Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.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.Simplexvirus: A genus of the family HERPESVIRIDAE, subfamily ALPHAHERPESVIRINAE, consisting of herpes simplex-like viruses. The type species is HERPESVIRUS 1, HUMAN.Patch-Clamp Techniques: An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.Tetrodotoxin: An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Sodium Channels: Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Ventricular Function: The hemodynamic and electrophysiological action of the HEART VENTRICLES.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.Potassium Channels: Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Heart: The hollow, muscular organ that maintains the circulation of the blood.Kunzea: A plant genus of the family MYRTACEAE. The common name of tea tree more often refers to MELALEUCA or LEPTOSPERMUM.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Neuroendoscopy: PROCEDURES that use NEUROENDOSCOPES for disease diagnosis and treatment. Neuroendoscopy, generally an integration of the neuroendoscope with a computer-assisted NEURONAVIGATION system, provides guidance in NEUROSURGICAL PROCEDURES.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.4-Aminopyridine: One of the POTASSIUM CHANNEL BLOCKERS, with secondary effect on calcium currents, which is used mainly as a research tool and to characterize channel subtypes.Synaptic Transmission: The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.Microelectrodes: Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)Pyramidal Cells: Projection neurons in the CEREBRAL CORTEX and the HIPPOCAMPUS. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region.Heart Ventricles: The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.Dendrites: Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Synapses: Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.Potassium Channel Blockers: A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.Tetraethylammonium CompoundsRefractory Period, Electrophysiological: The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.Potassium Channels, Voltage-Gated: Potassium channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. The opening of these channels is induced by the membrane depolarization of the ACTION POTENTIAL.Anti-Arrhythmia Agents: Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.Myocytes, Cardiac: Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).Models, Cardiovascular: Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.Arrhythmias, Cardiac: Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.Sodium Channel Blockers: A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.Deoxyadenosines: Adenosine molecules which can be substituted in any position, but are lacking one hydroxyl group in the ribose part of the molecule.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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.Delayed Rectifier Potassium Channels: A group of slow opening and closing voltage-gated potassium channels. Because of their delayed activation kinetics they play an important role in controlling ACTION POTENTIAL duration.Tetraethylammonium: A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)Oncogene Proteins v-fos: Transforming proteins coded by fos oncogenes. These proteins have been found in the Finkel-Biskis-Jinkins (FBJ-MSV) and Finkel-Biskis-Reilly (FBR-MSV) murine sarcoma viruses which induce osteogenic sarcomas in mice. The FBJ-MSV v-fos gene encodes a p55-kDa protein and the FBR-MSV v-fos gene encodes a p75-kDa fusion protein.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Evoked Potentials: Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Calcium Channels, L-Type: Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and nonexcitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Nurses: Professionals qualified by graduation from an accredited school of nursing and by passage of a national licensing examination to practice nursing. They provide services to patients requiring assistance in recovering or maintaining their physical or mental health.Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Myocardial Reperfusion: Generally, restoration of blood supply to heart tissue which is ischemic due to decrease in normal blood supply. The decrease may result from any source including atherosclerotic obstruction, narrowing of the artery, or surgical clamping. Reperfusion can be induced to treat ischemia. Methods include chemical dissolution of an occluding thrombus, administration of vasodilator drugs, angioplasty, catheterization, and artery bypass graft surgery. However, it is thought that reperfusion can itself further damage the ischemic tissue, causing MYOCARDIAL REPERFUSION INJURY.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Motor Neurons: Neurons which activate MUSCLE CELLS.Sinoatrial Node: The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).Autoreceptors: Transmitter receptors on or near presynaptic terminals (or varicosities) which are sensitive to the transmitter(s) released by the terminal itself. Receptors for the hormones released by hormone-releasing cells are also included.Voltage-Sensitive Dye Imaging: Optical imaging techniques used for recording patterns of electrical activity in tissues by monitoring transmembrane potentials via FLUORESCENCE imaging with voltage-sensitive fluorescent dyes.Endocardium: The innermost layer of the heart, comprised of endothelial cells.Calcium Signaling: Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Electrophysiological Phenomena: The electrical properties, characteristics of living organisms, and the processes of organisms or their parts that are involved in generating and responding to electrical charges.Hippocampus: A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation.Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Neural Inhibition: The function of opposing or restraining the excitation of neurons or their target excitable cells.Hospitals, County: Hospitals controlled by the county government.Pericardium: A conical fibro-serous sac surrounding the HEART and the roots of the great vessels (AORTA; VENAE CAVAE; PULMONARY ARTERY). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers.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.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Quinidine: An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Hydrogensulfite Reductase: An enzyme found primarily in SULFUR-REDUCING BACTERIA where it plays an important role in the anaerobic carbon oxidation pathway.Anemia: A reduction in the number of circulating ERYTHROCYTES or in the quantity of HEMOGLOBIN.Receptors, Catecholamine: Cell surface proteins that bind catecholamines with high affinity and trigger intracellular changes which influence the behavior of cells. The catecholamine messengers epinephrine, norepinephrine, and dopamine are synthesized from tyrosine by a common biosynthetic pathway.Ether-A-Go-Go Potassium Channels: A family of voltage-gated potassium channels that are characterized by long N-terminal and C-terminal intracellular tails. They are named from the Drosophila protein whose mutation causes abnormal leg shaking under ether anesthesia. Their activation kinetics are dependent on extracellular MAGNESIUM and PROTON concentration.Myocutaneous Flap: A mass of tissue, including skin and muscle, that has been cut away from surrounding areas for transplantation.Neurotransmitter Agents: Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.Barium: An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Urethral Neoplasms: Cancer or tumors of the URETHRA. Benign epithelial tumors of the urethra usually consist of squamous and transitional cells. Primary urethral carcinomas are rare and typically of squamous cells. Urethral carcinoma is the only urological malignancy that is more common in females than in males.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Lidocaine: A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Cesium: A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.Ganglia, Spinal: Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.Circadian Clocks: Biological mechanism that controls CIRCADIAN RHYTHM. Circadian clocks exist in the simplest form in cyanobacteria and as more complex systems in fungi, plants, and animals. In humans the system includes photoresponsive RETINAL GANGLION CELLS and the SUPRACHIASMATIC NUCLEUS that acts as the central oscillator.gamma-Aminobutyric Acid: The most common inhibitory neurotransmitter in the central nervous system.Electrocardiography: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.Differential Threshold: The smallest difference which can be discriminated between two stimuli or one which is barely above the threshold.Oscillometry: The measurement of frequency or oscillation changes.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Muscles: Contractile tissue that produces movement in animals.Amino Acid Transport System y+LSynaptic Potentials: The voltages across pre- or post-SYNAPTIC MEMBRANES.Strontium: An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.Commitment of Mentally Ill: Legal process required for the institutionalization of a patient with severe mental problems.Sodium-Calcium Exchanger: An electrogenic ion exchange protein that maintains a steady level of calcium by removing an amount of calcium equal to that which enters the cells. It is widely distributed in most excitable membranes, including the brain and heart.Sensory Receptor Cells: Specialized afferent neurons capable of transducing sensory stimuli into NERVE IMPULSES to be transmitted to the CENTRAL NERVOUS SYSTEM. Sometimes sensory receptors for external stimuli are called exteroceptors; for internal stimuli are called interoceptors and proprioceptors.Decapodiformes: A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.Azotemia: A biochemical abnormality referring to an elevation of BLOOD UREA NITROGEN and CREATININE. Azotemia can be produced by KIDNEY DISEASES or other extrarenal disorders. When azotemia becomes associated with a constellation of clinical signs, it is termed UREMIA.Nerve Fibers, Unmyelinated: A class of nerve fibers as defined by their nerve sheath arrangement. The AXONS of the unmyelinated nerve fibers are small in diameter and usually several are surrounded by a single MYELIN SHEATH. They conduct low-velocity impulses, and represent the majority of peripheral sensory and autonomic fibers, but are also found in the BRAIN and SPINAL CORD.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Cobalt: A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Ganglia: Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.Apamin: A highly neurotoxic polypeptide from the venom of the honey bee (Apis mellifera). It consists of 18 amino acids with two disulfide bridges and causes hyperexcitability resulting in convulsions and respiratory paralysis.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.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.Immunosorbents: An insoluble support for an ANTIGEN or ANTIBODIES that is used in AFFINITY CHROMATOGRAPHY to adsorb the homologous antibody or antigen from a mixture. Many different substances are used, among them SEPHAROSE; GLUTARALDEHYDE; copolymers of ANHYDRIDES; polyacrylamides, etc.Cochlear Nerve: The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.Ranvier's Nodes: Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.Isoproterenol: Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.Herb-Drug Interactions: The effect of herbs, other PLANTS, or PLANT EXTRACTS on the activity, metabolism, or toxicity of drugs.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Ovalbumin: An albumin obtained from the white of eggs. It is a member of the serpin superfamily.Bicuculline: An isoquinoline alkaloid obtained from Dicentra cucullaria and other plants. It is a competitive antagonist for GABA-A receptors.Shaw Potassium Channels: A shaker subfamily that is prominently expressed in NEURONS and are necessary for high-frequency, repetitive firing of ACTION POTENTIALS.Excitatory Amino Acid Antagonists: Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.Periodicity: The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Leukemia Virus, Murine: Species of GAMMARETROVIRUS, containing many well-defined strains, producing leukemia in mice. Disease is commonly induced by injecting filtrates of propagable tumors into newborn mice.Neuronal Plasticity: The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.Palau: A republic consisting of a group of about 100 islands and islets in the western Pacific Ocean. Its capital is Koror. Under Spain it was administered as a part of the Caroline Islands but was sold to Germany in 1899. Seized by Japan in 1914, it was taken by the Allies in World War II in 1944. In 1947 it became part of the U.S. Trust Territory of the Pacific Islands, became internally self-governing in 1980, obtained independent control over its foreign policy (except defense) in 1986, and achieved total independence October 1, 1994. (Webster's New Geographical Dictionary, 1988, p915; telephone communication with Randy Flynn, Board on Geographic Names, 17 January 1995)Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Oncogene Proteins v-erbB: Transforming proteins encoded by erbB oncogenes from the avian erythroblastosis virus. The protein is a truncated form of the EGF receptor (RECEPTOR, EPIDERMAL GROWTH FACTOR) whose kinase domain is constitutively activated by deletion of the ligand-binding domain.Ulnar Nerve: A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.Barium Compounds: Inorganic compounds that contain barium as an integral part of the molecule.Sarcoplasmic Reticulum: A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Head and Neck Neoplasms: Soft tissue tumors or cancer arising from the mucosal surfaces of the LIP; oral cavity; PHARYNX; LARYNX; and cervical esophagus. Other sites included are the NOSE and PARANASAL SINUSES; SALIVARY GLANDS; THYROID GLAND and PARATHYROID GLANDS; and MELANOMA and non-melanoma skin cancers of the head and neck. (from Holland et al., Cancer Medicine, 4th ed, p1651)Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Extracellular Space: Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.Gestrinone: A non-estrogenic contraceptive which is a weak progestin with strong anti-progesterone properties. It is effective if used once a week orally or can also be used in intravaginal devices.Calcium Channels, T-Type: A heterogenous group of transient or low voltage activated type CALCIUM CHANNELS. They are found in cardiac myocyte membranes, the sinoatrial node, Purkinje cells of the heart and the central nervous system.Monokines: Soluble mediators of the immune response that are neither antibodies nor complement. They are produced largely, but not exclusively, by monocytes and macrophages.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Cadmium: An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.Lymnaea: A genus of dextrally coiled freshwater snails that includes some species of importance as intermediate hosts of parasitic flukes.Nervous System Physiological Phenomena: Characteristic properties and processes of the NERVOUS SYSTEM as a whole or with reference to the peripheral or the CENTRAL NERVOUS SYSTEM.6-Cyano-7-nitroquinoxaline-2,3-dione: A potent excitatory amino acid antagonist with a preference for non-NMDA iontropic receptors. It is used primarily as a research tool.Anterior Spinal Artery Syndrome: Ischemia or infarction of the spinal cord in the distribution of the anterior spinal artery, which supplies the ventral two-thirds of the spinal cord. This condition is usually associated with ATHEROSCLEROSIS of the aorta and may result from dissection of an AORTIC ANEURYSM or rarely dissection of the anterior spinal artery. Clinical features include weakness and loss of pain and temperature sensation below the level of injury, with relative sparing of position and vibratory sensation. (From Adams et al., Principles of Neurology, 6th ed, pp1249-50)Torsades de Pointes: A malignant form of polymorphic ventricular tachycardia that is characterized by HEART RATE between 200 and 250 beats per minute, and QRS complexes with changing amplitude and twisting of the points. The term also describes the syndrome of tachycardia with prolonged ventricular repolarization, long QT intervals exceeding 500 milliseconds or BRADYCARDIA. Torsades de pointes may be self-limited or may progress to VENTRICULAR FIBRILLATION.Rhodanine2-Amino-5-phosphonovalerate: The D-enantiomer is a potent and specific antagonist of NMDA glutamate receptors (RECEPTORS, N-METHYL-D-ASPARTATE). The L form is inactive at NMDA receptors but may affect the AP4 (2-amino-4-phosphonobutyrate; APB) excitatory amino acid receptors.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Ryanodine: A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.Nerve Endings: Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.Thylakoids: Membranous cisternae of the CHLOROPLAST containing photosynthetic pigments, reaction centers, and the electron-transport chain. Each thylakoid consists of a flattened sac of membrane enclosing a narrow intra-thylakoid space (Lackie and Dow, Dictionary of Cell Biology, 2nd ed). Individual thylakoids are interconnected and tend to stack to form aggregates called grana. They are found in cyanobacteria and all plants.Electric Capacitance: The ability of a substrate to retain an electrical charge.KCNQ1 Potassium Channel: A voltage-gated potassium channel that is expressed primarily in the HEART.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.Small-Conductance Calcium-Activated Potassium Channels: A major class of calcium-activated potassium channels that are found primarily in excitable CELLS. They play important roles in the transmission of ACTION POTENTIALS and generate a long-lasting hyperpolarization known as the slow afterhyperpolarization.Acetanilides: Compounds based on N-phenylacetamide, that are similar in structure to 2-PHENYLACETAMIDES. They are precursors of many other compounds. They were formerly used as ANALGESICS and ANTIPYRETICS, but often caused lethal METHEMOGLOBINEMIA.Potassium Channels, Inwardly Rectifying: Potassium channels where the flow of K+ ions into the cell is greater than the outward flow.Anesthetics, Local: Drugs that block nerve conduction when applied locally to nerve tissue in appropriate concentrations. They act on any part of the nervous system and on every type of nerve fiber. In contact with a nerve trunk, these anesthetics can cause both sensory and motor paralysis in the innervated area. Their action is completely reversible. (From Gilman AG, et. al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed) Nearly all local anesthetics act by reducing the tendency of voltage-dependent sodium channels to activate.Brain Stem: The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.Voltage-Gated Sodium Channels: A family of membrane proteins that selectively conduct SODIUM ions due to changes in the TRANSMEMBRANE POTENTIAL DIFFERENCE. They typically have a multimeric structure with a core alpha subunit that defines the sodium channel subtype and several beta subunits that modulate sodium channel activity.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.Purkinje Cells: The output neurons of the cerebellar cortex.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Nerve Net: A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.Pentanols: Isomeric forms and derivatives of pentanol (C5H11OH).Spontaneous Combustion: A circumstance where a substance or organism takes fire and burns without an exogenous source. Spontaneous human combustion differs from preternatural human combustibility in that in the latter, some spark or trivial flame sets the fire and the body tissues, which have a greatly enhanced inflammability, continue to undergo incineration without any external heat source or combustible materials. (Bergman NA. Spontaneous human combustion: its role in literature and science. Pharos 1988;Fall;51(4):18-21)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.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Muscle Cells: Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Verapamil: A calcium channel blocker that is a class IV anti-arrhythmia agent.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Tubocurarine: A neuromuscular blocker and active ingredient in CURARE; plant based alkaloid of Menispermaceae.Veratridine: A benzoate-cevane found in VERATRUM and Schoenocaulon. It activates SODIUM CHANNELS to stay open longer than normal.Piperidines: A family of hexahydropyridines.KCNQ Potassium Channels: A family of delayed rectifier voltage-gated potassium channels that share homology with their founding member, KCNQ1 PROTEIN. KCNQ potassium channels have been implicated in a variety of diseases including LONG QT SYNDROME; DEAFNESS; and EPILEPSY.Strophanthidin: 3 beta,5,14-Trihydroxy-19-oxo-5 beta-card-20(22)-enolide. The aglycone cardioactive agent isolated from Strophanthus Kombe, S. gratus and other species; it is a very toxic material formerly used as digitalis. Synonyms: Apocymarin; Corchorin; Cynotoxin; Corchorgenin.Optics and Photonics: A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.Pyridinium CompoundsMollusca: A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.Hemorrhagic Disorders: Spontaneous or near spontaneous bleeding caused by a defect in clotting mechanisms (BLOOD COAGULATION DISORDERS) or another abnormality causing a structural flaw in the blood vessels (HEMOSTATIC DISORDERS).Mexiletine: Antiarrhythmic agent pharmacologically similar to LIDOCAINE. It may have some anticonvulsant properties.Chelating Agents: Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.Vagus Nerve: The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).Internal Medicine: A medical specialty concerned with the diagnosis and treatment of diseases of the internal organ systems of adults.Photogrammetry: Making measurements by the use of stereoscopic photographs.Literature: Writings having excellence of form or expression and expressing ideas of permanent or universal interest. The body of written works produced in a particular language, country, or age. (Webster, 3d ed)Elapid Venoms: Venoms from snakes of the family Elapidae, including cobras, kraits, mambas, coral, tiger, and Australian snakes. The venoms contain polypeptide toxins of various kinds, cytolytic, hemolytic, and neurotoxic factors, but fewer enzymes than viper or crotalid venoms. Many of the toxins have been characterized.LuxembourgGlutamic Acid: A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM.Avastrovirus: A genus of ASTROVIRIDAE infecting avian species and often involving extra-intestinal manifestations. The type species is Turkey astrovirus.Genes, MHC Class I: Genetic loci in the vertebrate major histocompatibility complex which encode polymorphic characteristics not related to immune responsiveness or complement activity, e.g., B loci (chicken), DLA (dog), GPLA (guinea pig), H-2 (mouse), RT-1 (rat), HLA-A, -B, and -C class I genes of man.Ganglia, Invertebrate: Clusters of neuronal cell bodies in invertebrates. Invertebrate ganglia may also contain neuronal processes and non-neuronal supporting cells. Many invertebrate ganglia are favorable subjects for research because they have small numbers of functional neuronal types which can be identified from one animal to another.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.Cardiac Complexes, Premature: A group of cardiac arrhythmias in which the cardiac contractions are not initiated at the SINOATRIAL NODE. They include both atrial and ventricular premature beats, and are also known as extra or ectopic heartbeats. Their frequency is increased in heart diseases.Genome, Protozoan: The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.Sarcolemma: The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Caffeine: A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.QuinoxalinesFerrets: Semidomesticated variety of European polecat much used for hunting RODENTS and/or RABBITS and as a laboratory animal. It is in the subfamily Mustelinae, family MUSTELIDAE.Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Jehovah's Witnesses: Members of a religious denomination founded in the United States during the late 19th century in which active evangelism is practiced, the imminent approach of the millennium is preached, and war and organized government authority in matters of conscience are strongly opposed (from American Heritage Dictionary of the English Language, 4th ed). Jehovah's Witnesses generally refuse blood transfusions and other blood-based treatments based on religious belief.