scholarly journals Estimation of the membrane potential of cultured macrophages from the fast potential transient upon microelectrode entry

1983 ◽  
Vol 96 (3) ◽  
pp. 796-801 ◽  
Author(s):  
C Ince ◽  
DL Ypey ◽  
R Van Furth ◽  
AA Verveen
Keyword(s):  
Membrane Potential ◽  
Single Cells ◽  
Membrane Resistance ◽  
Peritoneal Macrophages ◽  
Mean Value ◽  
Membrane Potentials ◽  
Isolated Cells ◽  
Real Value ◽  
Mouse Peritoneal Macrophages ◽  
Peak Value

Analysis of membrane potential recordings upon microelectrode impalement of four types of macrophages (cell lines P388D1 and PU5-1.8, cultured mouse peritoneal macrophages, and cultured human monocytes) reveals that these cells have membrane potentials at least two times more negative than sustained potential values (E(s)) frequently reported. Upon microelectrode entry into the cell (P388D1), the recorded potential drops to a peak value (E(p)) (mean -37 mV for 50 cells, range -15 to -70 mV) within 2 ms, after which it decays to a depolarized potential (E(n)) (mean -12 mV) in about 20 ms. Thereafter, the membrane develops one or a series of slow hyperpolarizations before a final sustained membrane potential (E(s)) (mean -14 mV, range -5 to -40) is established. The mean value of the peak of the first hyperpolarization (E(h)) is -30 mV (range -10 to -55 mV). The initial fast peak transient, measured upon microelectrode entry, was first described and analyzed by Lassen et al. (Lassen, U.V., A.M. T. Nielson, L. Pape, and L. O. Simonsen, 1971, J. Membr. Biol. 6:269-288 for other change in the membrane potential from its real value before impalement to a sustained depolarized value. This was shown to be true for macrophages by two-electrode impalements of single cells. Values of E(p), E(n), E(h), E(s), and membrane resistance (R(m)) measured for the other macrophages were similar to those of P388D1. From these results we conclude that E(p) is a better estimate of the true membrane potential of macrophages than E(s), and that the slow hyperpolarizations upon impalement should be regarded as transient repolarizations back to the original membrane potentials. Thus, analysis of the initial fast impalement transient can be a valuable aid in the estimation of the membrane potential of various sorts of small isolated cells by microelectrodes.

Some bio-electric parameters of early Xenopus embryos

Development ◽  
1970 ◽  
Vol 24 (3) ◽  
pp. 535-553
Author(s):  
J. F. Palmer ◽  
Christine Slack
Keyword(s):  
Membrane Potential ◽  
South African ◽  
Developmental Stages ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Mean Value ◽  
Cell Junctions ◽  
Current Spread ◽  
Intracellular Microelectrodes ◽  
Junctional Resistance

Membrane potential and resistance were measured in eggs, cleavage stages and blastulae of the South African toad Xenopus laevis, using intracellular microelectrodes. The membrane potential increased from −6·5 ± 2mV in eggs to −57 ± 8·0mV at the mid-blastula stage. The input resistance of fertile eggs ranged from 0·5 MΩ to 5·0 MΩ corresponding to a specific resistance of 20–200kΩcm2. During the first two or three division cycles the input resistance usually decreased by a factor of 2–10 and then subsequently rose during the blastula stages from a mean value of 600 ± 100kΩ at stage 5 to 2·0 ± 0·5 MΩ at stage 8. At all developmental stages examined, point polarization of a surface cell in the embryo by rectangular current pulses of 0·5−6 × 10−8 A produced voltage deflexions in other surface cells. This was seen even when several (7–8) cell junctions intervened between the current passing and voltage recording microelectrodes at distances of more than 1 mm. These measurements suggest that the junctional resistance is low compared with that at the surface, though the geometrical arrangement of cells is not favourable for calculation of absolute values of membrane resistance. Current spread between cells occurred apparently less easily during mid-blastula stages than at earlier stages in development, perhaps indicating an increase in junctional resistance during development. A comparison has been drawn between the present measurements and similar ones made in another amphibian, Triturus.

scholarly journals Membrane Potential of Brown Adipose Tissue

1968 ◽  
Vol 52 (6) ◽  
pp. 925-940 ◽  
Author(s):  
L. Girardier ◽  
J. Seydoux ◽  
T. Clausen
Keyword(s):  
Adipose Tissue ◽  
Membrane Potential ◽  
Brown Adipose Tissue ◽  
Membrane Resistance ◽  
Mean Value ◽  
Extracellular Potassium ◽  
Bicarbonate Buffer ◽  
Interscapular Brown Adipose Tissue ◽  
Extracellular Potassium Concentration ◽  
Brown Adipose

Membrane potentials were recorded in isolated segments of interscapular brown adipose tissue from rats. After equilibration at 29°C in Krebs-Ringer bicarbonate buffer a mean value of -51 ± 4 mv (SD) was found. This level could be maintained for up to 5 hr. The mean effective membrane resistance was 1.35 ± 0.45 megohm. The membrane potential was a function of the extracellular potassium concentration. Ouabain (10-6-10-3 M) and incubation in K-free buffer produced progressive depolarization. Epinephrine and norepinephrine in concentrations as low as 10-8 g/ml produced a prompt depolarization. Cooling of the tissue and lowering of the oxygen tension caused a marked and reversible decrease in the membrane potential. In tissue obtained from cold-adapted rats, the membrane potential was considerably diminished. 6Assuming that the membrane potential is some function of the Na permeability of the plasma membrane it is suggested that an increase in the rate of active Na-K transport and ensuing ADP formation might contribute to the increase in respiration seen during exposure to thermogenic stimuli.

scholarly journals Inferring neuronal ionic conductances from membrane potentials using CNNs

2019 ◽  
Author(s):  
Roy Ben-Shalom ◽  
Jan Balewski ◽  
Anand Siththaranjan ◽  
Vyassa Baratham ◽  
Henry Kyoung ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Membrane Resistance ◽  
Neuronal Model ◽  
Membrane Potentials ◽  
Training Data ◽  
Neuronal Membrane ◽  
Neuron Models ◽  
Input Stimulus ◽  
Spatially Resolved ◽  
Ionic Conductances

AbstractThe neuron is the fundamental unit of computation in the nervous system, and different neuron types produce different temporal patterns of voltage fluctuations in response to input currents. Understanding the mechanism of single neuron firing patterns requires accurate knowledge of the spatial densities of diverse ion channels along the membrane. However, direct measurements of these microscopic variables are difficult to obtain experimentally. Alternatively, one can attempt to infer those microscopic variables from the membrane potential (a mesoscopic variable), or features thereof, which are more experimentally tractable. One approach in this direction is to infer the ionic densities as parameters of a neuronal model. Traditionally this is done using a Multi-Objective Optimization (MOO) method to minimize the differences between features extracted from a simulated neuron’s membrane potential and the same features extracted from target data. Here, we use Convolutional Neural Networks (CNNs) to directly regress generative parameters (e.g., ionic conductances, membrane resistance, etc.,) from simulated time-varying membrane potentials in response to an input stimulus. We simulated diverse neuron models of increasing complexity (Izikivich: 4 parameters; Hodgkin-Huxley: 7 parameters; Mainen-Sejnowski: 10 parameters) with a large range of variation in the underlying parameter values. We show that hyperparameter optimized CNNs can accurately infer the values of generative variables for these neuron models, and that these results far surpass the previous state-of-the-art method (MOO). We discuss the benefits of optimizing the CNN architecture, improvements in accuracy with additional training data, and some observed limitations. Based on these results, we propose that CNNs may be able to infer the spatial distribution of diverse ionic densities from spatially resolved measurements of neuronal membrane potentials (e.g. voltage imaging).

In Vivo Dynamic Clamp Study of Ih in the Mouse Inferior Colliculus

2010 ◽  
Vol 104 (2) ◽  
pp. 940-948 ◽  
Author(s):  
A. P. Nagtegaal ◽  
J.G.G. Borst
Keyword(s):  
Membrane Potential ◽  
Inferior Colliculus ◽  
Single Cells ◽  
Membrane Resistance ◽  
Resting Membrane Potential ◽  
Dynamic Clamp ◽  
Small Contribution ◽  
Functional Relevance ◽  
Rebound Spiking

Approximately half of the cells in the mouse inferior colliculus have the hyperpolarization-activated mixed cation current Ih, yet little is known about its functional relevance in vivo. We therefore studied its contribution to the processing of sound information in single cells by making in vivo whole cell recordings from the inferior colliculus (IC) of young-adult anesthetized C57Bl/6 mice. Following pharmacological block of the endogenous channels, a dynamic clamp approach allowed us to study the responses to current injections or auditory stimuli in the presence and absence of Ih within the same neuron, thus avoiding network or developmental effects. The presence of Ih changed basic cellular properties, including depolarizing the resting membrane potential and decreasing resting membrane resistance. Sound-evoked excitatory postsynaptic potentials were smaller but at the same time reached a more positive membrane potential when Ih was present. With Ih, a subset of cells showed rebound spiking following hyperpolarizing current injection. Its presence also changed more complex cellular properties. It decreased temporal summation in response to both hyperpolarizing and depolarizing repetitive current stimuli, and resulted in small changes in the cycle-averaged membrane potential during sinusoidal amplitude modulated (SAM) tones. Furthermore, Ih minimally decreased the response to a tone following a depolarization, an effect that may make a small contribution to forward masking. Our results thus suggest that previously observed differences in IC cells are a mixture of direct effects of Ih and indirect effects due to the change in membrane potential or effects due to the co-expression with other channels.

Fluorescent potentiometric dyes for membrane-potential imaging

1994 ◽  
Vol 52 ◽  
pp. 166-167
Author(s):  
Leslie M. Loew
Keyword(s):  
Membrane Potential ◽  
Single Cells ◽  
Quantitative Imaging ◽  
Optical Recording ◽  
Biological Processes ◽  
Major Focus ◽  
The Past ◽  
Excitable Systems ◽  
Major Application ◽  
The Impact

A major application of potentiometric dyes has been the multisite optical recording of electrical activity in excitable systems. After being championed by L.B. Cohen and his colleagues for the past 20 years, the impact of this technology is rapidly being felt and is spreading to an increasing number of neuroscience laboratories. A second class of experiments involves using dyes to image membrane potential distributions in single cells by digital imaging microscopy - a major focus of this lab. These studies usually do not require the temporal resolution of multisite optical recording, being primarily focussed on slow cell biological processes, and therefore can achieve much higher spatial resolution. We have developed 2 methods for quantitative imaging of membrane potential. One method uses dual wavelength imaging of membrane-staining dyes and the other uses quantitative 3D imaging of a fluorescent lipophilic cation; the dyes used in each case were synthesized for this purpose in this laboratory.

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