Electrical Activity Of Single Cells Research Articles

Soft electrodes cozy up to cells

Measuring the electrical activity of single cells gives biologists new insights into the heart and nervous system, but existing rigid electrodes made of metal or silicon can stress biological tissues and limit the quality of electrical measurements. Now, researchers have made squishy hydrogel electrodes that match the mechanical properties of living tissues and have shown that they can take better readings from heart and nerve cells (Proc. Natl. Acad. Sci. USA 2018, DOI: 10.1073/pnas.1810827115). The unnatural rigidity of flat electrodes or thin wires used to study the electrical activity of single cells can cause stress, leading cells to behave abnormally, including changing their gene-expression patterns. The material mismatch also prevents the cells from nestling up to the electrode and making strong contact. This physical gap causes impedance, or a muffled and noisy electrical signal. These problems are even more acute when working with cardiomyocytes, heart muscle cells that beat even

Talking to cells: semiconductor nanomaterials at the cellular interface.

The interface of biological components with semiconductors is a growing field with numerous applications. For example, the interfaces can be used to sense and modulate the electrical activity of single cells and tissues. From the materials point of view, silicon is the ideal option for such studies due to its controlled chemical synthesis, scalable lithography for functional devices, excellent electronic and optical properties, biocompatibility and biodegradability. Recent advances in this area are pushing the bio-interfaces from the tissue and organ level to the single cell and sub-cellular regimes. In this progress report, we will describe some fundamental studies focusing on miniaturizing the bioelectric and biomechanical interfaces. Additionally, many of our highlighted examples involve freestanding silicon-based nanoscale systems, in addition to substrate-bound structures or devices; the former offers new promise for basic research and clinical application. In this report, we will describe recent developments in the interfacing of neuronal and cardiac cells and their networks. Moreover, we will briefly discuss the incorporation of semiconductor nanostructures for interfacing non-excitable cells in applications such as probing intracellular force dynamics and drug delivery. Finally, we will suggest several directions for future exploration.

Density is Density - On the Relation Between Quantity of T-Type Ca2+ Channels and Neuronal Electrical Behavior

The electroresponsiveness fingerprint of a neuron reflects the types and distributions of the ionic channels that are embedded in the neuronal membrane as well as its morphology. Theoretical analysis shows that subtle changes in the density of channels can contribute substantially to the electroresponsive fingerprints of neurons. We have confirmed these predictions, using the dynamic clamp approach to emulate changes in channels' densities in neurons from the inferior olive. We demonstrate how the density of T-type channels determines the behavioral destiny of neurons. We argue that regulation of channel densities could be an efficient mechanism for controlling the electrical activity of single cells, as well as the output of neuronal networks.

A targeted extracellular approach for recording long-term firing patterns of excitable cells: a practical guide.

Excitable cells in many endocrine and neuronal systems display rhythms with periodicities on the order of many minutes. To observe firing patterns that represent the output of these rhythms requires a recording technique that can monitor electrophysiological activity for several hours without affecting cell behavior. A targeted extracellular approach (also known as loose-patch) accomplishes this objective. Because low resistance seals (<20 MΩ) do not influence the cell membrane and because the normal intracellular milieu is maintained, this approach is the least invasive method for monitoring the endogenous electrical activity of single cells. In this report, we detail our use of this technique to record the firing patterns of gonadotropin-releasing hormone (GnRH) neurons in brain slices continuously for several hours.

GHRP‐6‐Induced Changes in Electrical Activity of Single Cells in the Arcuate, Ventromedial and Periventricular Nucleus Neurones of a Hypothalamic Slice Preparation In Vitro

Journal of NeuroendocrinologyVolume 12, Issue 4 p. 377-378 Free Access GHRP-6-Induced Changes in Electrical Activity of Single Cells in the Arcuate, Ventromedial and Periventricular Nucleus Neurones of a Hypothalamic Slice Preparation In Vitro First published: 24 December 2001 https://doi.org/10.1046/j.1365-2826.2000.012004377.xAbout ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume12, Issue4April 2000Pages 377-378 RelatedInformation

GHRP-6-induced changes in electrical activity of single cells in the arcuate, ventromedial and periventricular nucleus neurones [correction of nuclei] of a hypothalamic slice preparation in vitro.

Previously, we demonstrated that systemic injection of the growth hormone secretagogue, growth hormone-releasing peptide (GHRP)-6, selectively activated cells in the hypothalamic arcuate nucleus, as reflected by increased electrical activity and induction of the immediate early gene c-fos. The growth hormone secretagogue receptor distribution is not confined to the arcuate nucleus, suggesting that additional sites of action may exist. In the present study we characterized the electrophysiological responses of cells in the arcuate nucleus, ventromedial nucleus and periventricular nucleus in an in-vitro hypothalamic slice preparation, following bath application of GHRP-6. Additionally, since central somatostatin administration has been shown to attenuate the induction of the c-fos gene by GHRP-6, we sought to determine whether the arcuate cells activated by GHRP-6 are also somatostatin-sensitive. Male Wistar rats (100-150 g body weight (BW)) were anaesthetized (urethane; 1.2 g/kg BW) and the brains removed. Coronal sections (400 microm thickness) were cut through a block of hypothalamus and were transferred to a slice chamber perfused with artificial cerebrospinal fluid. Forty-one arcuate nucleus cells were tested with bath application of 15 microm GHRP-6 for 10 min, 16 of which were tested subsequently (>30 min later) with application of 10 microM somatostatin. Following GHRP-6 administration, 19 cells (46. 3%) showed a significant increase in firing rate during the 15-min period after GHRP-6 application (P<0.001), 17 cells (41.5%) did not respond and the remaining five cells (12.2%) were significantly inhibited. Six of the eight arcuate nucleus cells that were excited by GHRP-6 were significantly inhibited by somatostatin. By contrast, five of the six arcuate nucleus cells that were unresponsive to GHRP-6 were also unresponsive to somatostatin. In the ventromedial nucleus, of 19 cells tested, eight cells (42.1%) were excited by GHRP-6, eight cells (42.1%) were unresponsive and the remaining three cells (15.8%) were significantly inhibited. Of 19 cells recorded in the periventricular nucleus, 13 (68.4%) were unresponsive to GHRP-6 and six (31.6%) were significantly inhibited. Thus, electrophysiological studies in vitro suggest that: (1) neurones in the hypothalamic arcuate nucleus, ventromedial nucleus and periventricular nucleus show changes in electrical activity in response to GHRP-6; and (2) the arcuate nucleus cells excited by GHRP-6 are also subject to inhibitory control by somatostatin.

Effects of Chemical and Surgical Ganglionectomy on Electrical Activity of the Pineal Gland of Male Rats

In order to elucidate further the role of sympathetic innervation for pineal function, the influence of sympathectomy on the spontaneous electrical activity of single cells in the pineal gland of adult male rats was investigated. Extracellular single-unit recordings were made during nighttime in the pineal gland of urethane-anesthetized, blinded adult male rats that had been treated neonatally with 6-hydroxydopamine, or that were ganglionectomized either during, or 12-16 h or 36-40 h, prior to the recording experiment. These experiments revealed that the excitatory influence of the sympathetic system on pineal nocturnal electrical activity can be abolished by either chemical sympathectomy of neonatal rats or surgical superior cervical ganglionectomy in adult animals.

Changes in the electrical activity of the rat pineal gland following stimulation of the cervical sympathetic ganglia

In order to elucidate the role of sympathetic innervation for pineal function, the influence of both unilateral and bilateral electrical stimulation of the superior cervical ganglia on the electrical activity of single cells in the rat pineal gland was investigated. These experiments revealed a clear influence on spontaneous electrical activity of single pinealocytes. About half of the units tested by unilateral stimulation exhibited either a graded continuous augmentation or inhibitions of different magnitude. In addition, ‘silent’ cells without spontaneous activity could be activated by sympathetic stimulation. Sequential and simultaneous bilateral stimulations showed that only a few cells could be influenced by both ganglia and in these cases the influence seemed to be additive. Some pineal cells do not appear to be under the control of the sympathetic nervous system.

Respiratory neurones of the ventrolateral nucleus of the solitary tract of cat: Vagal input, spinal connections and morphological identification

(1) Electrical activity of single cells was recorded extracellularly in the vicinity of the solitary tract complex in the medulla oblongata of pentobarbital anaesthetized, paralysed cats. The anatomical location and gross morphological properties of some of the neurones were determined by a fluorescent dye (Procion Yellow) injection technique. (2) Of a total of 279 cells studied, 261 cells fired rhythmically with some phase of the respiratory cycle, i.e., respiratory neurones. Most respiratory neurones (238 cells) discharged in phase with the phrenic, i.e., they were inspiratory neurones. (3) Most of the 73 anatomically identified cells were found in the ventrolateral nucleus of the solitary tract which proved a somewhat heterogenous nucleus with a roughly equal mixture of ‘inspiratory-vagal’, ‘inspiratory-non-vagal-spinal’ cells along with a few ‘inspiratory-expiratory’, expiratory and non-respiratory neurones. (4) Inspiratory neurones could be divided into 2 main groups on the basis of their vagal and spinal connections: (1) inspiratory neurones driven by electrical stimuli to the cervical vagus and influenced by lung inflations; (2) inspiratory neurones not influenced by vagal afferents but driven with short latency from the ventrolateral columns of the contralateral side of the spinal cord. (5) The ‘inspiratory-vagal’ cells showed inspiratory activity even when lung expansion in the inspiratory phase was prohibited, thus resembling the R β cells of von Baumgarten and Kanzow.

Some observations on the cerebral cortex with an ultramicro, membrane-covered, oxygen electrode.

The method of preparation of a micro platinum-in-glass membrane-covered electrode is described. The electrode has a tip diameter of 2–5μ and can be used for measuring oxygen tension in soft tissues such as brain. Its resolution is high enough to allow measurement of intercapillary oxygen gradients. If the tip is covered by a sufficiently thin membrane the electrode can be used to record electrical activity of single cells concurrently with oxygen tesion. The diffusion zones of oxygen around capillaries in the cortex of rat brain appear to be in the form of truncated cones.

Effect of sodium and potassium ions on the electrical activity of single cells in the lateral eye of the horseshoe crab.

The Journal of PhysiologyVolume 161, Issue 2 p. 319-343 ArticleFree Access Effect of sodium and potassium ions on the electrical activity of single cells in the lateral eye of the horseshoe crab R. Kikuchi, R. KikuchiSearch for more papers by this authorK. Naito, K. NaitoSearch for more papers by this authorI. Tanaka, I. TanakaSearch for more papers by this author R. Kikuchi, R. KikuchiSearch for more papers by this authorK. Naito, K. NaitoSearch for more papers by this authorI. Tanaka, I. TanakaSearch for more papers by this author First published: 01 May 1962 https://doi.org/10.1113/jphysiol.1962.sp006889Citations: 34AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume161, Issue2May 1, 1962Pages 319-343 RelatedInformation

Electrical activity of the isolated nerve-urinary bladder strip preparation of the rabbit.

The electrical activity of single cells of the smooth muscle of the isolated pelvic nerve-bladder strip preparation of the rabbit has been recorded by means of KCl-filled glass capillary microelectrodes. It was found that increasing the tension on the muscle either by stretching or by the addition of carbachol (3 µg/ml) to the bathing fluid causes a concomitant depolarization of the cell membrane. Spontaneous electrical activity and that elicited by stimulation of the nerve were similar and consisted of slow waves of depolarization of a 3–5 sec duration and spikes superimposed upon the depolarization phase of the slow wave. The spikes varied from 5 to 35 mv with no overshoot. Excitability of cells varied from one in which no response to tetanic stimulation of the nerve was seen to one which exhibited a series of spikes to a single shock. It was shown that slow waves and spikes could occur out of phase with the dominant activity of the whole muscle. Latency to a single shock to the nerve was found to be quite consistent for the same cell. However, a marked variation in latency was found among different cells of the same preparation.

Metabolism and electrical activity of the heart: action of 2-4-dinitrophenol and ATP.

The effects of DNP on the electrical activity of single cells of the sinus node, right auricle and A-V node, were studied with microelectrodes. It was observed that this agent caused an initial tachycardia followed by a bradycardia, a decrease in the duration of the action potential, a decrease of the resting potential and a decrease in the slope of diastolic depolarization of pacemaker tissues. A complete inhibition of the electrical activity was observed in 45 minutes after the addition of DNP to the perfusion fluid. A similar result was obtained with sodium azide. A significant recovery of the electrical activity was obtained with the use of a system with DNP and ATP. A possible increase of the extracellular potassium concentration produced by DNP similar to that observed in skeletal muscle is discussed. An incomplete loss of the resting potential observed with DNP makes it probable that at least a fraction of the resting potential is independent of the energy supplied by oxidative phosphorylation.