Biomaterial Database

Microelectrode studies in the frog isolated spinal cord during depression by general anaesthetic agents. 1969

A Richens

1. Extracellular and intracellular potentials have been recorded from the isolated spinal cord of the frog during depression of synaptic transmission by volatile and barbiturate general anaesthetic agents.2. Volatile agents did not impair conduction in presynaptic terminals in concentrations which completely blocked synaptic transmission.3. Methohexitone consistently impaired conduction in presynaptic terminals long before transmission through polysynaptic pathways was blocked.4. Volatile agents depressed the excitability of the motoneurone membrane, as evidenced by impaired antidromic invasion, reduced excitability to direct stimulation, depression of the synaptic potential and elevation of firing threshold. It is concluded that these actions are responsible for the depressant effect of volatile agents on spinal reflexes.5. Methohexitone produced an increase in the excitability of the motoneurone membrane, as evidenced by enhanced antidromic invasion, increased excitability to direct stimulation and potentiation of short latency responses. Despite this excitatory action, the polysynaptic pathways through the cord were depressed by an action of the drug on conduction in presynaptic terminals.6. It is suggested that the sensitivity of the motoneurone membrane to volatile agents may contribute to the good muscle relaxant properties of these drugs in clinical use.

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
D008723	Methohexital	An intravenous anesthetic with a short duration of action that may be used for induction of anesthesia.	Methohexitone,Brevimytal Natrium,Brevital,Brietal,Brietal-Sodium,Methohexital Sodium,Methohexital, Monosodium Salt,Brietal Sodium,Monosodium Salt Methohexital,Natrium, Brevimytal,Sodium, Methohexital
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D002725	Chloroform	A commonly used laboratory solvent. It was previously used as an anesthetic, but was banned from use in the U.S. due to its suspected carcinogenicity.	Trichloromethane
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D005018	Ethyl Chloride	A gas that condenses under slight pressure. Because of its low boiling point ethyl chloride sprayed on skin produces an intense cold by evaporation. Cold blocks nerve conduction. Ethyl chloride has been used in surgery but is primarily used to relieve local pain in sports medicine.	Chloroethane,Chloraethyl Dr. Henning,Cloretilo Chemirosa,Gebauer's Ethyl Chloride,WariActiv,Chemirosa, Cloretilo,Chloride, Ethyl,Gebauer Ethyl Chloride,Gebauers Ethyl Chloride
D006221	Halothane	A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)	1,1,1-Trifluoro-2-Chloro-2-Bromoethane,Fluothane,Ftorotan,Narcotan
D000777	Anesthetics	Agents capable of inducing a total or partial loss of sensation, especially tactile sensation and pain. They may act to induce general ANESTHESIA, in which an unconscious state is achieved, or may act locally to induce numbness or lack of sensation at a targeted site.	Anesthetic,Anesthetic Agents,Anesthetic Drugs,Anesthetic Effect,Anesthetic Effects,Agents, Anesthetic,Drugs, Anesthetic,Effect, Anesthetic,Effects, Anesthetic
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
D001001	Anura	An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.	Bombina,Frogs and Toads,Salientia,Toad, Fire-Bellied,Toads and Frogs,Anuras,Fire-Bellied Toad,Fire-Bellied Toads,Salientias,Toad, Fire Bellied,Toads, Fire-Bellied