Biomaterial Database

Regulation of the epithelial Na(+) channel by extracellular acidification. 2000

M S Awayda, and M J Boudreaux, and R L Reger, and L L Hamm

Departments of Medicine and of Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA. mawayda@tulane.edu

The effect of extracellular acidification was tested on the native epithelial Na(+) channel (ENaC) in A6 epithelia and on the cloned ENaC expressed in Xenopus oocytes. Channel activity was determined utilizing blocker-induced fluctuation analysis in A6 epithelia and dual electrode voltage clamp in oocytes. In A6 cells, a decrease of extracellular pH (pH(o)) from 7.4 to 6.4 caused a slow stimulation of the amiloride-sensitive short-circuit current (I(Na)) by 68.4 +/- 11% (n = 9) at 60 min. This increase of I(Na) was attributed to an increase of open channel and total channel (N(T)) densities. Similar changes were observed with pH(o) 5.4. The effects of pH(o) were blocked by buffering intracellular Ca(2+) with 5 microM 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. In oocytes, pH(o) 6.4 elicited a small transient increase of the slope conductance of the cloned ENaC (11.4 +/- 2.2% at 2 min) followed by a decrease to 83.7 +/- 11.7% of control at 60 min (n = 6). Thus small decreases of pH(o) stimulate the native ENaC by increasing N(T) but do not appreciably affect ENaC expressed in Xenopus oocytes. These effects are distinct from those observed with decreasing intracellular pH with permeant buffers that are known to inhibit ENaC.

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D002021	Buffers	A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.	Buffer
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D002614	Chelating Agents	Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.	Chelating Agent,Chelator,Complexons,Metal Antagonists,Chelators,Metal Chelating Agents,Agent, Chelating,Agents, Chelating,Agents, Metal Chelating,Antagonists, Metal,Chelating Agents, Metal
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D004232	Diuretics	Agents that promote the excretion of urine through their effects on kidney function.	Diuretic,Diuretic Effect,Diuretic Effects,Effect, Diuretic,Effects, Diuretic
D004533	Egtazic Acid	A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.	EGTA,Ethylene Glycol Tetraacetic Acid,EGATA,Egtazic Acid Disodium Salt,Egtazic Acid Potassium Salt,Egtazic Acid Sodium Salt,Ethylene Glycol Bis(2-aminoethyl ether)tetraacetic Acid,Ethylenebis(oxyethylenenitrile)tetraacetic Acid,GEDTA,Glycoletherdiamine-N,N,N',N'-tetraacetic Acid,Magnesium-EGTA,Tetrasodium EGTA,Acid, Egtazic,EGTA, Tetrasodium,Magnesium EGTA
D004847	Epithelial Cells	Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.	Adenomatous Epithelial Cells,Columnar Glandular Epithelial Cells,Cuboidal Glandular Epithelial Cells,Glandular Epithelial Cells,Squamous Cells,Squamous Epithelial Cells,Transitional Epithelial Cells,Adenomatous Epithelial Cell,Cell, Adenomatous Epithelial,Cell, Epithelial,Cell, Glandular Epithelial,Cell, Squamous,Cell, Squamous Epithelial,Cell, Transitional Epithelial,Cells, Adenomatous Epithelial,Cells, Epithelial,Cells, Glandular Epithelial,Cells, Squamous,Cells, Squamous Epithelial,Cells, Transitional Epithelial,Epithelial Cell,Epithelial Cell, Adenomatous,Epithelial Cell, Glandular,Epithelial Cell, Squamous,Epithelial Cell, Transitional,Epithelial Cells, Adenomatous,Epithelial Cells, Glandular,Epithelial Cells, Squamous,Epithelial Cells, Transitional,Glandular Epithelial Cell,Squamous Cell,Squamous Epithelial Cell,Transitional Epithelial Cell