Electric Stimulation: Use of electric potential or currents to elicit biological responses.Electric Stimulation Therapy: Application of electric current in treatment without the generation of perceptible heat. It includes electric stimulation of nerves or muscles, passage of current into the body, or use of interrupted current of low intensity to raise the threshold of the skin to pain.Cochlear Implants: Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.Chiroptera: Order of mammals whose members are adapted for flight. It includes bats, flying foxes, and fruit bats.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.Visual Prosthesis: Artificial device such as an externally-worn camera attached to a stimulator on the RETINA, OPTIC NERVE, or VISUAL CORTEX, intended to restore or amplify vision.Acoustic Stimulation: Use of sound to elicit a response in the nervous system.Auditory Pathways: NEURAL PATHWAYS and connections within the CENTRAL NERVOUS SYSTEM, beginning at the hair cells of the ORGAN OF CORTI, continuing along the eighth cranial nerve, and terminating at the AUDITORY CORTEX.Electric Organ: In about 250 species of electric fishes, modified muscle fibers forming disklike multinucleate plates arranged in stacks like batteries in series and embedded in a gelatinous matrix. A large torpedo ray may have half a million plates. Muscles in different parts of the body may be modified, i.e., the trunk and tail in the electric eel, the hyobranchial apparatus in the electric ray, and extrinsic eye muscles in the stargazers. Powerful electric organs emit pulses in brief bursts several times a second. They serve to stun prey and ward off predators. A large torpedo ray can produce of shock of more than 200 volts, capable of stunning a human. (Storer et al., General Zoology, 6th ed, p672)Cochlear Implantation: Surgical insertion of an electronic hearing device (COCHLEAR IMPLANTS) with electrodes to the COCHLEAR NERVE in the inner ear to create sound sensation in patients with residual nerve fibers.Auditory Cortex: The region of the cerebral cortex that receives the auditory radiation from the MEDIAL GENICULATE BODY.Deafness: A general term for the complete loss of the ability to hear from both ears.Inferior Colliculi: The posterior pair of the quadrigeminal bodies which contain centers for auditory function.Pitch Perception: A dimension of auditory sensation varying with cycles per second of the sound stimulus.Auditory Threshold: The audibility limit of discriminating sound intensity and pitch.Hearing: The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Psychoacoustics: The science pertaining to the interrelationship of psychologic phenomena and the individual's response to the physical properties of sound.Neuronal Plasticity: The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.Cochlea: The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Speech Perception: The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes).Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.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)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Electromagnetic Fields: Fields representing the joint interplay of electric and magnetic forces.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.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.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.Gymnotiformes: An order of neotropical electric fish found chiefly in the waters of South America. They continually emit weak electric discharges, which they use in object location and communication. A most popular species of research interest is the electric eel, ELECTROPHORUS electricus.Electric Injuries: Injuries caused by electric currents. The concept excludes electric burns (BURNS, ELECTRIC), but includes accidental electrocution and electric shock.Stimulation, Chemical: The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.Deep Brain Stimulation: Therapy for MOVEMENT DISORDERS, especially PARKINSON DISEASE, that applies electricity via stereotactic implantation of ELECTRODES in specific areas of the BRAIN such as the THALAMUS. The electrodes are attached to a neurostimulator placed subcutaneously.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Transcranial Magnetic Stimulation: A technique that involves the use of electrical coils on the head to generate a brief magnetic field which reaches the CEREBRAL CORTEX. It is coupled with ELECTROMYOGRAPHY response detection to assess cortical excitability by the threshold required to induce MOTOR EVOKED POTENTIALS. This method is also used for BRAIN MAPPING, to study NEUROPHYSIOLOGY, and as a substitute for ELECTROCONVULSIVE THERAPY for treating DEPRESSION. Induction of SEIZURES limits its clinical usage.Electric Wiring: An arrangement of wires distributing electricity.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.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.Electroporation: A technique in which electric pulses of intensity in kilovolts per centimeter and of microsecond-to-millisecond duration cause a temporary loss of the semipermeability of CELL MEMBRANES, thus leading to ion leakage, escape of metabolites, and increased uptake by cells of drugs, molecular probes, and DNA.Electric Power Supplies: Devices that control the supply of electric current for running electrical equipment.Torpedo: A genus of the Torpedinidae family consisting of several species. Members of this family have powerful electric organs and are commonly called electric rays.Electric Impedance: The resistance to the flow of either alternating or direct electrical current.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.Burns, Electric: Burns produced by contact with electric current or from a sudden discharge of electricity.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Kinetics: The rate dynamics in chemical or physical systems.Electrochemotherapy: A treatment modality that uses pulsed electrical currents to permeabilize cell membranes (ELECTROPORATION) and thereby enhance the uptake of chemotherapeutic agents, vaccines, or genes into the body's cells.Transcutaneous Electric Nerve Stimulation: The use of specifically placed small electrodes to deliver electrical impulses across the SKIN to relieve PAIN. It is used less frequently to produce ANESTHESIA.Electrophorus: A genus of fish, in the family GYMNOTIFORMES, capable of producing an electric shock that immobilizes fish and other prey. The species Electrophorus electricus is also known as the electric eel, though it is not a true eel.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.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).Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.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.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Animal Communication: Communication between animals involving the giving off by one individual of some chemical or physical signal, that, on being received by another, influences its behavior.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.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.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.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).Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.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)Evoked Potentials, Motor: The electrical response evoked in a muscle or motor nerve by electrical or magnetic stimulation. Common methods of stimulation are by transcranial electrical and TRANSCRANIAL MAGNETIC STIMULATION. It is often used for monitoring during neurosurgery.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.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.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.Birefringence: The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.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.Motor Cortex: Area of the FRONTAL LOBE concerned with primary motor control located in the dorsal PRECENTRAL GYRUS immediately anterior to the central sulcus. It is comprised of three areas: the primary motor cortex located on the anterior paracentral lobule on the medial surface of the brain; the premotor cortex located anterior to the primary motor cortex; and the supplementary motor area located on the midline surface of the hemisphere anterior to the primary motor cortex.Lymphocyte Activation: Morphologic alteration of small B LYMPHOCYTES or T LYMPHOCYTES in culture into large blast-like cells able to synthesize DNA and RNA and to divide mitotically. It is induced by INTERLEUKINS; MITOGENS such as PHYTOHEMAGGLUTININS, and by specific ANTIGENS. It may also occur in vivo as in GRAFT REJECTION.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.Atropine: An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Norepinephrine: Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.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.Mice, Inbred C57BLIsoproterenol: 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.Magnetics: The study of MAGNETIC PHENOMENA.Power Plants: Units that convert some other form of energy into electrical energy.Muscles: Contractile tissue that produces movement in animals.Neural Inhibition: The function of opposing or restraining the excitation of neurons or their target excitable cells.Evoked Potentials, Somatosensory: The electric response evoked in the CEREBRAL CORTEX by stimulation along AFFERENT PATHWAYS from PERIPHERAL NERVES to CEREBRUM.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Sympathetic Nervous System: The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Electroshock: Induction of a stress reaction in experimental subjects by means of an electrical shock; applies to either convulsive or non-convulsive states.Receptors, Cholinergic: Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Subthalamic Nucleus: Lens-shaped structure on the inner aspect of the INTERNAL CAPSULE. The SUBTHALAMIC NUCLEUS and pathways traversing this region are concerned with the integration of somatic motor function.Electromagnetic Phenomena: Characteristics of ELECTRICITY and magnetism such as charged particles and the properties and behavior of charged particles, and other phenomena related to or associated with electromagnetism.Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Reaction Time: The time from the onset of a stimulus until a response is observed.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.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.Enzyme Inhibitors: Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.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.Motor Neurons: Neurons which activate MUSCLE CELLS.Self Stimulation: Stimulation of the brain, which is self-administered. The stimulation may result in negative or positive reinforcement.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.Sensation: The process in which specialized SENSORY RECEPTOR CELLS transduce peripheral stimuli (physical or chemical) into NERVE IMPULSES which are then transmitted to the various sensory centers in the CENTRAL NERVOUS SYSTEM.Skates (Fish): The common name for all members of the Rajidae family. Skates and rays are members of the same order (Rajiformes). Skates have weak electric organs.Carbachol: A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Parasympathetic Nervous System: The craniosacral division of the autonomic nervous system. The cell bodies of the parasympathetic preganglionic fibers are in brain stem nuclei and in the sacral spinal cord. They synapse in cranial autonomic ganglia or in terminal ganglia near target organs. The parasympathetic nervous system generally acts to conserve resources and restore homeostasis, often with effects reciprocal to the sympathetic nervous system.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.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.Fishes: A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.Transfection: The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.Electrophoresis: An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current.T-Lymphocytes: Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Cell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.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)Biophysical Phenomena: The physical characteristics and processes of biological systems.Protein Kinase C: An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.

*  Effect of continuous electrical stimulation on retinal structure and function :: University of Southern California...
Effect of continuous electrical stimulation on retinal structure and function. Page 1. Save page Remove page Previous. 1 of 195 ... Electrical stimulation of the central nervous system albeit an unnatural way, has been found to be an effective way of causing ... EFFECT OF CONTINUOUS ELECTRICAL STIMULATION ON RETINAL STRUCTURE AND FUNCTION by Aditi Ray A Dissertation Presented to the ... EFFECT OF CONTINUOUS ELECTRICAL STIMULATION ON RETINAL STRUCTURE AND FUNCTION by Aditi Ray A Dissertation Presented to the ...
*  Brevet US20080097541 - Apparatus and method for spatially and temporally distributing cardiac ... - Google Brevets
In order to spatially and temporally distribute the stimulation, the pulses are delivered through a switchable pulse output ... A cardiac electro-stimulatory device and method for operating same in which stimulation pulses are distributed among a ... System, adaptor and method to provide medical electrical stimulation. US5800464 *. 3 oct. 1996. 1 sept. 1998. Medtronic, Inc.. ... Apparatus and method for reversal of myocardial remodeling with electrical stimulation. US6640135 *. 6 avr. 2000. 28 oct. 2003 ...
*  Patent EP1172125B1 - An implantable heart stimulation system with automatic mode switching ... - Google Patentsuche
It is the function of a pacemaker to provide electrical stimulation pulses to the appropriate chamber(s) of the heart (atria or ... An implantable heart stimulation system with automatic mode switching controlled by sympatho-vagal balance. EP 1172125 B1 ... Adaptive baroreflex stimulation therapy for disordered breathing. US7938782. 12. Mai 2008. 10. Mai 2011. Cardiac Pacemakers, ... An implantable heart-stimulation system (10) having sensing elements (12, 13) for sensing atrial and ventricular signals, a ...
*  WEB SITE] Study shows continuous electrical stimulation suppresses seizures in patients with epilepsy. | TBI Rehabilitation
Unfortunately, typical approaches, such as vagal nerve stimulation or responsive nerve stimulation, rarely stop seizures ... electrical stimulation of the brain has been a treatment of last resort. ... disability driving drop foot education EEG elbow Electrical Stimulation electrical stimulation therapy Electric stimulation ... the grid of electrical contacts was used for stimulation at levels the patient would not notice. If the stimulation provided ...
*  The Neurocritic: Bad news for DARPA's RAM program: Electrical Stimulation of Entorhinal Region Impairs Memory
There are so many questions about what direct electrical stimulation actually does, and what the best parameters (stimulation ... 2012) began by reviewing all the potential benefits of entorhinal stimulation:. In rodents, electrical stimulation of the ... It has also been shown that electrical stimulation can enhance neurogenesis in the hippocampus. Whether direct stimulation of ... electrical stimulation (at 50 Hz) was delivered to the EC or hippocampus. No stimulation was given in block 4.. Spatial ...
*  Direct electrical stimulation of human cortex: the gold standard for mapping brain functions? :: MPG.PuRe
Direct electrical stimulation of human cortex: the gold standard for mapping brain functions? ... Direct electrical stimulation of human cortex: the gold standard for mapping brain functions? ... Borchers, S., Himmelbach M, Logothetis, N., & Karnath, H. (2012). Direct electrical stimulation of human cortex: the gold ... Although we understand several aspects of electrical stimulation at the cellular level, surface DES evokes a complex summation ...
*  Patent US5797970 - System, adaptor and method to provide medical electrical stimulation - Google Patents
... of the leads such that electrical stimulation of a first amplitude is not passed through the diode while electrical stimulation ... diode which directs electrical stimulation pulses of a first amplitude to the first lead and directs electrical stimulation ... the means for directing electrical stimulation pulses coupled to the pulse generator. In the preferred embodiment the diode is ... the pulse generator generating electrical stimulation pulses of a first amplitude and a second amplitude, first and second ...
*  New & Used Ultrasound and Electrical Stimulation Unit | Buy Used Ultrasound and Electrical Stimulation Unit Equipment
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*  Gastric electrical stimulation - Wikipedia
Gastric electrical stimulation is a pacemaker-like device with electrical connections to the surface of the stomach. The device ... Gastric electrical stimulation, also known as implantable gastric stimulation, is the use of specific devices to provide ... Levinthal, DJ; Bielefeldt, K (January 2017). "Systematic review and meta-analysis: Gastric electrical stimulation for ... Chiu, JD; Soffer, E (January 2015). "Gastric electrical stimulation for obesity". Current gastroenterology reports. 17 (1): 424 ...
*  Brain Power Boosted With Electrical Stimulation - Slashdot
Submission: Brain Power Boosted With Electrical Stimulation. DARPA Investing In Electric Brain Stimulation To Train Snipers ... Brain Power Boosted With Electrical Stimulation 153 Posted by samzenpus on Thursday September 22, 2011 @12:19AM. from the power ... I know that exercise helps brain function but shocking somebody in the head with an electrical probe isn't a very nice way to ... Brain Power Boosted With Electrical Stimulation More Login Brain Power Boosted With Electrical Stimulation. Archived Discussion ...
*  Electrical Stimulation May Relieve Gastroparesis
Electrical stimulation (ES) at specific acupuncture points could relieve gastroparesis symptoms associated with diabetes, such ... Home / Specialties / Gastroenterology / Electrical Stimulation May Relieve Gastroparesis. Electrical Stimulation May Relieve ... Electrical stimulation (ES) at specific acupuncture points could relieve gastroparesis symptoms associated with diabetes, such ... Electrical stimulation was performed via surface ECG electrodes placed at acupoints PC6 and ST36 using pulse trains. Sham-ES ...
*  Electric Stimulation Could Help You Control Your Dreams - Slashdot
Submission + - Electric Stimulation Could Help You Control Your Dreams (sciencemag.org) Submitted by sciencehabit on Sunday May ... Electric Stimulation Could Help You Control Your Dreams. Archived Discussion. Load All Comments ... researchers applied electrical current to their skulls near the forehead and temples. This boosted neural activity in the ...
*  ASMBS: Electrical Stimulation Helps Diabetes, Obesity | Medpage Today
Source Reference: Bohdjalian A, et al, "The Tantalus meal-activated gastric electrical stimulation improves glycemic control in ... Vagal nerve stimulation led to HbA1c reductions approaching 2% in a smaller study reported at the meeting. Originally developed ... A second report at the meeting showed that vagal nerve stimulation induced HbA1c reductions that averaged 1.4% at one month, ... Explain to patients that two different types of implantable electrical stimulators improved diabetes control and induced weight ...
*  Can creativity be boosted through electrical stimulation?
One group of scientists state they have found a way to improve creativity through brain stimulation. ... Is it possible to boost creativity by applying electrical stimulation to the brain? ... More about Creativity, Brain, electrical brain stimulation, Psychology More news from Creativity. Brain. electrical brain sti ... Electrical brain stimulation is a form of electrotherapy and technique used in research and clinical neurobiology to stimulate ...
*  Non-pacing Electric Stimulation for Heart Failure | Medgadget
A report via PRNewswire on a cardiac stimulation system from Impulse Diagnostics, Inc, which has just started Phase II trials: ... Non-pacing Electric Stimulation for Heart Failure. April 19th, 2005 Nicholas Genes Cardiology, Critical Care ... A report via PRNewswire on a cardiac stimulation system from Impulse Diagnostics, Inc, which has just started Phase II trials: ... It seems novel to use electricty for a purpose other than pacing - but they've got data showing nonstimulatory electric pulses ...
*  Patent US5336255 - Electrical stimulation heat/cool pack - Google Patents
An electrical stimulation heat/cool pack includes a nonconductive pouch and straps for positioning and holding the ... Muscle- and nerve stimulation system has transcutaneous electrical nerve stimulation- electro muscle stimulation device with ... The present invention is directed to an electrical stimulation heat/cold pack in which the electrical distribution portion of ... Electrical stimulation electrode. US4887614 *. Apr 18, 1989. Dec 19, 1989. Kureha Kagaku Kogyo Kabushiki Kaisha. Medical ...
*  Electrical Stimulation Units cheap price
Get the best prices on electrical stimulation units, electrotherapy accessories, neuromuscular stimulators accessories, ... ELECTRICAL STIMULATION UNITS. Home » Medical Supplies & Equipment » Electrotherapy & Accessories » Electrical Stimulation Units ... The pencil electrode is used for manual stimulation procedures where pin-po ... ...
*  Electrical stimulation of brain alters dreams: study - NY Daily News
Electrical stimulation of brain enables 'lucid dreaming,' new study finds. Electrical stimulation of brain alters dreams: study ... Scientists said they had used a harmless electrical current to modify sleep so that an individual has 'lucid dreams,' a ... The study, reported in the journal Nature Neuroscience, found that a harmless electrical current could bring on 'lucid dreaming ... However, brain stimulation should always be carefully monitored by a physician,' she cautioned. ...
*  Electrical stimulation (epidural) of the spinal cord
... Funded in: 2006, 2007. Back to overview Networks of nerve cells located ... Previous research has shown that the musclecontrolling networks can be reactivated by external electrical stimulation of the ... control over the leg musculature to walk a few steps or to stand up from their wheelchair by means of electrical stimulation.. ... The control only works if it continuously receives electrical signals from the brain. In patients with paraplegia, the nerve ...
*  Subconvulsive Electrical Stimulation in Treatment of Chronic Neurosis | The BMJ
Subconvulsive Electrical Stimulation in Treatment of Chronic Neurosis Br Med J 1952; 2 :1170 ... Subconvulsive Electrical Stimulation in Treatment of Chronic Neurosis. Br Med J 1952; 2 doi: https://doi.org/10.1136/bmj.2.4795 ...
*  Patent US5038796 - Electrical stimulation electrode with impedance compensation - Google Patents
Further adjustment of the electrical conductivity may also be achieved by varying the conductivity of individual fibers ... and electrical shunt means disposed along the conductive material for causing more uniform resistivity between any two equally ... A flexible transcutaneous electrical nerve and/or muscle stimulation electrode is provided which utilizes a conductive material ... spaced apart points on the conductive material than without the electrical shunt means. ...
*  Neuromuscular Electrical Stimulation Therapy for Swallowing | Sinai
Neuromuscular electrical stimulation (NMES)is used to restore swallowing function and strength and any other types of ... Neuromuscular Electrical Stimulation Therapy for Swallowing Neuromuscular electrical stimulation (NMES) can be used in ... Sinai , Sinai Rehabilitation Center , Outpatient Rehabilitation Services , Neuromuscular Electrical Stimulation Therapy for ... An external electrical impulse is a modality combined with traditional swallowing exercises to restore swallowing function and ...
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In addition to our wide selection of electrical stimulation units, you can choose from different types of products to customize ... electrical stimulation units, electrotherapy accessories, neuromuscular stimulators accessories, peripheral nerve stimulators ... MSEC offers a variety of electrical stimulation units, ... Designed for therapeutic stimulation of nerves and muscles in ... ELECTRICAL STIMULATION UNITS. Home » Medical Supplies & Equipment » Electrotherapy & Accessories » Electrical Stimulation Units ...
*  Electric stimulation of brain releases powerful, opiate-like painkiller
... Thursday, January 3, 2013. Brain (Credit: Jens Langner ... This suggests that repetitive electrical stimulation over several sessions are required to have a lasting effect on clinical ... Next, researchers will investigate long-term effects of electric stimulation on the brain and find specific targets in the ... The stimulation is called transcranial direct current stimulation (tDCS).. The radiotracer was specifically designed to measure ...
*  Electrical Stimulation Improves Paralyzed Patients' Function
Electrical stimulation, a treatment first developed in the 1960s to treat pain, has been studied as a means to restore movement ... Electrical Stimulation Improves Paralyzed Patients' Function. By Sep 15, 2017 - 10:28:00 AM. ... Electrical stimulation may be most effective for SCI-related paralysis when combined with physical therapy and medications that ... A review of more than 90 studies found that electrical stimulation may help restore function in those paralyzed after SCI. The ...

Cortical stimulation mapping: Cortical stimulation mapping (often shortened to CSM) is a type of electrocorticography that involves a physically invasive procedure and aims to localize the function of specific brain regions through direct electrical stimulation of the cerebral cortex. It remains one of the earliest methods of analyzing the brain and has allowed researchers to study the relationship between cortical structure and systemic function.Sensory stimulation therapy: Sensory stimulation therapy (SST) is an experimental therapy that aims to utilize neural plasticity mechanisms to aid in the recovery of somatosensory function after stroke or cognitive ageing. Stroke and cognitive ageing are well known sources of cognitive loss, the former by neuronal death, the later by weakening of neural connections.Horseshoe bat: Horseshoe bats make up the bat family Rhinolophidae. In addition to the single living genus, Rhinolophus, one extinct genus, Palaeonycteris, has been recognized.Photovoltaic retinal prosthesis: Photovoltaic retinal prosthesis is a technology for restoring sight to blind patients suffering from degenerative retinal diseases. In retinal degenerative diseases such as Retinitis Pigmentosa and Age-Related Macular Degeneration, patients loss ‘image capturing’ photo-receptors, but, neurons in the ‘image-processing’ inner retinal layers are relatively well preserved.Blind electric rayPrelingual deafness: A prelingual deaf individual is someone who was born with a hearing loss, or whose hearing loss occurred before they began to speak. Infants usually start saying their first words around one year.Pitch spaceEquivalent rectangular bandwidth: The equivalent rectangular bandwidth or ERB is a measure used in psychoacoustics, which gives an approximation to the bandwidths of the filters in human hearing, using the unrealistic but convenient simplification of modeling the filters as rectangular band-pass filters.Psychoacoustics: Psychoacoustics is the scientific study of sound perception. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound (including speech and music).Homeostatic plasticity: In neuroscience, homeostatic plasticity refers to the capacity of neurons to regulate their own excitability relative to network activity, a compensatory adjustment that occurs over the timescale of days. Synaptic scaling has been proposed as a potential mechanism of homeostatic plasticity.Ventricular action potentialReference electrode: A reference electrode is an electrode which has a stable and well-known electrode potential. The high stability of the electrode potential is usually reached by employing a redox system with constant (buffered or saturated) concentrations of each participants of the redox reaction.Cats in the United States: Many different species of mammal can be classified as cats (felids) in the United States. These include domestic cat (both house cats and feral), of the species Felis catus; medium-sized wild cats from the genus Lynx; and big cats from the genera Puma and Panthera.Temporal analysis of products: Temporal Analysis of Products (TAP), (TAP-2), (TAP-3) is an experimental technique for studyingElectromagnetic environment: In telecommunication, the term electromagnetic environment (EME) has the following meanings:Periodic current reversalHSD2 neurons: HSD2 neurons are a small group of neurons in the brainstem which are uniquely sensitive to the mineralocorticosteroid hormone aldosterone, through expression of HSD11B2. They are located within the caudal medulla oblongata, in the nucleus of the solitary tract (NTS).New Zealand rabbitBioelectrogenesis: Bioelectrogenesis is the generation of electricity by living organisms, a phenomenon that belongs to the science of electrophysiology. The nerve impulse is a bioelectric event.Chicago Electrical Trauma Research Institute: The Chicago Electrical Trauma Research Institute(CETRI) |url=http://www.cetri.NeurostimulationNeurotechnology: Neurotechnology is any technology that has a fundamental influence on how people understand the brain and various aspects of consciousness, thought, and higher order activities in the brain. It also includes technologies that are designed to improve and repair brain function and allow researchers and clinicians to visualize the brain.Overhead power line: An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large distances. It consists of one or more conductors (commonly multiples of three) suspended by towers or poles.Electrical conductivity meterGene electrotransfer: Gene electrotransfer is a versatile biotechnology technique that enables the transfer of genetic material into prokaryotic or eukaryotic cells. It is based on a physical method named electroporation, where a transient increase in the permeability of cell membrane is achieved when submitted to short and intense electric pulses, thus enabling the transport of large molecules (naked plasmid DNA, antisense oligonucleotides, siRNA) into cells that otherwise cannot permeate through the cell membrane.Proton exchange membrane fuel cellTorpedo ram: A torpedo ram is a type of torpedo boat combining a ram with torpedo tubes. Incorporating design elements from the cruiser and the monitor, it was intended to provide small and inexpensive weapon systems for coastal defence and other littoral combat.Jakob SegalCalcium signaling: Calcium ions are important for cellular signalling, as once they enter the cytosol of the cytoplasm they exert allosteric regulatory effects on many enzymes and proteins. Calcium can act in signal transduction resulting from activation of ion channels or as a second messenger caused by indirect signal transduction pathways such as G protein-coupled receptors.Burst kinetics: Burst kinetics is a form of enzyme kinetics that refers to an initial high velocity of enzymatic turnover when adding enzyme to substrate. This initial period of high velocity product formation is referred to as the "Burst Phase".Electroanalgesia: Electroanalgesia is a form of analgesia, or pain relief, that uses electricity to ease pain. Electrical devices can be internal or external, at the site of pain (local) or delocalized throughout the whole body.Pentameric protein: A pentameric protein is a quaternary protein structure that consists of five protein subunits. These sub-units come together to form a channel.Reversal potential: In a biological membrane, the reversal potential (also known as the Nernst potential) of an ion is the membrane potential at which there is no net (overall) flow of that particular ion from one side of the membrane to the other. In the case of post-synaptic neurons, the reversal potential is the membrane potential at which a given neurotransmitter causes no net current flow of ions through that neurotransmitter receptor's ion channel.Bipolar electrochemistry: Bipolar electrochemistry is a phenomenon in electrochemistry based on the polarization of conducting objects in electric fields. Indeed, this polarization generates a potential difference between the two extremities of the substrate that is equal to the electric field value multiplied by the size of the object.Muscle contraction: Muscle contraction is the activation of tension-generating sites within muscle fibers. In physiology, muscle contraction does not mean muscle shortening because muscle tension can be produced without changes in muscle length such as holding a heavy book or a dumbbell at the same position.Master of Advanced Studies in Interaction Design (MAIND), SUPSIHyperphosphorylation: Hyperphosphorylation occurs when a biochemical with multiple phosphorylation sites is fully saturated. Hyperphosphorylation is one of the signalling mechanisms used by the cell to regulate mitosis.Concentration effect: In the study of inhaled anesthetics, the concentration effect is the increase in the rate that the Fa(alveolar concentration)/Fi(inspired concentration) ratio rises as the alveolar concentration of that gas is increased. In simple terms, the higher the concentration of gas administered, the faster the alveolar concentration of that gas approaches the inspired concentration.Cell membraneCephalic phase: The cephalic phase of gastric secretion occurs even before food enters the stomach, especially while it is being eaten. It results from the sight, smell, thought, or taste of food, and the greater the appetite, the more intense is the stimulation.Multielectrode array: Multielectrode arrays (MEAs) or microelectrode arrays are devices that contain multiple plates or shanks through which neural signals are obtained or delivered, essentially serving as neural interfaces that connect neurons to electronic circuitry. There are two general classes of MEAs: implantable MEAs, used in vivo, and non-implantable MEAs, used in vitro.Matrix model: == Mathematics and physics ==Mature messenger RNA: Mature messenger RNA, often abbreviated as mature mRNA is a eukaryotic RNA transcript that has been spliced and processed and is ready for translation in the course of protein synthesis. Unlike the eukaryotic RNA immediately after transcription known as precursor messenger RNA, it consists exclusively of exons, with all introns removed.Inyoite: BO)(OH)·4(HO)Aging movement control: Normal aging movement control in humans is about the changes on the muscles, motor neurons, nerves, sensory functions, gait, fatigue, visual and manual responses, in men and women as they get older but who do not have neurological, muscular (atrophy, dystrophy...) or neuromuscular disorder.Outline of biophysics: The following outline is provided as an overview of and topical guide to biophysics:A. N. Hartley: Annie Norah Hartley (1902 – 1994), usually known simply as Norah Hartley, was a dog breeder and the first female board member of the Kennel Club.Crosstalk (biology): Biological crosstalk refers to instances in which one or more components of one signal transduction pathway affects another. This can be achieved through a number of ways with the most common form being crosstalk between proteins of signalling cascades.Withdrawal reflex: The withdrawal reflex (nociceptive or flexor withdrawal reflex) is a spinal reflex intended to protect the body from damaging stimuli. It is polysynaptic, causing stimulation of sensory, association, and motor neurons.Neutron magnetic moment: The neutron magnetic moment is the intrinsic magnetic dipole moment of the neutron, symbol μn. Protons and neutrons, both nucleons, comprise the nucleus of atoms, and both nucleons behave as small magnets whose strengths are measured by their magnetic moments.Miljacka Hydroelectric Power Plant: 230px|thumb|right|Miljacka Hydroelectric Power Plant.Kennel clubMyokine: A myokine is one of several hundred cytokines or other small proteins (~5–20 kDa) and proteoglycan peptides that are produced and released by muscle cells (myocytes) in response to muscular contractions.Bente Klarlund Pedersen , Thorbjörn C.Electroshock (wrestler)Coles PhillipsElectromagnetic navigation bronchoscopy: ENB (Electromagnetic Navigation Bronchoscopy) or EMN bronchoscopy is a medical procedure utilizing electromagnetic technology designed to localize and guide endoscopic tools or catheters through the bronchial pathways of the lung. Using a virtual, three-dimensional (3D) bronchial map from a recently computed tomography (CT) chest scan and disposable catheter set, physicians are able to navigate to a desired location within the lung to biopsy lesions, stage lymph nodes, insert markers to guide radiotherapy or guide brachytherapy catheters.Neuromere: Neuromeres are morphologically or molecularly defined transient segments of the early developing brain. Rhombomeres are such segments that make up the rhombencephalon or hindbrain.

(1/19053) Inhibitory innervation of cat sphincter of Oddi.

1 Electrical stimulation with trains of 0.1-0.2 ms pulses of the cat isolated sphincter of Oddi inhibited the spontaneous contractile activity and lowered base-line tension considerably. A contraction usually followed the period of stimulation. 2 These inhibitory effects were prevented by tetrodotoxin 0.1-0.5 mug/ml but were not reduced by hexamethonilm, morphine, or blockade of alpha- or beta-adrenoreceptors of cholinoceptors with phenoxy-benzamine propranolol or atropine, respectively. 3 Adenosine-5'-triphosphate (ATP) and adenosine-5'-diphosphate (ADP) inhibited the spontaneous sphincter activity and caused relaxation thus mimicking the effects of the C-terminal octapeptide of cholecystokinin (C8-CCK), isoprenaline and prostaglandin E1 and E2. 4 ATP alone (greater than 100 mug/ml) or ATP (greater than 10 mug/ml) plus dipyridamole (1 mug/ml), relaxed the sphincter to the same degrees as did the field stimulation. 5 In sphincter maximally contracted by acetylcholine, the effect of stimulation was more marked than that recorded in uncontracted preparations. 6 The present findings suggest that the sphincter of Oddi receives inhibitory nerves that are neither cholinergic nor adrenergic.  (+info)

(2/19053) Further evidence that prostaglandins inhibit the release of noradrenaline from adrenergic nerve terminals by restriction of availability of calcium.

1 Guinea-pig vasa deferentia were continuously superfused after labelling the transmitter stores with [3H](-)-noradrenaline. Release of [3H]-(-)-noradrenaline was induced by transmural nerve stimulation. 2 Prostglandin E2 (14 nM) drastically reduced the release of [3H]-(-)-noradrenaline, while tetraethylammonium (2 mM), rubidium (6 mM), phenoxybenzamine (3 muM) each in the presence or absence of Uptake 1 or 2 blockade, and prolonged pulse duration (from 0.5 to 2.0 ms) all significantly increased the release of [3H]-(-)-noradrenaline per nerve impulse. 3 The inhibitory effect of prostaglandin E2 on evoked release of [3H]-(-)-noradrenaline was significantly reduced by tetraethylammonium, rubidium and prolonged pulse duration, whilst it was actually enhanced by phenoxybenzamine. This indicates that increased release of noradrenaline per nerve impulse does not per se counteract the inhibitory effect of prostaglandin E2. 4 It is concluded that tetraethylammonium, rubidium and prolonged pulse duration counteracted the inhibitory effect of prostaglandin E2 on T3H]-(-)-noradrenaline release by promoting calcium influx during the nerve action potential. The results are consistent with, and add more weight to the view that prostaglandins inhibit the release of noradrenaline by restriction of calcium availability.  (+info)

(3/19053) Automatic activity in depolarized guinea pig ventricular myocardium. Characteristics and mechanisms.

Membrane potential was changed uniformly in segments, 0.7-1.0 mm long, of guinea pig papillary muscles excised from the right ventricle by using extracellular polarizing current pulses applied across two electrically insulated cf preparations superfused with Tyrode's solution at maximum diastolic membrane potentials ranging from-35.2+/-7.5 (threshold) to +4.0+/-9.2 mV. The average maximum dV/dt of RAD ranged from 17.1 to 18.0 V/sec within a membrane potential range of -40 to +20 mV. Raising extracellular Ca2+ concentration [Ca2+]0 from 1.8 to 6.8 mM, or application of isoproterenol (10(-6)g/ml) enhanced the rate of RAD, but lowering [Ca2+]0 to 0.4 mM or exposure to MnCl2 (6 mM) abolished RAD. RAD were enhanced by lowering extracellular K+ concentration [K+]0 from 5.4 to 1.5 mM. RAD were suppressed in 40% of fibers by raising [K+]0 to 15.4 mM, and in all fibers by raising [K+]0 to 40.4 mM. This suppression was due to increased [K+]0 and not to K-induced depolarization because it persisted when membrane potential was held by means of a conditioning hyperpolarizing puled gradually after maximum repolarization. These observations suggest that the development of RAD in depolarized myocardium is associated with a time-dependent decrease in outward current (probably K current) and with increase in the background inward current, presumably flowing through the slow cha-nel carrying Ca or Na ions, or both.  (+info)

(4/19053) Reduction in baroreflex cardiovascular responses due to venous infusion in the rabbit.

We studied reflex bradycardia and depression of mean arterial blood pressure (MAP) during left aortic nerve (LAN) stimulation before and after volume infusion in the anesthetized rabbit. Step increases in mean right atrial pressure (MRAP) to 10 mm Hg did not result in a significant change in heart rate or MAP. After volume loading, responses to LAN stimulation were not as great and the degree of attenuation was propoetional to the level of increased MRAP. A change in responsiveness was observed after elevation of MRAP by only 1 mm Hg, corresponding to less than a 10% increase in average calculated blood volume. after an increase in MRAP of 10 mm Hg, peak responses were attenuated by 44% (heart rate) and 52% (MAP), and the initial slopes (rate of change) were reduced by 46% (heart rate) and 66% (MAP). Comparison of the responses after infusion with blood and dextran solutions indicated that hemodilution was an unlikely explanation for the attenuation of the reflex responses. Total arterial baroreceptor denervation (ABD) abolished the volume-related attenuation was still present following bilateral aortic nerve section or vagotomy. It thus appears that the carotid sinus responds to changes inblood volume and influences the reflex cardiovascular responses to afferent stimulation of the LAN. On the other hand, cardiopulmonary receptors subserved by vagal afferents do not appear to be involved.  (+info)

(5/19053) The effect of cardiac contraction on collateral resistance in the canine heart.

We determined whether the coronary collateral vessels develop an increased resistance to blood flow during systole as does the cognate vascular bed. Collateral resistance was estimated by measuring retrograde flow rate from a distal branch of the left anterior descending coronary artery while the main left coronary artery was perfused at a constant pressure. Retrograde flow rate was measured before and during vagal arrest. We found that in 10 dogs the prolonged diastole experienced when the heart was stopped caused no significant change in the retrograde flow rate, which indicated that systole has little effect on the collateral resistance. However, when left ventricular end-diastolic pressure was altered by changing afterload or contractility, a direct relationship between end-diastolic pressure and collateral resistance was noted.  (+info)

(6/19053) Effect of electrotonic potentials on pacemaker activity of canine Purkinje fibers in relation to parasystole.

Isolated false tendons excised form dog hearts were mounted in a three-chamber tissue bath. Isotonic sucrose solution was perfused in the central chamber to provide a region of depressed conductivity between the fiber segments in chambers 1 and 3, which were perfused with Tyrode's solution. The electrotonic influence of spontaneous or driven responses evoked in chamber 3 during the first half of the spontaneous cycle of a chamber 1 peacemaker delayed the next spontaneous discharge. This effect changed to acceleration when the chamber 3 segment fired during the second half of the spontaneous cycle. We found that subthreshold depolarizing current pulses 50-300 msec applied across the sucrose gap caused similar degrees of delay or acceleration. Furthermore, hyperpolarizing currents caused the reverse pattern. The results indicate that the discharge pattern of a parasystolic focus may be altered by the electrotonic influence of activity in the surrounding tissue. The significance of these findings is considered in relation to the mechanism of production of parasystolic rhythms.  (+info)

(7/19053) Evaluation of the force-frequency relationship as a descriptor of the inotropic state of canine left ventricular myocardium.

The short-term force-frequency characteristics of canine left ventricular myocardium were examined in both isolated and intact preparations by briefly pertubing the frequency of contraction with early extrasystoles. The maximum rate of rise of isometric tension (Fmas) of the isolated trabeculae carneae was potentiated by the introduction of extrasystoles. The ratio of Fmas of potentiated to control beats (force-frequency ratio) was not altered significantly by a change in muscle length. However, exposure of the trabeculae to isoproterenol (10(-7)M) significantly changed the force-frequency ratio obtained in response to a constant frequency perturbation. Similar experiments were performed on chronically instrumented conscious dogs. Left ventricular minor axis diameter was measured with implanted pulse-transit ultrasonic dimension transducers, and intracavitary pressure was measured with a high fidelity micromanometer. Atrial pacing was performed so that the end-diastolic diameters of the beats preceding and following the extrasystole could be made identical. Large increases in the maximum rate of rise of pressure (Pmas) were seen in the contraction after the extrasystole. The ratio of Pmax of the potentiated beat to that of the control beat was not changed by a 9% increase in the end-diastolic diameter, produced by saline infusion. Conversely, isoproterenol significantly altered this relationship in the same manner as in the isolated muscle. Thus, either in vitro or in situ, left ventricular myocardium exhibits large functional changes in response to brief perturbations in rate. The isoproterenol and length data indicate that the force-frequency ratio reflects frequency-dependent changes in the inotropic state, independent of changes in length.  (+info)

(8/19053) Developmental synaptic changes increase the range of integrative capabilities of an identified excitatory neocortical connection.

Excitatory synaptic transmission between pyramidal cells and fast-spiking (FS) interneurons of layer V of the motor cortex was investigated in acute slices by using paired recordings at 30 degrees C combined with morphological analysis. The presynaptic and postsynaptic properties at these identified central synapses were compared between 3- and 5-week-old rats. At these two postnatal developmental stages, unitary EPSCs were mediated by the activation of AMPA receptors with fast kinetics at a holding potential of -72 mV. The amplitude distribution analysis of the EPSCs indicates that, at both stages, pyramidal-FS connections consisted of multiple functional release sites. The apparent quantal size obtained by decreasing the external calcium ([Ca2+]e) varied from 11 to 29 pA near resting membrane potential. In young rats, pairs of presynaptic action potentials elicited unitary synaptic responses that displayed paired-pulse depression at all tested frequencies. In older animals, inputs from different pyramidal cells onto the same FS interneuron had different paired-pulse response characteristics and, at most of these connections, a switch from depression to facilitation occurred when decreasing the rate of presynaptic stimulation. The balance between facilitation and depression endows pyramidal-FS connections from 5-week-old animals with wide integrative capabilities and confers unique functional properties to each synapse.  (+info)