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PubMed1992

Patch-clamp recordings of spiking and nonspiking interneurons from rabbit olfactory bulb slices: membrane properties and ionic currents.

Physiological and morphological properties of rabbit, Oryctolagus cuniculus, olfactory bulb interneurons were characterized by using a thin slice preparation in combination with patch-clamp measurements and Lucifer Yellow fills. Two types of interneurons, periglomerular (PG) and juxtaglomerular (JG) cells, were unequivocally distinguished in the glomerular layer. Their properties were compared to those of mitral cells. PG cells closely resembled previously described periglomerular cells in their morphology. During current clamp recording these neurons were characterized by their lack of action potentials upon depolarization. Consistent with these results no Na+ currents could be elicited in voltage clamp experiments. Two types of outward K+ currents were distinguished: one which inactivated and one which did not. From their morphology JG cells appear to be either short axon cells or external tufted cells. JG cells always responded with a single, TTX-blockable action potential in response to maintained current injection. Two types of membrane currents were identified in JG cells during voltage clamp: a fast, inactivating Na+ current that was fully activated at -80 mV, and a sustained outward current that shared some properties with a delayed rectifier K+ current. The particular relationship between the voltage dependence of the Na+ and K+ currents appeared to preclude repetitive spike activity.

Action Potentials↗

PubMed1990

The blockade of excitation/contraction coupling by nifedipine in patch-clamped rat skeletal muscle cells in culture.

The effects of the dihydropyridine derivative, nifedipine, well known as a blocker of calcium channels, were tested on cultured rat myoballs. Membrane currents and contractions were simultaneously recorded by means of the patch-clamp technique and a photoelectric transducing method. High concentrations of nifedipine (5 microM) inhibited the contractile responses and inward calcium current (ICa) elicited by long depolarizations. In the absence of ICa (1.5 mM cadmium in the bath), nifedipine inhibited both the ICa-independent contractile component and the outward current, supposed to depend on the intracellular calcium released during contraction. At low concentrations (0.5 microM) the blocking effects of nifedipine could be strongly enhanced by shifting the membrane potential towards less negative values (-60 mV) for 50 s prior to the test pulse. A blocking effect of nifedipine, at a usually ineffective concentration (0.1 microM), could also be observed when long-lasting (3 min) prepulses to 0 mV were applied from a reference membrane potential of -60 mV. This effect could be relieved by long-lasting cell hyperpolarizations (-90 mV). The blocking effects of nifedipine unrelated to ICa could be interpreted as an action on a molecule (voltage sensor) in the T-tubule membrane involved in the excitation/contraction coupling process and as a preferential binding of the dihydropyridine derivative on the inactivated form of this molecule, favored by the weak negative potentials or long-lasting depolarizations. The results provide data in favor of the existence of strong similarities between the calcium channels and voltage sensors since their operation was inhibited in a voltage-dependent manner by nifedipine.

Animals↗

PubMed1994

Ion Channels in the Xylem Parenchyma of Barley Roots (A Procedure to Isolate Protoplasts from This Tissue and a Patch-Clamp Exploration of Salt Passageways into Xylem Vessels.

To identify mechanisms for the simultaneous release of anions and cations into the xylem sap in roots, we investigated voltage-dependent ion conductances in the plasmalemma of xylem parenchyma cells. We applied the patch-clamp technique to protoplasts isolated from the xylem parenchyma by differential enzymic digestion of steles of barley roots (Hordeum vulgare L. cv Apex). In the whole-cell configuration, three types of cation-selective rectifiers could be identified: (a) one activated at membrane potentials above about -50 mV; (b) a second type of outward current appeared at membrane potentials above +20 to +40 mV; (c) below a membrane potential of approximately -110 mV, an inward rectifier could be distinguished. In addition, an anion-specific conductance manifested itself in single-channel activity in a voltage range extending from about -100 to +30 mV, with remarkably slow gating. In excised patches, K+ channels activated at hyperpolarization as well as at depolarization. We suggest that salt is released from the xylem parenchyma into the xylem apoplast by simultaneous flow of cations and anions through channels, following electrochemical gradients set up by the ion uptake processes in the cortex and, possibly, the release and reabsorption of ions on their way to the xylem.

Journal Article↗

PubMed1992

A patch-clamp study of GABA- and strychnine-sensitive glycine-activated currents in post-natal tissue-cultured hippocampal neurons.

GABA- and strychnine-sensitive glycine-activated currents in post-natal tissue-cultured hippocampal neurons were studied by using patch-clamp techniques. Current-voltage relations for both agonists in symmetrical Cl- solutions showed outward rectification. Strychnine-sensitive glycine-activated currents have not been studied in detail before in post-natal tissue-cultured hippocampal neurons. Partial desensitization of whole-cell currents was observed in symmetrical Cl- solutions during bath application of GABA- and glycine. In F-/Cl- solutions, both agonists gave a PF/Pcl value of about 0.06. The reversal potentials in mixtures of Cl- and SO4(2-) solutions were close to the equilibrium potentials of Cl- in the presence of both GABA and glycine. Single channels in inside-out excised patches with 2 mumol l-1 GABA and 5 mumol l-1 glycine in the pipette showed outward current rectification. The dose-response curves for GABA and glycine gave Kd values of 52 and 61 mumol l-1, respectively, and Hill coefficients close to 2. GABA and glycine binding were competitively blocked by their respective antagonists (bicuculline and strychnine). The similarities between GABA- and glycine-activated currents and the response in a combination of saturating concentrations of both GABA and glycine implied that the two agonists activated comparable numbers of anatomically distinct channels with very similar permeation properties.

Animals↗

PubMed1993

A patch clamp study of excitatory amino acid effects on cortical astrocyte subtypes in culture.

Electrophysiological effects of the excitatory amino acids (EAAs) glutamate (Glu) and kainate (KA) on membrane properties of confluent (> 7-9 day) astrocyte cultures were examined. The whole-cell patch clamp technique was employed to measure membrane currents. Cells were subdivided antigenically, morphologically and electrophysiologically into type-1-like and type-2 astrocytes. Lucifer yellow injection showed that type-1-like, but not type-2, astrocytes were electrically coupled in type-2 astrocytes, EAAs induced a cationic current by activating an ionotropic Glu receptor. The underlying receptor mechanism was KA-preferring and was blocked by the broad-spectrum EAA receptor channel antagonist kynurenate (Kyn). The current was dose-dependent and gave a Hill coefficient close to 2 for KA. In type-1-like astrocytes, EAA effects were agonist-dependent. Glu action involved an inward current mainly carried by an electrogenic Glu uptake system. This current was suppressed by the Glu uptake blocker DL-aspartate beta hydroxamate (ABH), but was not sensitive to Kyn. On the other hand, KA activated Kyn-sensitive receptors and was still able to induce this current in the presence of ABH. In type-1-like astrocytes, application of KA on average produced no conductance change. However, application of Ringer containing 5 mM Ba2+ caused a significant increase in input resistance and KA applied in the presence of Ba2+ consistently increased input conductance. In both subtypes of astrocyte, the KA-induced current was predominantly Na(+)-dependent, although in type-2 cells a small, Na(+)-independent current was also seen. These results support recent findings that type-1-like and type-2 astrocytes possess KA-preferring ionotropic receptors and type-1-like astrocytes also possess an electrogenic Glu uptake system.

Action Potentials↗

PubMed1988

Potassium Channels in Motor Cells of Samanea saman: A Patch-Clamp Study.

Leaflet movements in Samanea saman are driven by the shrinking and swelling of cells in opposing (extensor and flexor) regions of the motor organ (pulvinus). Changes in cell volume, in turn, depend upon large changes in motor cell content of K(+), Cl(-) and other ions. We performed patch-clamp experiments on extensor and flexor protoplasts, to determine whether their plasma membranes contain channels capable of carrying the large K(+) currents that flow during leaflet movement. Recordings in the "whole-cell" mode reveal depolarization-activated K(+) currents in extensor and flexor cells that increase slowly (t((1/2)) = ca. 2 seconds) and remain active for minutes. Recordings from excised patches reveal a single channel conductance of ca. 20 picosiemens in both cell types. The magnitude of the K(+) currents is adequate to account quantitatively for K(+) loss, previously measured in vivo during cell shrinkage. The K(+) channel blockers tetraethylammonium (5 millimolar) or quinine (1 millimolar) blocked channel opening and decreased light- and dark-promoted movements of excised leaflets. These results provide evidence for the role of potassium channels in leaflet movement.

Journal Article↗

PubMed1987

Patch clamp characterization of sodium channels expressed from rat brain cDNA.

Sodium currents, INa, were recorded from Xenopus laevis oocytes which had been injected with mRNA synthesized by in vitro transcription of the rat brain sodium channel II cDNA (Noda et al. 1986 a, b). Patch pipettes were used to apply depolarizing voltage steps and to record macroscopic sodium currents of between 50 and 750 pA from cell-attached patches of the oocyte membrane. With a combination of whole-cell and patch clamp recording, the properties of the implanted sodium channels could be studied in detail. They were analyzed according to the model of Hodgkin and Huxley (1952 a) assuming three activation gates. The activation of the sodium currents is characterized by an equilibrium potential of -29 mV and an apparent gating charge of 8.7 e0. At -64 mV half of the sodium currents were inactivated. From single-channel current recordings, an elementary sodium channel conductance of 19 pS and an average open time of 0.43 ms were obtained at -32 mV membrane potential and 16 degrees C. The single-channel and activation properties of rat brain sodium channel II are therefore comparable to those found in peripheral nerve and skeletal muscle, but inactivation occurs at less negative potentials. This could be a specific property of the brain sodium channels and may underlie the maintained inward sodium currents reported in brain neurones (French and Gage 1985).

Animals↗

PubMed1994

Distribution and functional properties of 5-HT3 receptors in the rat hippocampal dentate gyrus: a patch-clamp study.

1. In dentate gyrus of rat hippocampal slices two distinct types of neurons, principal excitatory neurons (granule cells) and local inhibitory neurons (basket cells), could be identified under Nomarski microscopy; I investigated the actions of serotonin using the whole-cell patch-clamp technique. The identification of the neurons was later confirmed by intracellular staining with Lucifer yellow. 2. In both basket cells and granule cells, whole-cell current recordings revealed spontaneous synaptic currents ranging from < 10 pA to > 200 pA in symmetrical Cl- conditions at a holding potential of -63 mV. These currents were blocked by 10 microM bicuculline, indicating that they resulted from the spontaneous activation of GABAergic inputs (which had been morphologically described in both types of neurons). 3. By focal application of serotonin (2-50 microM) to basket cells under current clamp I evoked a train of action potentials superimposed on a baseline membrane depolarization. Under voltage-clamp conditions serotonin evoked an inward current at a holding potential of -63 mV (currents were detectable in approximately 90% of basket cells studied). The inward current was accompanied by a multitude of small inward currents of short duration (< 100 ms) that were found to be due to the stimulation by serotonin of nearby GABAergic presynaptic neurons innervating the recorded neuron. 4. In granule cells (total of 11 cells) serotonin did not produce any responses under conditions similar to those used for basket cells. The occurrence of bicuculline-sensitive spontaneous synaptic current events seemed to increase during the application of serotonin; this phenomenon reflected the excitatory action of serotonin exclusively on GABAergic interneurons. 5. The serotonin-induced inward currents in basket cells were mediated by the 5-HT3 receptor subtype because 1) they were blocked by either metoclopramide (10 microM) or [3-alpha-tropanyl]-1H-indolecarboxylic acid ester (2 nM), the latter being a specific blocker for the 5-HT3 receptor subtype, and 2) almost similar currents were induced by the application of the selective 5-HT3 receptor agonist 2-methyl 5-HT (2-50 microM) or 1-(m-chlorophenyl)-biguanide (0.1-10 microM). 6. Current-voltage (I-V) relations of serotonin-induced currents in basket cells showed that the reversal potential was close to 0 mV in external standard saline and depended on the concentrations of monovalent cations. I-V relations of serotonin-induced currents revealed inward rectification at the membrane potential range of +30 to -60 mV.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

Patch-clamp analysis of voltage-gated currents in intermediate lobe cells from rat pituitary thin slices.

Ionic currents of hypophyseal intermediate lobe cells were studied using a thin-slice preparation of the rat pituitary in conjunction with conventional and perforated whole-cell patch-clamp recording techniques. A majority (89%) of the cells studied generated Na+, Ca2+ and K+ currents upon depolarizing voltage steps and responded to bath application of gamma-aminobutyric acid (GABA; 20-50 microM) with inward currents (in symmetrical chloride, holding potential -80 mV). A small percentage of cells (11%) did not display inward membrane currents upon depolarization and was unresponsive to GABA. In the first type of cells, Ca2+ and K+ currents were further studied in isolation. Ca2+ tail currents showed a biphasic time course upon repolarization, with time constants and amplitudes of 2.07 +/- 0.29 ms, 123 +/- 22 pA (for the slowly deactivating component) and 0.14 +/- 0.06 ms, 437 +/- 33 pA (for the fast-deactivating component; means +/- SD of n = 4 cells). Slowly and fast-deactivating conductances were half-maximally activated at around -10 mV and +10 mV respectively. Depolarizing voltage steps elicited two types of K+ current, which were separated using a prepulse protocol. A fast-activating, transient component showed half-maximal steady-state inactivation between -65 mV and -45 mV depending on the divalent cation composition of the external solution. Its decay was fitted by single-exponential functions with time constants of 36 +/- 11 ms and 3.9 +/- 0.9 ms at -20 mV and +40 mV respectively (mean +/- SD; n = 4 cells). Whereas the peak current amplitudes of the transient K+ current component remained stable, the amplitude of the second, delayed component increased progressively throughout the course of whole-cell experiments. In cells recorded with the perforated whole-cell technique, bath application of dopamine (10 nM-1 microM) induced large hyperpolarizations from a spontaneous membrane potential of -40 mV, but did not consistently affect the amplitude of the voltage-gated K+ conductances. These data are compared to previous studies using other preparations of the intermediate lobe, and differences are discussed, thus helping to extend our knowledge of electrical excitability of hypophyseal cells.

Animals↗

PubMed1986

A patch clamp study of the action of ethacyzine on the rapid inward sodium current in single rat heart muscle cells.

The effect of ethacyzine (a diethylamine analogue of ethmozine) on the rapid inward sodium current (INa) was studied in single rat ventricular muscle cells by a patch clamp technique. Extracellular application of 3 microM ethacyzine depressed the INa in a use-dependent fashion. Rest recovery from the use-dependent block by ethacyzine followed an exponential time course with a time constant of about 215 +/- 40 s (n = 4, mean +/- S.E.).

Animals↗

PubMed1992

Patch-clamp study of postnatal development of CA1 neurons in rat hippocampal slices: membrane excitability and K+ currents.

1. The postnatal development of membrane properties and outward K+ currents in CA1 neurons in rat hippocampal slices was studied with the use of whole-cell patch-clamp techniques. 2. Neurons at all postnatal ages (2-30 days; P2-30) were capable of generating tetrodotoxin (TTX)-sensitive action potentials in response to intracellular injection of depolarizing current pulses. There was a gradual increase in the amplitude and a decrease in the duration of these action potentials with age. Stable values for spike duration were reached by P15, whereas spike amplitude increased until P20-25. In P2-5 neurons, the duration of action potentials was greatly prolonged by depolarization from the resting membrane potential, indicating a weak spike repolarizing mechanism at depolarized potentials. In contrast, the duration of spikes evoked in P20-30 neurons was not affected by similar changes in the membrane potential. 3. Application of tetraethylammonium (TEA, 10 mM) had no effect on the duration of spikes in P3-5 neurons, whereas application of 4-aminopyridine (4-AP, 2 mM) produced large increases in spike duration. In contrast, the duration of spikes in P26 neurons was greatly increased after TEA application, whereas 4-AP had smaller effects on spike duration in these neurons. 4. The input resistance and membrane time constant decreased with age from P2 to P15. The values for both parameters were considerably greater than those reported with conventional intracellular recording electrodes in the immature hippocampus. The resting membrane potential became more hyperpolarized with age. When the recording pipettes contained KCl (140 mM), the resting potential of P3-4 neurons was 34 mV depolarized compared with resting potentials observed with potassium gluconate-filled pipettes. Only a 13-mV change in resting potential was observed during similar comparisons in P27-28 neurons. 5. Outward currents activated by depolarization were examined with the use of voltage-clamp techniques in P2-30 neurons. In P2-5 cells, a small, slowly inactivating outward current was evoked with depolarizing commands from holding potentials near -50 mV. By preceding the depolarizing commands with a hyperpolarizing prepulse, an additional early transient outward current was evoked. The sustained and transient outward currents were separated by their kinetic properties and their sensitivity to cobalt (Co2+), TEA, and 4-AP.(ABSTRACT TRUNCATED AT 400 WORDS)

4-Aminopyridine↗

PubMed1984

Patch-clamp studies of chloride channels activated by gamma-aminobutyric acid in cultured hippocampal neurones of the rat.

The properties of the GABA-activated ion channel in hippocampal neurones prepared from 17- to 19-day-old fetal rats in dispersed cell cultures were studied with the patch-clamp techniques. These neurones had chemosensitivity to gamma-aminobutyric acid (GABA) in the absence of synaptic inputs. GABA activated chloride ion channels selectively in these neurones. The GABA-induced Cl- current was detectable with greater than 1 microM GABA. The amplitude of the current increased with higher concentrations of GABA and apparently saturated at 100 microM. The effective single-channel conductance (gamma) was estimated to be 19 pS from the mean and variance of the steady-state GABA-induced current fluctuation in the whole-cell recordings. The power density spectra for GABA-induced current fluctuations in the whole-cell as well as cell-free outside-out membrane patch recordings had more than a single Lorentzian component. The application of GABA induced discrete pulse-like current flows through the cell-free outside-out membrane patch, after the number of channels activated by GABA had decreased due to the rundown. The single-channel conductance estimated from the amplitude of the current pulse was 29 pS when the intra- and extracellular Cl- concentrations were 150 and 120 mM, respectively. In addition to the above conducting state, the GABA channel had several open states with lower conductances. The apparent discrepancy between the effective single-channel conductance estimated from noise analysis and the single-channel conductances directly measured with individual channels may be due, at least in part, to the presence of multiple conducting states.

Animals↗

PubMed1992

A patch clamp study of the nicotinic acetylcholine receptor of bovine adrenomedullary chromaffin cells in culture.

1. Acetylcholine-induced currents recorded from bovine adrenal medullary chromaffin cells maintained in culture were studied during pressure or ionophoretic applications of ACh, using the 'whole-cell' and 'outside-out' configurations of the patch clamp technique. In standard salines, ACh evoked whole-cell currents of -38 pA to -1 nA at -60 mV, which had a reversal potential (EACh) of -7.1 +/- 0.6 mV. The ACh current-voltage relationship was characteristically linear at negative holding potentials and biphasic at positive holding potentials, displaying a region of almost zero slope conductance between 0 and +40 mV followed by a region of positive slope conductance at more positive potentials. 2. Relative permeation to cations was examined. Substitution of external Na+ by sucrose resulted in a -42 mV shift of EACh for a 10-fold reduction in [Na+]o. Using isotonic substitutions, the permeability ratios (relative to Na+) for monovalent cations were determined to be 1.32 +/- 0.02 for Cs+ (n = 11), 1.03 +/- 0.02 for Li+ (n = 8) and 0.18 +/- 0.02 for Tris+ (n = 7). Elevated external Ca2+ salines were found to shift EACh to more positive potentials, especially in the presence of low external Na+. 3. The nicotinic agonists nicotine, tetramethylammonium and lobeline evoked inward currents in bovine chromaffin cells. In contrast, decamethonium and the muscarinic agonist, methacholine, had no effect. 4. The nicotinic antagonists mecamylamine, trimetaphan, (+)-tubocurarine and hexamethonium caused dose-dependent reductions in the amplitude of ACh-evoked inward currents. The estimated IC50's were 0.25, 0.33, 0.63 and 2.2 microM respectively, for cells voltage clamped at -60 mV. High concentrations (> 2 microM) of the muscarinic antagonist, atropine, also produced a dose-dependent reduction in the amplitude of ACh-induced currents. 5. Inhibition by trimetaphan was voltage independent. With the other drugs the antagonism was voltage sensitive, increasing with membrane hyperpolarization. The voltage sensitivity was most marked for hexamethonium. Neither hexamethonium nor mecamylamine were found to depress ACh-evoked outward currents at concentrations which severely depressed inward currents. In addition to its antagonist actions, (+)-tubocurarine activated unitary currents in these cells and on isolated membrane patches. 6. The results indicate that nicotinic ion channels of bovine chromaffin cells have a similar ionic selectivity to monovalent cations, but that Ca2+ ions permeate the channels to a greater degree than at the motor endplate. The ACh current-voltage relationship resembles that described for other types of 'neuronal' nicotinic receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗

PubMed1990

Dissociation and culture of mechanosensory neurons for patch clamp analysis.

Single mechanosensory neurons were isolated from chordotonal organs of adult cockroach antennae. Transmission and scanning electron microscopy showed that the soma and part of the mechanosensory ending survived the dissociation. In culture, outgrowth occurred from the ending. Regions of cell membrane were accessible for patch clamp analysis and channels were recorded. The ability to record channel activity in isolated mechanosensory neurons will allow the study of mechanotransduction mechanisms at the membrane level.

Animals↗

PubMed1992

Effects of bradykinin on ion conductances in NG108-15 neuroblastoma x glioma hybrid cells recorded with patch-clamp electrodes.

Under whole-cell recording, bradykinin (BK) produced an initial outward membrane current followed by an inward current in voltage-clamped NG108-15 cells. The initial outward current was associated with a rise in intracellular Ca2+ and was accompanied by the opening of Ca(2+)-dependent K(+)-channels recorded with a cell-attached patch electrode. This current was inhibited by intracellular Mg2+. The inward current was associated with inhibition of the voltage-dependent K(+)-current IK(M). These effects accord with those previously observed in microelectrode-impaled cells, with the difference that BK produced much more pronounced and long-lasting desensitization in the patch-clamped cells.

Acetylcholine↗

PubMed1990

Patch clamp studies on root cell vacuoles of a salt-tolerant and a salt-sensitive plantago species : regulation of channel activity by salt stress.

Plantago media L. and Plantago maritima L. differ in their strategy toward salt stress, a major difference being the uptake and distribution of ions. Patch clamp techniques were applied to root cell vacuoles to study the tonoplast channel characteristics. In both species the major channel found was a 60 to 70 picosiemens channel with a low ion selectivity. The conductance of this channel for Na(+) was the same as for K(+), P(K) (+)/P(Na) (+) = 1, whereas the cation/anion selectivity (P(K) (+)/P(c1) (-)) was about 5. Gating characteristics were voltage and calcium dependent. An additional smaller channel of 25 picosiemens was present in P. maritima. In the whole vacuole configuration, the summation of the single channel currents resulted in slowly activated inward currents (t((1/2)) = 1.2 second). Inwardly directed, ATP-dependent currents could be measured against a DeltapH gradient of 1.5 units over the tonoplast. This observation strongly indicated the physiological intactness of the used vacuoles. The open probability of the tonoplast channels dramatically decreased when plants were grown on NaCl, although single channel conductance and selectivity were not altered.

Journal Article↗

PubMed1990

Patch clamp analysis of excitatory synapses in mammalian spinal cord slices.

Excitatory synaptic transmission to visually identified alpha-moto neurones was studied in thin slice preparations of the neonatal rat spinal cord. Excitatory postsynaptic currents (EPSCs) elicited by stimulation of intraspinal presynaptic fibres were recorded using the whole-cell patch clamp technique, following blockade of inhibitory transmission by bath application of strychnine and bicuculline. The EPSCs could be separated pharmacologically into N-methyl-D-aspartate- (NMDA) and non-NMDA-receptor-mediated components, where the contribution of the NMDA-mediated component was significant only at holding potentials more positive than -50 mV. Graded stimulation of intraspinal fibres showed that the NMDA- and the non-NMDA-mediated EPSCs were evoked by activation of presynaptic fibres with similar sensitivities to the stimulation intensity, suggesting that the same presynaptic fibres released the excitatory amino-acid (EAA) activating the two sub-sets of receptors. Studies of the amplitude fluctuations of EPSCs elicited by stimulation of a presumed single fibre revealed similar proportions of transmission failures and similar distributions of both the NMDA- and the non-NMDA-mediated components. These similarities suggest that the EAA transmitter activating the two sub-types of receptors is released from the same set of synaptic boutons and that the receptors are therefore post-synaptically co-localized. In addition the gamma aminobutyric acidB (GABAB) receptor agonist L-baclofen, which is known to decrease transmitter release, changed the amplitude distributions of non-NMDA- and NMDA-receptor-mediated EPSCs into unimodal distributions without affecting the amplitude of the presumed unitary event. The similarity between the transmitter release profiles of the two EAA components further supports the notion of postsynaptic receptor co-localization.

Animals↗

PubMed1987

A low-cost voltage stepper device for use in patch-clamp experiments.

A simple and inexpensive device is described which generates voltage steps or cycles of steps of defined amplitude and duration either automatically (triggered by internal or computer clock pulses) or on manual command. The device facilitates the investigation of the voltage dependence of ion channel currents in patch-clamp experiments.

Animals↗