Patch Clamp Technique Basic Concepts What is this poster about? Bioelectrical signals are transient pulsations propagated throughout the membrane of living cells such as muscular cells and neurons. Recording of bioelectrical signals is, thus, essential to understand how these signals are propagated and, ultimately, how communication is established through our entire body. This work shows how Biomedical Engineering, in association with Electrophysiology, may act in this area to create and develop new materials, instruments and techniques to help measuring bioelectric signals. Therefore, along with the basic anatomic and physiological concepts, we briefly present the bioelectrical transmission. How Do We Record the Signals? Future Prospectives Conclusion/Discussion The contribution of Biomedical Engineering Techniques on Bioelectrical Signal Recording have brought new ideas and solutions for the understanding of the mechanics involved on communication within our body. The knowledge of how we can control ions conduction and maybe interact with our neurons signals is directly related to the level of technological development, thus it is important to simulate and test the dynamics of neuron cells as a path to understand our own physiology and to improve people's health. Acknowledgements: Prof. Ana M. Sebastião and Raquel Dias, Departamento de Neurociências, FMUL I NTRODUÇÃO À E NGENHARIA B IOMÉDICA – 1 ST YEAR – 1 ST SEMESTER – MEB IOM - IST How Can We Clamp a Cell?  Keeps the electrical current constant;  Records the membrane potential by injecting current into a cell through a microelectrode.  Holds the membrane potential at a set level; Advantages: record individual channels; good pharmacology and the inside/outside solutions can be changed. Disadvantage: channel properties can be changed. The cell is impaled (a neuron, for e.g.) with a sharp glass electrode and the voltage (current-clamp) or the current (voltage- clamp) is recorded across the membrane. Intra-Corporal (Cell Surface) records Population of cells ECG EEG An Action Potential is a rapid alteration of the transmembrane voltage generated by the activity of voltage-gated ion channels embedded in the cell membranes. It can be divided into five phases: the resting potential (1), threshold, the rising phase (2), the falling phase (3) and the recovery phase (4). Only a few potassium channels are opened during resting phase. A few sodium channels open, bringing the potential past the threshold level. After the overshoot phase, many sodium channels begin to close and potassium channels begin to open. Activation of potassium channels reaches its maximum. It occurs at specialized junctions called synapses. The most common type of synapse is the chemical synapse: Basic structure and components of a synapse. The resulting depolarization, due to opening of voltage-gated sodium channels, initiates a sequence of events leading to the release of the transmitter. The Ca 2+ ions trigger the release of neurotransmitter by causing the synaptic vesicles to fuse with the presynaptic membrane. This fusion process is regulated by the interaction between protein complexes expressed on the vesicle and presynaptic membranes. Vesicles empty their content of neurotransmitter into the synaptic cleft. The neurotransmitter binds to receptors on the postsynaptic membrane; depolarization signal is thus propagated to the postsynaptic cell. MOURA, Guilherme, NUNES, Sandro, PORTEIRA, Ana lower background noise and increased signal bandwidth which allows a more reliable and precise recording; Superior Designs of Integrated nanoelectronic patch clamp amplifiers The implementation of more resistive nanomaterials in the construction of the coating or the pipette may facilitate the gigaseal formation and, thus, help isolate the patch being studied. Development of New Nanomaterials Recording techniques and, especially, patch clamp is highly dependant on nanotechnology. As such, future improvements in this area may help to develop precision and cost of this method: Voltage Clamp Current Clamp Intracellular Extracellular What is an Action Potential? How Synaptic Transmission is Processed? Extra-corporal (Skin Surface) Discovered by: Whole Cell Advantages: good pharmacology and high definition in the current recording. Disadvantage: dialysis of cytoplasmatic contents ´´´´´´´´´´´´´´´´´´´´´´´´´´ Perforated Patch Makes small holes on the patch with pore-forming agents such as antibiotics and other drugs, instead of applying suction TESTING Whole-cell RESULTS Amplitude and frequency changes over 40 min recording time Action potential recording from a pyramidal cell in a current clamp mode Clamped Cell Set-Up for the experiement Inside Out/ Outside Out Patch Clamp Modes: Hodgkin & Huxley, Nobel Prize Winners in 1963  Measures ion currents across a neuronal membrane. The different methods VS