Biomaterial Database

Measuring intracellular ion concentrations with multi-barrelled microelectrodes. 2012

Anthony J Miller, and Susan Smith

Department of Disease and Stress Biology, John Innes Centre, Norwich, UK. tony.miller@jic.ac.uk

Ion-selective microelectrodes can be used to measure intracellular ion concentrations. The use of multi-barrelled electrodes enables the identification of the cellular compartment. For example, the inclusion of a pH-selective electrode enables the cytoplasm and vacuole to be distinguished. The ion-selective barrels of microelectrodes are filled with a sensor cocktail containing several different components. An ion-selective molecule, sensor or exchanger. Membrane solvent or plasticizer. Additives, e.g., lipophilic cation/anion. Membrane matrix to solidify the ion-selective membrane; essential for measurements in plant cells with a cell wall and turgor. For many ions, the ready-made membrane cocktail can be purchased, but the individual chemical components can be bought from suppliers and mixing the cocktail oneself is cheaper. For commercially available liquid membrane cocktails, the membrane matrix is not normally included. A matrix is needed if the microelectrodes are to be used in plants because cell turgor will displace a liquid membrane from the electrode tip, thereby changing or eliminating the sensitivity to the measuring ion. The matrix used is usually a high molecular weight poly(vinyl chloride), but can include other polymers, such as nitrocellulose for additional strength.

UI	MeSH Term	Description	Entries
D007477	Ions	An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
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
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
D009566	Nitrates	Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.	Nitrate
D003593	Cytoplasm	The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)	Protoplasm,Cytoplasms,Protoplasms
D012996	Solutions	The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)	Solution
D017360	Arabidopsis	A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.	Arabidopsis thaliana,Cress, Mouse-ear,A. thaliana,A. thalianas,Arabidopses,Arabidopsis thalianas,Cress, Mouse ear,Cresses, Mouse-ear,Mouse-ear Cress,Mouse-ear Cresses,thaliana, A.,thaliana, Arabidopsis,thalianas, A.
D017736	Ion-Selective Electrodes	Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions.	Electrodes, Ion-Selective,Ion Selective Electrode,Ion-Sensitive Electrode,Ion-Sensitive Electrodes,Electrode, Ion Selective,Electrode, Ion-Selective,Electrode, Ion-Sensitive,Electrodes, Ion Selective,Electrodes, Ion-Sensitive,Ion Selective Electrodes,Ion Sensitive Electrode,Ion Sensitive Electrodes,Ion-Selective Electrode,Selective Electrode, Ion,Selective Electrodes, Ion
D018515	Plant Leaves	Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)	Plant Leaf,Leaf, Plant,Leave, Plant,Leaves, Plant,Plant Leave