Biomaterial Database

Chloride conductance in normal and myotonic muscle fibres and the action of monocarboxylic aromatic acids. 1971

S H Bryant, and A Morales-Aguilera

1. Cable parameters, component conductances, excitability and membrane potentials in isolated external intercostal fibre bundles at 38 degrees C from normal and myotonic goats were measured in normal and low-chloride Ringer, and in the presence of monocarboxylic aromatic acids that produce myotonic responses in mammalian muscle.2. The mean resting chloride conductance in mumho/cm(2) of myotonic fibres (range 0-147) was significantly less than that of normal fibres (range 376-951). The mean resting potassium conductance was higher in myotonic fibres (range 123-285) than in normal fibres (range 44-132). Potassium conductance increased about 10 mumho/cm(2) per mV increase in absolute resting potential.3. In normal fibres in normal Ringer 3-chloro-2,5,6-trimethylbenzoic acid; 5,6-dihydro-5,5-dimethyl-7-carboxybenz[c]acridine; phenanthrene-9-carboxylic acid; and anthracene-9-carboxylic acid at 10(-5)-10(-4)M decreased membrane conductance without consistently changing diameter or capacitance. In low-chloride Ringer 3-chloro-2,5,6-trimethylbenzoic acid (5 x 10(-5)M) increased potassium conductance in myotonic and normal fibres. It is concluded that these compounds block chloride conductance.4. The carboxylic acids produced myotonia in normal fibres similar to that in untreated myotonic fibres.5. Anthracene-9-carboxylic acid intravenously (8 mg/kg) in normal goats produced acutely a condition resembling myotonia congenita. The carboxylic acids produced no myotonic effects in frog muscle.

UI	MeSH Term	Description	Entries
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
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009222	Myotonia	Prolonged failure of muscle relaxation after contraction. This may occur after voluntary contractions, muscle percussion, or electrical stimulation of the muscle. Myotonia is a characteristic feature of MYOTONIC DISORDERS.	Myotonic Phenomenon,Percussion Myotonia,Myotonia, Percussion,Myotonias,Myotonias, Percussion,Myotonic Phenomenons,Percussion Myotonias,Phenomenon, Myotonic,Phenomenons, Myotonic
D010616	Phenanthrenes	POLYCYCLIC AROMATIC HYDROCARBONS composed of three fused BENZENE rings.
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011894	Rana pipiens	A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.	Frog, Leopard,Leopard Frog,Lithobates pipiens,Frogs, Leopard,Leopard Frogs
D002264	Carboxylic Acids	Organic compounds containing the carboxy group (-COOH). This group of compounds includes amino acids and fatty acids. Carboxylic acids can be saturated, unsaturated, or aromatic.	Carboxylic Acid,Acid, Carboxylic,Acids, Carboxylic
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
D006041	Goats	Any of numerous agile, hollow-horned RUMINANTS of the genus Capra, in the family Bovidae, closely related to the SHEEP.	Capra,Capras,Goat