Biomaterial Database

Noise analysis of drug induced voltage clamp currents in denervated frog muscle fibres. 1976

E Neher, and B Sakmann

1. Voltage clamp currents were recorded during iontophoretic application of steady doses of acetylcholine (ACh), carbachol or suberyldicholine to hyperpersensitive extrasynaptic regions of chronically denervated frog muscle fibers. Autocorrelation functions of drug induced current fluctuations were calculated and estimates of conductance gamma and average open time tau of the extrasynaptic ion channels were derived. 2. The average open time of an extrajunctional channel induced by acetylcholine is tauACh = 11 +/- 1-6 msec (+/- S.E.) at -80 mV and 8 degrees C. Carbachol and suberyldicholine open channels of tauCarb = 3-9 +/- 0-4 msec and tauSubCh = 19 +/- 2-5 msec (+/- S.E.) duration under the same conditions. The average open time of the extrasynaptic channel produced by each drug is three to five times longer than the value found for junctional channels in normal fibres. 3. The average open time of the extrajunctional channel is dependent on temperature and membrane potential. Lowering the temperature or increasing the membrane potential increases the average open time of the channels induced by any one of the drugs. 4. The conductance of a single extrajunctional channel opened by the action of acetylcholine is estimated to be gammaextra = 15 +/- 1-8 pmho (+/- S.E.). This is somewhat lower than the value of gammaep = 23 +/- 2 pmho (+/- S.E.) found for the conductance of a single open channel in the junctional membrane of normal fibres. The extrasynaptic channels opened by the action of carbachol and suberyldicholine have similar conductances to those produced by ACh. 5. The autocorrelation function of drug-induced current fluctuations, recorded at the former end-plate region of chronically denervated fibres often shows both a fast and a slow time constant. They correspond in value to the time constant of the autocorrelation function obtained from end-plate currents in normal fibres and from extrasynaptic currents in denervated fibres respectively. This could indicate that two populations of channels exist at the former end-plate region of denervated muscle fibres.

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
D009045	Motor Endplate	The specialized postsynaptic region of a muscle cell. The motor endplate is immediately across the synaptic cleft from the presynaptic axon terminal. Among its anatomical specializations are junctional folds which harbor a high density of cholinergic receptors.	Motor End-Plate,End-Plate, Motor,End-Plates, Motor,Endplate, Motor,Endplates, Motor,Motor End Plate,Motor End-Plates,Motor Endplates
D009121	Muscle Denervation	The resection or removal of the innervation of a muscle or muscle tissue.	Denervation, Muscle,Denervations, Muscle,Muscle Denervations
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D010277	Parasympathomimetics	Drugs that mimic the effects of parasympathetic nervous system activity. Included here are drugs that directly stimulate muscarinic receptors and drugs that potentiate cholinergic activity, usually by slowing the breakdown of acetylcholine (CHOLINESTERASE INHIBITORS). Drugs that stimulate both sympathetic and parasympathetic postganglionic neurons (GANGLIONIC STIMULANTS) are not included here.	Parasympathomimetic Agents,Parasympathomimetic Drugs,Parasympathomimetic Effect,Parasympathomimetic Effects,Agents, Parasympathomimetic,Drugs, Parasympathomimetic,Effect, Parasympathomimetic,Effects, Parasympathomimetic
D011893	Rana esculenta	An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".	Pelophylax esculentus
D011896	Rana temporaria	A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.	European Common Frog,Frog, Common European,Common European Frog,Common Frog, European,European Frog, Common,Frog, European Common
D002217	Carbachol	A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.	Carbamylcholine,Carbacholine,Carbamann,Carbamoylcholine,Carbastat,Carbocholine,Carboptic,Doryl,Isopto Carbachol,Jestryl,Miostat,Carbachol, Isopto
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
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