Patch-clamp amplifier

Electrophysiological Experiments. Guinea pig myocardial cells prepared as described previously 24) were superfused at 37 C with a Tyrode solution. Electrical properties of the myocytes were examined by the patch-clamp methods (25) using fire-polished pipettes. The current was measured by means of a patch-clamp amplifier, stored on the tape through a digital PCM data recording system, and analyzed with a computer. 

Figure 1 Schematic diagrams illustrating the patch-clamp technique. (A) Overall setup for isolating single ionic channels in an intact patch of cell membrane. P = patch pipet R = reference microelectrode I = intracellular microelectrode Vp = applied patch potential Em = membrane potential Vm = Em — Vp = potential across the patch A = patch-clamp amplifier. (From Ref. 90.) (B) Five different recording configurations, and procedures used to establish them, (i) Cell attached or intact patch (ii) open cell attached patch (iii) whole cell recording (iv) excised outside-out patch (v) excised inside-out patch. Key i = inside of the cell o = outside of the cell. (Adapted from Ref. 283.)...

A circuit that uses a differential amplifier to maintain constant membrane potential by electronically balancing the ion channel current. This method allows the experimenter to analyze action potentials of excitable membranes resulting from an initial transient rise in sodium ion permeability followed by a transient rise in potassium ion permeability The technique is especially valuable for studying kinetic properties of voltage-gated channels as well as voltage-dependent channels. See Membrane Potential Patch Clamp Methods... 

Figure 4. (a) Planar bilayer membrane system for single-channel currents measurement. Soybean lecithin in n-decane was applied to a hole separating two aqueous chambers. Chambers were filled with metal chloride salt at pH 7.2. The voltage was applied to the outer cell with respect to the inner. The currents across the bilayer were recorded on a PCM recorder through a patch-clamp amplifier and a lowpass filter, (b) Typical records of current observed at -t-50.0 mV (symmetrical 0.5 M solution). Currents increase upward from the zero level shown by the dotted line in each panel. 

Tel. +49 6151 56000 Fax +49 6151 56060 (electrophysiological equipment, pullers, patch clamp amplifiers)... 

Current clamp mode. In this mode the current is kept constant by the patch-clamp amplifier while voltage is measured, allowing recordings of the membrane potential. 

For patch clamp measurements, the PDMS planar electrode array was plasma oxidized and then motmted in the recording system shown in Fig. 6. To electrically isolate each electrode, the partition was sealed onto the chamber bottom over an array of openings that each contained an Ag-AgCl wire and suction tubing. The Ag-AgCl wire was connected to the multiplexer chip mounted on the circuit board under the chamber. The multiplexer then connected to the input of the amplifier. The tubing connected to a suction manifold that permitted individual or global suction. 

Electrophysiology Recordings To record currents from sealed cells, the silicon chip assembly was used as a chamber for a voltage clamp setup (Fig. 6). Each half of the chamber (top and bottom) was connected to the electrodes of a headstage. The top chamber was connected to the input of the patch clamp amplifier, and the bottom chamber was connected to either the ground or the command voltage depending on the amplifier used. 

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