No abstract available.
Cochlear Nucleus ; Patch-Clamp Techniques

Brain ; N-Methylaspartate ; Neurons ; Patch-Clamp Techniques

Action Potentials ; Brain ; Neurons ; Patch-Clamp Techniques

A USB bus based data interface technology for full auto Patch-Clamp system is discussed in the article. The main controller is CY2131QC (Cypress) and the logic controller is EPM3256A (Altera). Optocouplers are used to get rid of the noise from the interface. It makes the installation of the Patch-Clamp system easier by using the USB bus, and is suitable for the new generation of the Patch-Clamp system with a high speed of 1M bytes/s.
Computer-Aided Design ; Equipment Design ; Patch-Clamp Techniques ; instrumentation ; methods

In this paper we present an easily available method of intracellular dialysis via a microcatheter inserted into glass pipette during patch clamp experiment. An oblique hole through the glass pipette holder (above the lateral hole for cell-seal suction) is drilled, through which a microcatheter (O.D.=0.1 mm) made from the universal pipetter tip by hand-drawing passes and sticks out of the holder mouth in parallel with the Ag-AgCl electrode. With a syringe connected to the microcatheter, substitution of intracellular solution and intracellular dialysis of drugs can be achieved easily. Compared with repatch technique and intracellular solution substitution techniques used abroad, this method operates more easily and can produce more reliable results.
Dialysis ; instrumentation ; methods ; Equipment Design ; Microelectrodes ; Patch-Clamp Techniques ; instrumentation

OBJECTIVECurrents contributing repolarization in rabbit ventricular myocyte are very complex since the I(To.s) covers almost the whole repolarization phase of the action potential. The other components of repolarizing currents, as I(Kr) and I(Ks) are small. The purpose of this study is to investigate whether or not there are other currents in rabbit ventricular repolarization.

METHODSIon currents of rabbit ventricular myocyte were recorded using the whole-cell patch-clamp technique.

RESULTSIn the present work, an nonselective cation current was identified by replacing the K(+) with Cs(+) in the bathing and pipette solutions. The outward current elicited by depolarizing potentials could be inhibited by Gd(3+), an effective inhibitor of nonselective cation currents. Depleting Ca(2+) and Mg(2+) in the bathing solution, the amplitudes of this outward current increased by 40%-116% at +60 mV, and adding 2 micromol/L insulin to the solution (with normal concentration of Ca(2+) and Mg(2+) in Tyrode's solution), the amplitude increased by 30%-60% at +60 mV.

CONCLUSIONIt is suggested that a nonselective cation current in rabbit ventricular myocytes may play an important role in the repolarization of the action potential in rabbit ventricle. Changes of nonselective cation current will lead to induce or inhibit arrhythmia.

Animals ; Membrane Potentials ; Myocytes, Cardiac ; physiology ; Patch-Clamp Techniques ; Rabbits

Patch clamp is a technique that can measure weak current in the level of picoampere (pA). It has been widely used for cellular electrophysiological recording in fundamental medical researches, such as membrane potential and ion channel currents recording, etc. In order to obtain accurate measurement results, both the resistance and capacitance of the pipette are required to be compensated. Capacitance compensations are composed of slow and fast capacitance compensation. The slow compensation is determined by the lipid bilayer of cell membrane, and its magnitude usually ranges from a few picofarads (pF) to a few microfarads (μF), depending on the cell size. The fast capacitance is formed by the distributed capacitance of the glass pipette, wires and solution, mostly ranging in a few picofarads. After the pipette sucks the cells in the solution, the positions of the glass pipette and wire have been determined, and only taking once compensation for slow and fast capacitance will meet the recording requirements. However, when the study needs to deal with the temperature characteristics, it is still necessary to make a recognition on the temperature characteristic of the capacitance. We found that the time constant of fast capacitance discharge changed with increasing temperature of bath solution when we studied the photothermal effect on cell membrane by patch clamp. Based on this phenomenon, we proposed an equivalent circuit to calculate the temperature-dependent parameters. Experimental results showed that the fast capacitance increased in a positive rate of 0.04 pF/℃, while the pipette resistance decreased. The fine data analysis demonstrated that the temperature rises of bath solution determined the kinetics of the fast capacitance mainly by changing the inner solution resistance of the glass pipette. This result will provide a good reference for the fine temperature characteristic study related to cellular electrophysiology based on patch clamp technique.
Cell Membrane ; Electric Capacitance ; Membrane Potentials ; Patch-Clamp Techniques ; Temperature

The inferior colliculus (IC) is a pivot along the central auditory pathway. Using infrared visual whole-cell patch clamp recording technique, we investigated the electrophysiological properties of IC subnuclei neurons. Recordings were made from 88 neurons, including 21 neurons from the dorsal cortex of the IC (ICd), 43 neurons from the central nucleus of the IC (ICc) and 24 neurons from the external cortex of the IC (ICx). Based on the responses to positive current injection, three firing patterns, i.e., onset (6.8%, n = 6), adapting (39.8%, n = 35) and sustained (53.4%, n = 47) patterns, were identified. The hyperpolarization-activated inward current (Ih) could be recorded in half of the neurons (49/88). The sustained pattern occurred in more than half of ICd and ICc neurons (61.9% and 67.4%), while the adapting pattern occurred in majority of ICx neurons (75%). Action potential (AP) threshold and time constant also showed significant differences across neurons from the ICd, the ICc and the ICx. Our results indicate that IC neurons are different in electrophysiological properties across the subnuclei. The variance of the responses may be related to the distinct types of neurons as well as the received projections, which is implicated in the distinct roles of IC neurons in central auditory processing.
Action Potentials ; Animals ; Electrophysiological Phenomena ; In Vitro Techniques ; Inferior Colliculi ; cytology ; Mice ; Neurons ; cytology ; Patch-Clamp Techniques

OBJECTIVETo establishing the cochlea slice technique and infrared visual slice patch clamp method in order to observe the electrophysiological characteristics of rat spiral ganglion neurons (SGN) METHODS: SD rats were divided into three groups according to postnatal days old (0-2 d, 3-6 d and 7-14 d). Making slice of SD rat cochlear quickly, using infrared differential interference contrast (IR-DIC) technique, together with slice patch clamp, the electrophysiological characteristics of rat spiral ganglion neurons were observed, and factors which affected the quality of cochlear slice and recording of patch clamp were analyzed.

RESULTSThe success rate of 3-6 days SD was the highest, and 2-4 pieces of slice could be made from each cochlea. Cochlea connecting with partial skull and integrity of cochlear hull were the key for making slice, and the angle of modiolus axis should be adjusted to be parallel to the knife and the preparing time should be shorter. The SGN cell of good condition could be easily found and the seal test became easier with the help of infrared visual slice patch clamp method. The rest membrane potential was (-45.6 +/- 5.3) mV (x +/- s, n=52) and the current of Na+ and K+ could be activated.

CONCLUSIONSCochlear slice technique can retain structural integrity, cell viability and their association in cochlea, which suggest that this technique provides carrier for electrophysiological study of rat spiral ganglion neurons, and patch clamp with infrared videomicroscopy method can be used to make direct real-time observation in electrophysiological experiments of SGN, which can provide important technique support and reference for deep study of electrophysiological characteristics of SGN and auditory neurotransmission in cochlea.

Animals ; Cochlea ; physiology ; Microtomy ; Neurons ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; physiology

In the present study, we used in vitro whole-cell patch-clamp technique to record and analyze oscillatory activity of neurons in the optic tectum of Xenopus. Two patterns of subthreshold oscillations were induced by long-term depolarizing current pulses. One of the oscillating patterns occurred without a slow inward current (SIC); the other was superimposed on the SIC. The subthreshold oscillations were induced by depolarization in 48% of the recorded neurons. Both the oscillations and the SIC were tetrodotoxin (TTX)-resistant, but neither occurred when the slices were immersed in Ca(2+) free solutions. The evocation of the oscillations was voltage-sensitive: only when the initial membrane potentials of the neurons were held at -40 mV or -50 mV, 10 mV depolarization could induce the subthreshold oscillations. The amplitude and duration of the SIC depended on the level of the initial membrane potential. The subthreshold oscillations might play an important role in the physiological and behavioral functions of frogs, e.g. pattern discrimination, prey recognition, avoiding behavior etc., furthermore, these oscillations might play roles in the integration of neural activity in both mammals and non-mammalian vertebrates.
Animals ; Cell Polarity ; Membrane Potentials ; Neurons ; cytology ; Patch-Clamp Techniques ; Tetrodotoxin ; pharmacology ; Xenopus