Biomaterial Database

Changes in the conductance of the neuronal nicotinic acetylcholine receptor channel induced by magnesium. 1990

R Neuhaus, and A B Cachelin

Department of Pharmacology, University of Berne, Switzerland.

We have investigated the effect of magnesium on the single-channel conductance of neuronal nicotinic acetylcholine receptors (nAChRs) in nerve growth-factor treated rat pheochromocytoma (PC12) cells. The patch-clamp technique was used to record single-channel currents from cell attached and excised, outside-out patches in the presence of various internal and external Mg2+ concentrations. Mg2+ reduced the single-channel conductance in a concentration-dependent manner with an IC50 of 9.2 mM for external Mg2+ (inward conductance) and 0.69 mM for external Mg2+ (outward conductance). Both estimated and measured conductances for divalent cation-free CsCl solutions were around 60 pS. We also find that divalent cations are not involved in the inward rectification of whole-cell ACh-induced currents in these cells. Our results imply that the amino acids screened by divalent cations sense electric fields only weakly and are presumably outside the lipid bilayer. They also suggest that the density and the number of charges (or both) differ on either side of the ion pore.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
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
D009414	Nerve Growth Factors	Factors which enhance the growth potentialities of sensory and sympathetic nerve cells.	Neurite Outgrowth Factor,Neurite Outgrowth Factors,Neuronal Growth-Associated Protein,Neuronotrophic Factor,Neurotrophic Factor,Neurotrophic Factors,Neurotrophin,Neurotrophins,Growth-Associated Proteins, Neuronal,Neuronal Growth-Associated Proteins,Neuronotrophic Factors,Neurotrophic Protein,Neurotrophic Proteins,Proteins, Neuronal Growth-Associated,Factor, Neurite Outgrowth,Factor, Neuronotrophic,Factor, Neurotrophic,Factors, Nerve Growth,Factors, Neurite Outgrowth,Factors, Neuronotrophic,Factors, Neurotrophic,Growth Associated Proteins, Neuronal,Growth-Associated Protein, Neuronal,Neuronal Growth Associated Protein,Neuronal Growth Associated Proteins,Outgrowth Factor, Neurite,Outgrowth Factors, Neurite,Protein, Neuronal Growth-Associated
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D010673	Pheochromocytoma	A usually benign, well-encapsulated, lobular, vascular tumor of chromaffin tissue of the ADRENAL MEDULLA or sympathetic paraganglia. The cardinal symptom, reflecting the increased secretion of EPINEPHRINE and NOREPINEPHRINE, is HYPERTENSION, which may be persistent or intermittent. During severe attacks, there may be HEADACHE; SWEATING, palpitation, apprehension, TREMOR; PALLOR or FLUSHING of the face, NAUSEA and VOMITING, pain in the CHEST and ABDOMEN, and paresthesias of the extremities. The incidence of malignancy is as low as 5% but the pathologic distinction between benign and malignant pheochromocytomas is not clear. (Dorland, 27th ed; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p1298)	Pheochromocytoma, Extra-Adrenal,Extra-Adrenal Pheochromocytoma,Extra-Adrenal Pheochromocytomas,Pheochromocytoma, Extra Adrenal,Pheochromocytomas,Pheochromocytomas, Extra-Adrenal
D011978	Receptors, Nicotinic	One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for NICOTINE over MUSCARINE. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, and subunit composition of the receptors.	Nicotinic Acetylcholine Receptors,Nicotinic Receptors,Nicotinic Acetylcholine Receptor,Nicotinic Receptor,Acetylcholine Receptor, Nicotinic,Acetylcholine Receptors, Nicotinic,Receptor, Nicotinic,Receptor, Nicotinic Acetylcholine,Receptors, Nicotinic Acetylcholine
D002586	Cesium	A member of the alkali metals. It has an atomic symbol Cs, atomic number 55, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.	Caesium,Caesium-133,Cesium-133,Caesium 133,Cesium 133
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
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