Biomaterial Database

A cholinergic chloride conductance in neurones of Helix aspersa. 1983

A S Finkel

Inhibitory Cl- -mediated currents through cholinergic channels on the soma of identified neurones from the right parietal ganglion of Helix aspersa were studied under voltage clamp. Voltage-jump relaxation analysis showed that these currents decreased with hyperpolarization. In 3 microM-acetylcholine (ACh), the normalized fraction of channels in the open configuration (rho) decreased e-fold with each 191 mV of membrane hyperpolarization. The steady-state membrane conductance, G(infinity), decreased e-fold with each 128 mV of membrane hyperpolarization. The difference in the voltage sensitivities of rho and G(infinity) arose because of the voltage sensitivity of the instantaneous membrane conductance, G(0). G(0) rectified in the direction predicted by the Goldman-Hodgkin-Katz conductance model. The degree of rectification decreased when the internal Cl- concentration was raised. The relaxing currents were composed of two exponential components. At membrane potential (Vm) = -160 mV, 12 degrees C, the time constants of the two components were 4.1 ms and 21 ms in 3 microM-ACh, and 3.6 ms and 18 ms in 100 microM-tetramethylammonium (TMA). Fluctuation analysis in neurones loaded with Cl- yielded spectra which were composed of two Lorentzian components. In 3 microM-ACh the mean single-channel conductance (gamma) appeared to rise from a low value observed in cells with normal intracellular Cl- to 2.7 pS in cells whose internal Cl- concentration was raised four-fold. The voltage sensitivity of rho was attributed to the conformational change step of a gating mechanism having three kinetically distinguishable states.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
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
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D006372	Helix, Snails	A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.	Helix (Snails),Snails Helix
D000109	Acetylcholine	A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.	2-(Acetyloxy)-N,N,N-trimethylethanaminium,Acetilcolina Cusi,Acetylcholine Bromide,Acetylcholine Chloride,Acetylcholine Fluoride,Acetylcholine Hydroxide,Acetylcholine Iodide,Acetylcholine L-Tartrate,Acetylcholine Perchlorate,Acetylcholine Picrate,Acetylcholine Picrate (1:1),Acetylcholine Sulfate (1:1),Bromoacetylcholine,Chloroacetylcholine,Miochol,Acetylcholine L Tartrate,Bromide, Acetylcholine,Cusi, Acetilcolina,Fluoride, Acetylcholine,Hydroxide, Acetylcholine,Iodide, Acetylcholine,L-Tartrate, Acetylcholine,Perchlorate, Acetylcholine
D000644	Quaternary Ammonium Compounds	Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN	Quaternary Ammonium Compound,Ammonium Compound, Quaternary,Ammonium Compounds, Quaternary,Compound, Quaternary Ammonium
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