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At least 199 records · Page 11Linked to original sources

PubMed1996

Whole-cell patch-clamp recording reveals subthreshold sound-evoked postsynaptic currents in the inferior colliculus of awake bats.

The inferior colliculus receives excitatory and inhibitory input from parallel auditory pathways that differ in discharge patterns, latencies, and binaural properties. Processing in the inferior colliculus may depend on the temporal sequence in which excitatory and inhibitory synaptic inputs are activated and on the resulting balance between excitation and inhibition. To explore this issue at the cellular level, we used the novel approach of whole-cell patch-clamp recording in the midbrain of awake bats (Eptesicus fuscus) to record EPSCs or IPSCs. Sound-evoked EPSCs were recorded in most neurons. These EPSCs were frequently preceded by an IPSC, followed by an IPSC, or both. These findings help explain the large latency range and transient responses that characterize inferior colliculus neurons. The EPSC was sometimes followed by long-lasting oscillatory currents, suggesting that a single brief sound sets up a pattern of altered excitability that persists far beyond the duration of the initial sound. In three binaural neurons, ipsilateral sound evoked a large IPSC that partially or totally canceled the EPSC evoked by contralateral sound. In one binaural neuron with ipsilaterally evoked IPSCs, contralaterally evoked IPSCs occurred in response to frequencies above and below the neuron's best frequency. Thus, both monaural and binaural interactions can occur at single inferior colliculus neurons. These results show that whole-cell patch-clamp recording offers a powerful means of understanding how subthreshold processes determine the responses of auditory neurons.

Acoustic Stimulation↗

PubMed2002

Patch-clamp experiments under micro-gravity.

For human based space research it is of high importance to understand the influence of gravity on the properties of single ion channels in biological membranes, as these are involved in about all biological processes. The patch clamp technique is the best established method to investigate electrophysiological properties of single ion channels in detail. Consequently, a patch clamp set-up was designed for the drop tower in Bremen, Germany. Using this set-up among others, successfully leech neurons have been patched under micro-gravity, delivering data about ion channel behaviour, which were compared to results from bilayer experiments in the drop tower and to results from lab controls under 1 g and under higher gravity.

Journal Article↗

PubMed2004

Detecting rearrangements of shaker and NaChBac in real-time with fluorescence spectroscopy in patch-clamped mammalian cells.

Time-resolved fluorescence detection of site-directed probes is a major tool in the investigation of structure-function relationships of voltage-dependent ion channels. However, the technique has been limited so far to the Xenopus-oocyte system making it difficult to study proteins, like, e.g., the prokaryotic sodium channel NaChBac, whose expression in oocytes is insufficient or whose physiological functions are distorted in oocytes. To expand the application of site-directed fluorescence detection to these proteins, we used two techniques-semiconfocal epifluorescence and total internal reflection fluorescence-to detect time-resolved fluorescence changes from site-directed labeled proteins expressed in mammalian cells under patch-clamp conditions, and investigated the characteristics and limitations of the techniques. The voltage-sensitive dye, di-8-ANEPPS, was used to monitor control of the membrane voltage in epifluorescence and total internal reflection fluorescence. Fluorescence changes in patch-clamped cells were recorded from a Shaker channel mutant (M356C) labeled in the S3-S4 linker using semiconfocal epifluorescence. The gating kinetics and fluorescence changes were in accordance with previous studies using fluorescence spectroscopy in Xenopus-oocyte systems. We applied our technique to the prokaryotic sodium channel NaChBac. Voltage-dependent protein-rearrangements of S4 could be detected that are independent of inactivation. Comparison of the S3-S4 linker regions revealed structural differences to the KvAP voltage sensor. The results from the NaChBac channel point to structural requirements for the S3-S4 loop to generate a fluorescence signal.

Amino Acid Sequence↗

PubMed1997

Analysis of multichannel patch clamp recordings by hidden Markov models.

Conventional methods of analysis do not allow the kinetics of patch clamped ion channels to be completely determined if more than one channel is present in the patch. This hinders investigations on small ion channels as well as on channel cooperativity and the homogeneity of channel populations. We present a method to extract the rate constants and current amplitudes for each individual channel from multichannel patches by a one-step procedure. For this purpose, the current record is modeled by the superposed Markov processes of the opening and closing of each channel that is contaminated by noise (Hidden Markov Model). Channel parameters are obtained by maximum likelihood methods. Because the parameters can be calculated directly from the unfiltered record, the dwell time and missed event problems are widely diminished. Confidence bounds for the estimated parameters are given. Statistical tests to decide whether channels switch identically and/or independently are introduced. The application of the method is demonstrated with simulated data.

Biometry↗

PubMed1995

Ca2+ ion transport through patch-clamped cells exposed to magnetic fields.

The total current of Ca2+ ions through patch-clamped cell membranes was measured while exposing clonal insulin-producing beta-cells (RINm5F) to a combination of DC and AC magnetic fields at so-called cyclotron resonance conditions. Previous experimental evidence supports the theory that a resonant interaction between magnetic fields and organisms can exist. This experiment was designed to test one possible site of interaction: channels in the cell membrane. The transport of Ca2+ ions through the protein channels of the plasma membrane did not show any resonant behavior in the frequency range studied.

Adenoma, Islet Cell↗

PubMed1988

Ca2+ not cyclic AMP mediates the fluid secretory response to isoproterenol in the rat mandibular salivary gland: whole-cell patch-clamp studies.

We have performed whole-cell patch-clamp studies on dispersed secretory cells of the rat mandibular gland to determine how beta-adrenergic stimulation causes fluid secretion. When the pipette contained a high K+ solution, the resting membrane potential averaged -33 mV +/- 1.1 (SEM, n = 34) and the clamped cell showed strong outward rectification. We monitored K+ and Cl- currents for periods of 15 min by recording the currents needed to clamp the cell potential at 0 and -80 mV, respectively. Isoproterenol (1-2 mumol/l) caused increases in the clamp current at 0 mV (the K+ current) and at -80 mV (the Cl- current) in about 80% of cases, although the responses were variable in size and time-course; the responses were indistinguishable from those induced by acetylcholine or the Ca2+ ionophore, A23187. The alpha-adrenergic antagonist, phentolamine (1-2 mumol/l), had no effect on the response, but the beta-adrenergic antagonist, propranolol (10 mumol/l), blocked it completely. The isoproterenol response could not be mimicked by application to either surface of the cell membrane, of cyclic AMP (100 mumol/l), forskolin (1 or 20 mumol/l) or cholera toxin (2.5 micrograms/ml). However, increasing the Ca2+-chelating capacity of the pipette solution by raising its EGTA concentration from the customary 0.5 to 20 mmol/l, blocked the response to isoproterenol, suggesting that beta-adrenergic agonists activate Cl- and K+ channels by raising cytosolic Ca2+. Since neomycin, which blocks phospholipase C, blocked the action of isoproterenol without impairing the cell responsiveness to A23187, it appears that isoproterenol, like muscarinic agonists, increased cytosolic Ca2+ via the phosphatidylinositol cycle.

Acetylcholine↗

PubMed2005

Induction of pancreatic duct cells of neonatal rats into insulin-producing cells with fetal bovine serum: a natural protocol and its use for patch clamp experiments.

AIM: To induce the pancreatic duct cells into endocrine cells with a new natural protocol for electrophysiological study. METHODS: The pancreatic duct cells of neonatal rats were isolated, cultured and induced into endocrine cells with 15% fetal bovine serum for a period of 20 d. During this period, insulin secretion, MTT value, and morphological change of neonatal and adult pancreatic islet cells were comparatively investigated. Pancreatic beta-cells were identified by morphological and electrophysiological characteristics, while ATP sensitive potassium channels (K(ATP)), voltage-dependent potassium channels (K(V)), and voltage-dependent calcium channels (K(CA)) in beta-cells were identified by patch clamp technique. RESULTS: After incubation with fetal bovine serum, the neonatal duct cells budded out, changed from duct-like cells into islet clusters. In the first 4 d, MTT value and insulin secretion increased slowly (MTT value from 0.024+/-0.003 to 0.028+/-0.003, insulin secretion from 2.6+/-0.6 to 3.1+/-0.8 mIU/L). Then MTT value and insulin secretion increased quickly from d 5 to d 10 (MTT value from 0.028+/-0.003 to 0.052+/-0.008, insulin secretion from 3.1+/-0.8 to 18.3+/-2.6 mIU/L), then reached high plateau (MTT value >0.052+/-0.008, insulin secretion >18.3+/-2.6 mIU/L). In contrast, for the isolated adult pancreatic islet cells, both insulin release and MTT value were stable in the first 4 d (MTT value from 0.029+/-0.01 to 0.031+/-0.011, insulin secretion from 13.9+/-3.1 to 14.3+/-3.3 mIU/L), but afterwards they reduced gradually (MTT value <0.031+/-0.011, insulin secretion <8.2+/-1.5 mIU/L), and the pancreatic islet cells became dispersed, broken or atrophied correspondingly. The differentiated neonatal cells were identified as pancreatic islet cells by dithizone staining method, and pancreatic beta-cells were further identified by both morphological features and electrophysiological characteristics, i.e. the existence of recording currents from K(ATP), K(V), and K(CA). CONCLUSION: Islet cells differentiated from neonatal pancreatic duct cells with the new natural protocol are more advantageous in performing patch clamp study over the isolated adult pancreatic islet cells.

Animals↗

PubMed2003

Loose-patch clamp currents from the hypothalamo-neurohypophysial system of the rat.

The loose-patch clamp technique was used to study voltage-activated currents from the surface of rat neurohypophysial and hypothalamic regions in situ. In the neurohypophysis, depolarizing pulses of 4-8 ms duration yielded tetrodotoxin (TTX)-sensitive sodium currents, a 4-AP-sensitive "A"-type potassium current, and a long-lasting outward TEA- and tetrandrine-sensitive Ca(2+)-activated potassium current. All of these currents were elicited during the application of the pulse. With high external calcium there were long-lasting inward currents blocked by Ni(2+) and Cd(2+), identifying them as voltage-gated calcium currents. Depolarizing pulses of 0.3-0.7 ms duration yielded fast biphasic responses, of 1-3 ms duration, composed of mostly sodium and "A"-type potassium currents. With high external calcium there were fast inward currents blocked by Ni(2+) and Cd(2+), indicating that these were voltage-gated calcium currents. These responses have the characteristics of action potential currents: they were elicited after the cessation of the applied pulse and the "A" component is eliminated together with the sodium component upon application of TTX. Similar responses to long and short pulses were obtained from the surface of the associated magnocellular somata in the supraoptic nucleus, and their projections. The explant currents are similar to those previously characterized using conventional methods from somata and terminals.

Animals↗

PubMed1995

Mixture suppression without inhibition for binary mixtures from whole cell patch clamp studies of in situ olfactory receptor neurons of the spiny lobster.

Whole cell patch clamping was used to investigate mechanisms of mixture suppression for in situ olfactory receptor neurons (ORNs) of the spiny lobster Panulirus argus. We used a set of single compounds and binary mixtures that have been used in previous biochemical studies of receptor-odorant binding, electrophysiological studies of spiking output from ORNs, and behavioral studies. These odorants were adenosine 5'-monophosphate (AMP), betaine (Bet), L-cysteine (Cys), L-glutamate (Glu), taurine (Tau), ammonium chloride, D,L-succinate, binary mixtures of these compounds, as well as a 33-component artificial oyster mixture (AOM). For the 40 ORNs studied, these stimuli more frequently elicited inward than outward currents. AMP, Glu, Tau and Bet evoked the largest and most numerous inward currents; Cys most commonly evoked outward currents. Na+ was an important charge-carrying ion for the Glu-evoked response in one ORN and the Bet-evoked response in another ORN. Mixture suppression, defined conservatively in this study as cases where the response to a binary mixture was less than the response to the more excitatory component of that mixture, was observed in 6 ORNs. In all 6 cases, neither component of the mixture evoked an outward conductance (i.e. neither was inhibitory). Five of these cases of mixture suppression involved a mixture containing two excitatory compounds (i.e. producing inward conductances): four ORNs were excited by both Glu and AMP, and one ORN was excited by both Tau and Glu. One case of mixture suppression occurred for a compound (Tau) tha did not produce a current when presented alone but which when added to Bet suppressed the inward current generated by Bet. Mechanisms for these suppressions are discussed, including inhibition of receptor binding by the components of a binary mixture and effects on second messengers or ion channels.

Adenosine Monophosphate↗

PubMed2000

Patch-clamp characterisation of somatostatin-secreting -cells in intact mouse pancreatic islets.

The perforated patch whole-cell configuration of the patch-clamp technique was applied to superficial cells in intact mouse pancreatic islets. Three types of electrical activity were observed corresponding to alpha-, beta- and delta-cells. The delta-cells were electrically active in the presence of glucose but lacked the oscillatory pattern seen in the beta-cells. By contrast, the alpha-cells were electrically silent at high glucose concentrations but action potentials could be elicited by removal of the sugar. Both alpha- and beta-cells contained transient voltage-activated K+ currents. In the delta-cells, the K+ currents activated above -20 mV and were completely blocked by TEA (20 mM). The alpha-cells differed from the delta-cells in possessing a TEA-resistant K+ current activating already at -40 mV. Immunocytochemistry revealed the presence of Kv3.4 channels in delta-cells and TEA-resistant Kv4.3 channels in alpha-cells. Thus the presence of a transient TEA-resistant current can be used to functionally separate the delta- and alpha-cells. A TTX-sensitive Na+ current developed in delta-cells during depolarisations beyond -30 mV and reached a peak amplitude of 350 pA. Steady-state inactivation of this current was half-maximal at -28 mV. The delta-cells were also equipped with a sustained Ca2+ current that activated above -30 mV and reached a peak of 60 pA when measured at 2.6 mM extracellular Ca2+. A tolbutamide-sensitive KATP channel conductance was observed in delta-cells exposed to glucose-free medium. Addition of tolbutamide (0.1 mM) depolarised the delta-cell and evoked electrical activity. We propose that the KATP channels in delta-cells serve the same function as in the beta-cell and couple an elevation of the blood glucose concentration to stimulation of hormone release.

Adenosine Triphosphate↗

PubMed1997

Anxiolytic activity of glycine-B antagonists and partial agonists--no relation to intrinsic activity in the patch clamp.

On the basis of animal models, anxiety was one of the first suggested clinical applications of partial agonists of the glycineB site coupled to the NMDA receptor. It is not certain, however, whether these findings can be extended to full glycineB antagonists and what is the relation between intrinsic activity (degree of NMDA receptor antagonism) and anxiolytic effect. In the present study several NMDA receptor antagonists, including several glycineB antagonists/partial agonists, were tested for anxiolytic activity in the Vogel conflict test and the elevated plus-maze. Additionally, the intrinsic activities of the glycineB partial agonists used [ACPC, (R,+)-HA-966 and D-cycloserine] were compared in patch-clamp experiments in cultured neurones. In the plus-maze the most striking increase in the time spent in open arms (index of anxiolytic effect) was seen after diazepam and D-cycloserine (at doses that did not change locomotion). Also reliable (dose-dependent), although weaker, anxiolytic activity was produced by the uncompetitive NMDA receptor antagonist (+)MK-801 and the competitive antagonist CGP 39551. Modest anxiolytic-like effect in the plus-maze was also observed after the glycineB antagonist L-701,324 and the partial agonist (+,R)-HA-966. Uncompetitive antagonists memantine and amantadine, the glycineB partial agonist ACPC (up to 600 mg/kg) or the full antagonists MRZ 2/570, MRZ 2/571 and MRZ 2/576 had no effect. In the Vogel conflict test neither memantine, nor any of the full glycineB antagonists tested (L-701,324 and MRZ 2/576), showed anxiolytic activity. Patch-clamp studies revealed that the intrinsic activity of (+,R)-HA-966, D-cycloserine and ACPC was 13, 57 and 92%, respectively, as compared to that of glycine itself (100%). In conclusion, for the agents tested there is no clear relation between the levels of intrinsic activity, i.e. degree of NMDA receptor inhibition, and anxiolytic activity. Moreover, L-701,324 and MRZ-type glycineB full antagonists do not exchibit anxiolytic activity in the elevated plus-maze and Vogel conflict test.

Animals↗

PubMed1992

Swelling-induced chloride-sensitive current in canine atrial cells revealed by whole-cell patch-clamp method.

An isoproterenol-induced chloride current has been detected in ventricular myocytes from guinea pig and rabbit but has not been found in canine ventricular cells. This investigation was undertaken to determine whether canine atrial cells possessed such a current. Steady-state currents were examined with potassium currents blocked by cesium. In whole-cell patch-clamp experiments, an isoproterenol-induced chloride current could not be detected shortly after patch rupture. However, whole-cell current in the absence of isoproterenol increased over time after patch rupture. The spontaneously activating steady-state current was outwardly rectifying with a reversal potential of approximately -25 mV. The current that developed over time was sensitive to variation in extracellular chloride concentration and was partially blocked by anthracene-9-carboxylic acid. Isoproterenol could enhance the amplitude of this current once it developed. Although isosmotic pipette filling and extracellular solutions were used, cell swelling was found to be the cause of the increase in whole-cell conductance that was observed during whole-cell patch-clamp experiments. The development of the current and the associated cell swelling could be prevented with the addition of 50-75 mM mannitol to the extracellular solution. The current could be observed in perforated patch recordings with nystatin when extracellular osmolarity was low (221 mosm/kg) but not when the extracellular solution was isosmotic (293 mosm/kg). Cardiac chloride currents have the potential to depolarize the resting membrane potential and cause abnormal automaticity. Chloride currents can also decrease the refractory period through a reduction in action potential duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Patch-clamp studies on epithelial sodium channels in salivary duct cells.

Mouse mandibular salivary duct cells contain an amiloride-sensitive Na+ current and express all three subunits of the epithelial Na+ channel, ENaC. This amiloride-sensitive Na+ current is subject to feedback regulation by intracellular Na+ and we have previously demonstrated that this regulation is mediated by an ubiquitin-protein ligase, which we identified as Nedd4. The evidence supporting this identification is as follows: (1) antibodies raised against murine Nedd4 block Na+ feedback inhibition; (2) a mutant of murine Nedd4 containing the WW domains but no HECT domain (ubiquitin-protein ligase) blocks Na+ feedback inhibition; and (3) Nedd4 is expressed in mouse mandibular salivary duct cells. In the present studies, we have used whole-cell patch-clamp methods to further investigate the mechanisms by which ubiquitin-protein ligases regulate the amiloride-sensitive Na+ conductance in mouse salivary duct cells. In particular, we have examined the possibility that the ubiquitin-protein ligase, KIAA0439, which is closely related to Nedd4, may mediate Na+ feedback control of amiloride-sensitive Na+ channels. Furthermore, we have attempted to define the mechanism by which ubiquitin-protein ligases inhibit Na+ channels. We have found that KIAA0439 is expressed in mouse mandibular ducts and interacts with the PY motifs of the alpha-, beta-, and gamma-subunits of ENaC in vitro. Furthermore, in whole-cell patch-clamp studies, a glutathione-S-transferase (GST)-fusion protein containing the WW motifs of human KIAA0439 was able to inhibit feedback regulation of the amiloride-sensitive Na+ current by intracellular Na+. We also examined whether GST-fusion proteins containing the C-termini of the alpha-, beta-, and gamma-subunits of ENaC are able to interrupt Na+ feedback regulation of the amiloride-sensitive Na+ current. We found that the C-termini of the beta- and gamma-subunits were able to do so, whereas the C-terminus of the alpha-subunit was not. We conclude that KIAA0439 is, together with Nedd4, a potential mediator of the control of epithelial Na+ channels in salivary duct cells by intracellular Na+. We further conclude that ubiquitin-protein ligases interact with the Na+ channels through the C-termini of the beta- and gamma-subunits of the Na+ channels.

Amiloride↗

PubMed1986

Some limitations of the cell-attached patch clamp technique: a two-electrode analysis.

With two independent patch electrodes sealed to small clusters of electrically coupled chick embryo cardiac cells, we have measured four parameters: true seal and patch resistance, channel conductance, and membrane potential. One electrode was in the cell-attached mode, and recorded current flowing in parallel through the membrane patch and seal. The second electrode, sealed on a different cell in the cluster, was in the whole cell recording configuration, and served to record or control the membrane potential of the cluster. We fit the four measured parameters to a simple electrical model to reveal errors not usually recognized in the patch-clamp technique. Among these are the following: (1) The apparent seal resistance, determined by changing the potential in a patch electrode, may be a poor estimate of true seal resistance, since it includes the parallel combination of seal- and patch-resistance. (2) Patch resistance may be influenced by the electrode filling solution, and is often much lower than is usually assumed. (3) With a small cell preparation that has an input resistance in the gigaohm range, measurements of single-channel conductance using a cell-attached patch electrode may be inaccurate because cell membrane potential does not remain constant as electrode potential is varied.

Animals↗

PubMed1985

Patch clamp studies of apical membranes of renal cortical collecting ducts.

Patch clamp techniques were used in study of the apical membrane of isolated renal cortical collecting ducts. Whereas on-the-cell patches (reported previously) gave channel activity due primarily to K+, isolated inside-out patches of the same membranes bathed with 150 mM Na+, 5 mM K+, and 1 mM Ca2+ gave channel activity due primarily to Na+. Na+ channels could remain either open or closed for periods of milliseconds to minutes. Although unitary currents of tenths of a pA were observed routinely, patch activity could change spontaneously between quiescent and violent with 'apparent' unitary currents of several pA. It was not possible to rule out the idea that the complex activity of the patches was due to synchronous or near synchronous openings/closings of several channels of identical unitary current. The unpredictable spontaneous changes of patch activity make difficult the design of experiments to test for the influence of agents expected or suspected to alter channel behavior.

Animals↗

PubMed1988

Analyzing stochastic events in multi-channel patch clamp data.

In an effort to understand the gating properties of ionic channels in biological membranes, an efficient method was developed to estimate the kinetic constants from opening-closing events of the channels. Our method is suitable to single channel patch-clamp recordings that contain several ionic channels functioning simultaneously. It is different from the maximum likelihood method previous developed by Horn and Lange, in that our method is a continuum approach and makes uses of analytic expressions of the probability density functions of the event times. Combinatorial analysis was necessary to correctly include more typical multi-channel recordings. This yields computationally quicker results than the method of Horn and Lange, which uses a discretized time series. Model-dependent portions of the code are minimal and easily modified. To illustrate the goodness of our method, we have generated the open-close processes of the patch-clamp records on a digital computer using the exponential random number generators. For multi-channel patches, we have introduced a few plausible approximations to make our algorithm more efficient. The soundness of the our approximations were tested with such measures as the fraction of the open state at time t, Popen (t), and frequencies of the number of openings per run. A copy of the computer code implementing this algorithm can be obtained from the authors.

Computer Simulation↗

PubMedDate not supplied

Ca2+ oscillations induced by histamine H1 receptor stimulation in HeLa cells: Fura-2 and patch clamp analysis.

The response of HeLa cells to histamine H1 receptor stimulation is characterized by periodic increases in cytosolic free Ca2+ concentration. The mechanisms underlying this oscillatory behaviour are not well understood. Fura-2 and patch clamp experiments carried out on HeLa cells have previously shown: (a) that Ca2+ oscillations are not initially dependent on the presence of external Ca2+, that external Ca2+ is required to maintain the oscillatory activity; (b) that a depolarization of the cell membrane leads to an inhibition of Ca2+ oscillations during the external Ca2+ dependent phase of the process; and (c) that Ca2+ oscillations can be abolished during this latter phase by the exogenous addition of Ca2+ channel blocking agents, such as Co2+ or La3+. The contribution of the inositol phosphate pathway to Ca2+ oscillations was more recently investigated in whole cell experiments performed with patch pipettes containing IP3 or the non-hydrolysable GTP analogue GTP-gamma S. Clear periodic current fluctuations were recorded using both patch pipette solutions. Assuming that the intracellular IP3 level remained constant under these conditions, these findings provide direct evidence that the Ca2+ oscillations in HeLa cells do not arise from a periodic production of IP3. The effect of the internal and external cell pH on the oscillatory process was also investigated in Fura-2 and patch clamp experiments. It was found that an increase in intracellular pH from 7.4 to 7.7 during the external Ca2+ dependent phase of the histamine stimulation abolishes the appearance of Ca2+ spikes whereas, a cellular acidification to pH 7.2 maintains or stimulates the Ca2+ oscillatory activity. The former effect was observed in the absence of Ca2+ in the bathing medium, indicating that the inhibitory action of alkaline pH was not related to a reduced Ca2+ entry. An increase in extracellular pH from 7.3 to 9.0 in contrast elicited an intracellular Ca2+ accumulation which resulted in most cases in an inhibition of the oscillatory process. This effect was dependent on external Ca2+ and was observed in alkaline internal pH conditions (pH 7.7). These observations suggest: (a) that the net Ca2+ influx in HeLa cells is strongly dependent on the cell internal and external pH; and (b) that the magnitude of this Ca2+ influx controls to a large extent the oscillation frequency. Finally, an inhibition of the histamine induced Ca2+ oscillatory activity was observed following the addition of the Ca(2+)-induced Ca(2+)-release (CICR) inhibitor adenine to the external medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗

PubMed2006

Microfluidic system for planar patch clamp electrode arrays.

We present a microfluidic system integrated with disposable cell interface partitions for simultaneous patch clamp recordings. Glass-supported poly(dimethylsiloxane) (PDMS) partitions, having a 2 microm air-blown aperture, were reversibly sealed to a microfluidic system including PDMS channels with isolation valves and microfabricated Ag/AgCl electrodes. Gigaseal recordings from RBL-1 cells were obtained with a 24% success rate. Simultaneous whole cell recordings from valve-isolated electrodes were obtained.

Animals↗