Biomaterial Database

Influence of extracellular and intracellular pH on GABA-gated chloride conductance in crayfish muscle fibres. 1992

M Pasternack, and C Bountra, and J Voipio, and K Kaila

Department of Zoology, University of Helsinki, Finland.

The effect of intracellular and extracellular pH on GABA-gated Cl- conductance was studied using H(+)-selective microelectrodes and a three-microelectrode voltage clamp in crayfish leg opener muscle fibres in bicarbonate-free solutions. Experimental variation of intracellular pH in the range 6.4-8.0 did not affect the GABA-gated conductance. In contrast to this, the GABA-gated conductance was sensitive to changes in external pH. Raising the external pH from 7.4 to 8.4 decreased the GABA-gated peak conductance observed immediately following application of GABA by 30%, and a change from 7.4 to 6.4 produced an increase of 26%. The effect of extracellular pH on the GABA-gated peak conductance was approximately linear in the pH range 6.4-8.9. A slight decrease in the slope of the pH-conductance relationship was evident in the pH range 5.4-6.4. The desensitization of the GABA-gated conductance was also affected by external pH. At pH 6.9 the conductance produced by 1 mM GABA showed a desensitization of about 15%, and at pH 8.9 this value was 34%. Raising the external pH in the presence of GABA decreased the GABA-gated peak conductance and increased the fractional desensitization, while lowering the external pH produced opposite effects, and was capable of repriming the conductance from a desensitized state to the non-desensitized state. The above results show that the GABA-gated conductance is sensitive to changes in external pH in the physiological range, and suggest that pH-dependent changes in the postsynaptic efficacy of GABA-mediated inhibition may contribute to H+ modulation of neuronal excitability.

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
D008565	Membrane Proteins	Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.	Cell Membrane Protein,Cell Membrane Proteins,Cell Surface Protein,Cell Surface Proteins,Integral Membrane Proteins,Membrane-Associated Protein,Surface Protein,Surface Proteins,Integral Membrane Protein,Membrane Protein,Membrane-Associated Proteins,Membrane Associated Protein,Membrane Associated Proteins,Membrane Protein, Cell,Membrane Protein, Integral,Membrane Proteins, Integral,Protein, Cell Membrane,Protein, Cell Surface,Protein, Integral Membrane,Protein, Membrane,Protein, Membrane-Associated,Protein, Surface,Proteins, Cell Membrane,Proteins, Cell Surface,Proteins, Integral Membrane,Proteins, Membrane,Proteins, Membrane-Associated,Proteins, Surface,Surface Protein, Cell
D009118	Muscimol	A neurotoxic isoxazole isolated from species of AMANITA. It is obtained by decarboxylation of IBOTENIC ACID. Muscimol is a potent agonist of GABA-A RECEPTORS and is used mainly as an experimental tool in animal and tissue studies.	Agarin,Pantherine
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D003400	Astacoidea	A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.	Astacus,Crayfish,Procambarus,Astacoideas,Crayfishs
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005680	gamma-Aminobutyric Acid	The most common inhibitory neurotransmitter in the central nervous system.	4-Aminobutyric Acid,GABA,4-Aminobutanoic Acid,Aminalon,Aminalone,Gammalon,Lithium GABA,gamma-Aminobutyric Acid, Calcium Salt (2:1),gamma-Aminobutyric Acid, Hydrochloride,gamma-Aminobutyric Acid, Monolithium Salt,gamma-Aminobutyric Acid, Monosodium Salt,gamma-Aminobutyric Acid, Zinc Salt (2:1),4 Aminobutanoic Acid,4 Aminobutyric Acid,Acid, Hydrochloride gamma-Aminobutyric,GABA, Lithium,Hydrochloride gamma-Aminobutyric Acid,gamma Aminobutyric Acid,gamma Aminobutyric Acid, Hydrochloride,gamma Aminobutyric Acid, Monolithium Salt,gamma Aminobutyric Acid, Monosodium Salt
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations