NAME directly interferes with Na+ reabsorption. Since apical membrane conductance remains unchanged, the decrease in short-circuit current results from cell depolarization. The latter, together with the drop in basolateral conductance, might reflect inactivation of K+ channels.

UI	MeSH Term	Description	Entries
D007686	Kidney Tubules, Distal	The portion of renal tubule that begins from the enlarged segment of the ascending limb of the LOOP OF HENLE. It reenters the KIDNEY CORTEX and forms the convoluted segments of the distal tubule.	Distal Kidney Tubule,Distal Renal Tubule,Distal Kidney Tubules,Distal Renal Tubules,Kidney Tubule, Distal,Renal Tubule, Distal,Renal Tubules, Distal,Tubule, Distal Kidney,Tubule, Distal Renal,Tubules, Distal Kidney,Tubules, Distal Renal
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
D009569	Nitric Oxide	A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.	Endogenous Nitrate Vasodilator,Mononitrogen Monoxide,Nitric Oxide, Endothelium-Derived,Nitrogen Monoxide,Endothelium-Derived Nitric Oxide,Monoxide, Mononitrogen,Monoxide, Nitrogen,Nitrate Vasodilator, Endogenous,Nitric Oxide, Endothelium Derived,Oxide, Nitric,Vasodilator, Endogenous Nitrate
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
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
D001120	Arginine	An essential amino acid that is physiologically active in the L-form.	Arginine Hydrochloride,Arginine, L-Isomer,DL-Arginine Acetate, Monohydrate,L-Arginine,Arginine, L Isomer,DL Arginine Acetate, Monohydrate,Hydrochloride, Arginine,L Arginine,L-Isomer Arginine,Monohydrate DL-Arginine Acetate
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
D014982	Xenopus laevis	The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.	Platanna,X. laevis,Platannas,X. laevi