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Generation of the Action Potential
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In contrast to a voltage clamp, a current clamp is a method of intracellular recording involving measurement of the voltage difference across the cellular membrane while injecting a constant positive or negative current (as “square” d.c. pulses) into the cell. Current clamp is used to study the response of a neuron to an inward or outward electric current, which is important, for example, for understanding how the neuron responds to neurotransmitters that act by opening membrane ion channels.
Using the in vitro Hippocampal Slice as a Model to Teach Methods in Neurophysiology
Published in Avital Schurr, Benjamin M. Rigor, BRAIN SLICES in BASIC and CLINICAL RESEARCH, 2020
We found that sharp electrode, intracellular recording was not practical for our teaching laboratory. It required a significant degree of skill and was sensitive to variations in electrode configuration, micromanipulator drift, and small disturbances in mechanical stability. Thus, for studying the principles of intracellular recording, we developed a laboratory exercise using the “blind”, whole-cell patch-clamp technique.4 With this technique whole-cell recordings are relatively easy to achieve and to maintain (e.g., for an hour or more), the principles of “intracellular” recording can be studied equally as well as with sharp electrode recording, and there are the additional advantages of being able to rapidly alter the composition of the intracellular fluid and manipulate equilibrium potentials. We used a patch-clamp amplifier for this laboratory, although one can use a current-clamp amplifier if voltage clamping is not an objective of the exercise.
Distinct effects of resveratrol on seizures and hyperexcitability induced by NMDA and 4-aminopyridine
Published in Nutritional Neuroscience, 2019
Ya-Jean Wang, Chung-Pin Hsieh, Ming-Huan Chan, Tzu-Yi Chan, Linyi Chen, Hwei-Hisen Chen
Evoked action potential firing was performed by holding membrane potential at −65 mV and then depolarizing cell through a positive current injection (ranging from 5 to 30 pA). To record the action potentials, the chamber solutions were applied with normal Tyrode’s solution. The composition of normal Tyrode’s solution was as follows (in mM): NaCl 136.5, KCl 5.4, CaCl2 1.8, MgCl2 0.53, glucose 5.5, and HEPES 5.5 (pH 7.4). The patch pipettes solutions contained (mM): KCl 145, MgCl2 1, Na2ATP 3, EGTA 0.1, and HEPES 5.5 (pH 7.2). The frequency of action potentials was measured in 6 seconds current clamp. Then, the NMDA receptor-dependent action potentials were evoked by co-application of NMDA (100 μM) and glycine (100 μM). 4-AP (100 μM) was added into the chamber to trigger the 4-AP-mediated action potentials.
An update on the advancing high-throughput screening techniques for patch clamp-based ion channel screens: implications for drug discovery
Published in Expert Opinion on Drug Discovery, 2018
Alison Obergrussberger, Tom A. Goetze, Nina Brinkwirth, Nadine Becker, Søren Friis, Markus Rapedius, Claudia Haarmann, Ilka Rinke-Weiß, Sonja Stölzle-Feix, Andrea Brüggemann, Michael George, Niels Fertig
In conclusion, automated patch clamp systems have come a long way in recent years, both in terms of throughput and flexibility. Medium-throughput systems such as the Patchliner and QPatch have been appreciated on the market due to high quality data acquisition and flexible add-ons, for example, temperature control. However, with 8 or 16 recording channels, the resulting throughput of these systems does not address the needs of HTS laboratories. This changed in 2013/2014 with the launch of the SyncroPatch 384/768PE (Nanion Technologies) and Qube (Sophion Biosciences). Recording from up to 768 cells in parallel, the SyncroPatch 768PE is the highest throughput automated patch clamp system on the market with giga-ohm data quality. APC instruments such as the SyncroPatch 384/768PE offer high throughput, a low cost per data point and high data quality, and include many enabling features for advanced and sophisticated ion channel assays on a research grade level. Features such as temperature control have recently been added as optional add-ons as experimental procedures and standards, for example the CiPA initiative, demand it. Additional features such as optical stimulation, current clamp, and dynamic clamp are also being developed on automated patch clamp devices for drug discovery and cardiac safety applications.
Dieckol is a natural positive allosteric modulator of GABAA-benzodiazepine receptors and enhances inhibitory synaptic activity in cultured neurons
Published in Nutritional Neuroscience, 2021
Sangoh Kwon, Jong Hoon Jung, Suengmok Cho, Kwang-Deog Moon, Jaekwang Lee
Next, we recorded cultured cortical neurons to monitor neuronal membrane activity in current-clamp mode. Recorded neurons generated action potentials (APs) in Mg2+ free-HEPES solution. The firing rate of APs was reduced by DZP and restored following co-treatment with FLZ as similar with previous reports [25,26]. Dieckol showed the similar inhibitory effect on excitatory neural activity via GABAA-BDZ receptors (# of AP [%]; Before, 100 ± 8.97; Dieckol, 71.71 ± 8.58; Dieckol + FLZ, 94.74 ± 5.30, n = 5, P < 0.05, Figure 4B and C). These results confirmed that Dieckol has an inhibitory effect on neural networks to enhance the activity of GABAA-BZD receptors.