Conventional Voltage Clamping With Two Intracellular Microelectrodes

1985 ◽  
pp. 47-94 ◽  
Author(s):  
Alan S. Finkel ◽  
Peter W. Gage
Keyword(s):  
Intracellular Microelectrodes ◽  
Voltage Clamping

Electrogenic, K + -dependent chloride transport in locust hindgut

1982 ◽  
Vol 299 (1097) ◽  
pp. 585-595 ◽  
Keyword(s):  
Chloride Transport ◽  
Passive Movement ◽  
Water Reabsorption ◽  
Experimental Conditions ◽  
Cl Transport ◽  
Neuropeptide Hormone ◽  
Flux Measurements ◽  
Ion Sensitive Microelectrodes ◽  
Voltage Clamping ◽  
Electrochemical Potentials

Potassium chloride is the major salt recycled in most insect excretory systems. Ion and water reabsorption occur in the rectum by active transport of Cl- and largely passive movement of K+. Both these processes are stimulated several fold by a neuropeptide hormone acting via cyclic AMP (cAMP). This Cl- transport process was investigated by using intracellular ion-sensitive microelectrodes, radiotracer flux measurements, voltage clamping, ion substitutions and inhibitors. The mucosal entry step for Cl- is energy-requiring and highly selective, and is stimulated directly by cAMP and luminal K +. Under some experimental conditions, measured electrochemical potentials for cations across the mucosal membrane are too small to drive Cl- entry by NaCl or KC1 cotransport mechanisms; moreover, net 36C1- flux is independent of the apical Na+ potential. Similarly no evidence for a HCO 3 -Cl- exchange was obtained. We conclude that Cl- transport in locust gut is different from mechanisms currently proposed for vertebrate tissues.

scholarly journals The Spectral Sensitivities of Single Cells in the Median Ocellus of Limulus

1969 ◽  
Vol 54 (5) ◽  
pp. 636-649 ◽  
Author(s):  
John Nolte ◽  
Joel E. Brown
Keyword(s):  
Visible Light ◽  
Spectral Sensitivity ◽  
Uv Light ◽  
Single Cells ◽  
Chromatic Adaptation ◽  
Sensitivity Curve ◽  
Receptor Cells ◽  
Intracellular Microelectrodes ◽  
Median Ocellus ◽  
Spectral Sensitivity Curve

The spectral sensitivities of single Limulus median ocellus photoreceptors have been determined from records of receptor potentials obtained using intracellular microelectrodes. One class of receptors, called UV cells (ultraviolet cells), depolarizes to near-UV light and is maximally sensitive at 360 nm; a Dartnall template fits the spectral sensitivity curve. A second class of receptors, called visible cells, depolarizes to visible light; the spectral sensitivity curve is fit by a Dartnall template with λmax at 530 nm. Dark-adapted UV cells are about 2 log units more sensitive than dark-adapted visible cells. UV cells respond with a small hyperpolarization to visible light and the spectral sensitivity curve for this hyperpolarization peaks at 525–550 nm. Visible cells respond with a small hyperpolarization to UV light, and the spectral sensitivity curve for this response peaks at 350–375 nm. Rarely, a double-peaked (360 and 530 nm) spectral sensitivity curve is obtained; two photopigments are involved, as revealed by chromatic adaptation experiments. Thus there may be a small third class of receptor cells containing two photopigments.

A Novel IGBT With Voltage-Clamping for Turn-on Overshoot Suppression Under Hard-Switching

2021 ◽  
Vol 68 (10) ◽  
pp. 5326-5329
Author(s):  
Gaoqiang Deng ◽  
Zhen Ma ◽  
Xiaorong Luo ◽  
Xintong Xie ◽  
Congcong Li ◽  
...  
Keyword(s):  
Turn On ◽  
Voltage Clamping

The Electrical Properties of a Crustacean Sensory Dendrite

1979 ◽  
Vol 78 (1) ◽  
pp. 1-27
Author(s):  
MAURIZIO MIROLLI
Keyword(s):  
Time Course ◽  
Short Circuit ◽  
Input Resistance ◽  
Scylla Serrata ◽  
Current Pulses ◽  
Length Constant ◽  
Voltage Transient ◽  
Intracellular Microelectrodes ◽  
Voltage Transients ◽  
Sensory Endings

1. The input properties and the response to stretch of a coxal receptor, the S fibre of the crab Scylla serrata, were studied using two and three intracellular microelectrodes. 2. In the relaxed receptor the transmembrane potential ranged from about −60 to −70 mV, and the input resistance, RT, from 1 to 3 MΩ. The input IV relationship, studied by injecting slow-rising current ramps, was not linear either in the hyperpolarizing or in the depolarizing quadrants. 3. Low values of RT and a linear IV relationship were associated with a large leakage of the microelectrodes. 4. The response to step stretches was complex, consisting of an initial depolarizing transient, Vα, and a steady-state depolarizing plateau, V8. Both Vα and V8 propagated with decrement in the fibre which was about 9 mm long. The spatial decrement of Vα and V8 was equal to that of the response to distally injected current pulses of comparable duration and amplitude. 5. On the basis of the spatial decrement of both Vα and V8 the dendrite can be considered equivalent, for current flowing from its distal to its proximal end, to a semi-infinite cable having a length constant of between 4 and 6 cm. 6. The voltage transients recorded in response to long current pulses reached 84% of their final value in a time (t84%) ranging from 150 to 180 ms in fibres in which RT was 2 Mω or larger. t84% was smaller in fibres having a lower RT. 7. The time course of the transients recorded in response to injected current pulses deviated from the semi-infinite cable model in a manner suggesting the presence of a partial short circuit. For this reason the membrane time constant of the fibre is considered larger (by an undetermined amount) than t84%. 8. The fibre presented less resistance to current flowing from its proximal to its distal end than to current flowing in the opposite direction. For this reason, and also because of the time course of the voltage transient, it is concluded that the distal sensory endings of the fibre have the properties of a leaky end termination, even in the non-stimulated receptors.

Low-Voltage Clamping TVS for Data Line Protection

2021 ◽  
Vol 58 (5) ◽  
pp. 3-13
Author(s):  
Hee-Won Jang ◽  
Hyun-Sik Kim ◽  
Seong-Ho Ham
Keyword(s):  
Low Voltage ◽  
Data Line ◽  
Voltage Clamping

Improved defibrillator waveform safety factor with biphasic waveforms

1983 ◽  
Vol 245 (1) ◽  
pp. H60-H65 ◽  
Author(s):  
J. L. Jones ◽  
R. E. Jones
Keyword(s):  
Safety Factor ◽  
Voltage Gradient ◽  
Excitation Threshold ◽  
Efficacy And Safety ◽  
Myocardial Cells ◽  
Safety Factors ◽  
Adult Type ◽  
Intracellular Microelectrodes ◽  
Cultured Myocardial Cells

Excitation thresholds and arrhythmias were studied in "adult-type" cultured chick embryo myocardial cells after electric field stimulation with biphasic, truncated, and rectified underdamped RLC (resistance-inductance-capacitance) type waveforms, to test the hypothesis that the negative phase of biphasic waveforms ameliorates membrane dysfunction induced by the initial positive portion. Photocell mechanograms and intracellular microelectrodes monitored extrasystoles and depolarization-induced arrhythmias. Rectifying or truncating biphasic waveforms did not alter the excitation threshold. However, shock intensities producing specific postshock arrhythmias or a specific severity of postshock prolonged depolarization differed significantly when biphasic waveforms were truncated or rectified. The voltage gradient producing a specific dysfunction was 12-14% lower for the truncated version than for the biphasic; that for the rectified version was 17-27% lower than for the biphasic version (although both contained the same energy). Safety factor, the ratio between shock intensity producing specific dysfunction and that producing excitation, was determined for each waveform. Biphasic waveforms had larger safety factors than truncated or rectified waveforms. Since safety factor, as measured in cultured myocardial cells, closely corresponds with in situ defibrillating effectiveness (14), the significantly higher safety factors of biphasic waveforms suggest that carefully shaped biphasic waveforms might improve the efficacy and safety of cardiac defibrillation procedures.

Voltage clamping induces resistance and current-voltage plot changes in frog gastric mucosa

1984 ◽  
Vol 246 (5) ◽  
pp. G574-G579
Author(s):  
G. W. Kidder ◽  
M. G. Elrod
Keyword(s):  
Gastric Mucosa ◽  
Membrane Resistance ◽  
Previous Model ◽  
Half Time ◽  
Ion Content ◽  
Zero Current ◽  
Current Voltage ◽  
Measured Resistance ◽  
Voltage Clamping ◽  
Voltage Transients

Changing the potential across the isolated frog gastric mucosa by voltage clamping changes the measured resistance of the tissue in two ways. An immediate change in resistance results from changing the measuring position on the nonlinear current-voltage (I-V) plot. Subsequent to this, the resistance changes slowly with a half-time of about 3 min, a change that is not predicted by a previous model for voltage transients and that implies slow changes in membrane resistance following changes in intracellular ion content. The I-V plot over the range examined shows three breakpoints; changing clamp voltage alters the position of two of these breakpoints as well as the slope of the connecting resistances. The central breakpoint agrees with the potential at zero current and varies with it as the clamp potential is changed, as predicted from a diode model for breakpoint generation.

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