Useful Circuits for Voltage Clamping With Microelectrodes

1985 ◽  
pp. 9-24
Author(s):  
Alan S. Finkel
Keyword(s):  
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.

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

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

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.

scholarly journals Nonanticoagulant heparin reduces myocyte Na+ and Ca2+ loading during simulated ischemia and decreases reperfusion injury

2010 ◽  
Vol 298 (1) ◽  
pp. H102-H111 ◽  
Author(s):  
William H. Barry ◽  
Xiu Q. Zhang ◽  
Michael E. Halkos ◽  
Jakob Vinten-Johansen ◽  
Noriko Saegusa ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Ventricular Myocytes ◽  
Myocardial Necrosis ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Metabolic Inhibition ◽  
Early Reperfusion ◽  
Simulated Ischemia ◽  
Sea Anemone Toxin ◽  
Voltage Clamping

Heparin desulfated at the 2- O and 3- O positions (ODSH) decreases canine myocardial reperfusion injury. We hypothesized that this occurs from effects on ion channels rather than solely from anti-inflammatory activities, as previously proposed. We studied closed-chest pigs with balloon left anterior descending coronary artery occlusion (75-min) and reperfusion (3-h). ODSH effects on [Na+]i (Na Green) and [Ca2+]i (Fluo-3) were measured by flow cytometry in rabbit ventricular myocytes after 45-min of simulated ischemia [metabolic inhibition with 2 mM cyanide, 0 glucose, 37°C, pacing at 0.5 Hz; i.e., pacing-metabolic inhibition (PMI)]. Na+/Ca2+ exchange (NCX) activity and Na+ channel function were assessed by voltage clamping. ODSH (15 mg/kg) 5 min before reperfusion significantly decreased myocardial necrosis, but neutrophil influx into reperfused myocardium was not consistently reduced. ODSH (100 μg/ml) reduced [Na+]i and [Ca2+]i during PMI. The NCX inhibitor KB-R7943 (10 μM) or the late Na+ current ( INa-L) inhibitor ranolazine (10 μM) reduced [Ca2+]i during PMI and prevented effects of ODSH on Ca2+ loading. ODSH also reduced the increase in Na+ loading in paced myocytes caused by 10 nM sea anemone toxin II, a selective activator of INa-L. ODSH directly stimulated NCX and reduced INa-L. These results suggest that in the intact heart ODSH reduces Na+ influx during early reperfusion, when INa-L is activated by a burst of reactive oxygen production. This reduces Na+ overload and thus Ca2+ influx via NCX. Stimulation of Ca2+ extrusion via NCX later after reperfusion may also reduce myocyte Ca2+ loading and decrease infarct size.

scholarly journals Enhanced dynamic voltage clamping capability of Clustered IGBT at turn-off period

2016 ◽  
Vol 29 (1) ◽  
pp. 1-10
Author(s):  
Hong Long ◽  
Mark Sweet ◽  
Sankara Narayanan
Keyword(s):  
Numerical Evaluation ◽  
Load Condition ◽  
Operating Conditions ◽  
Current Gain ◽  
Power Devices ◽  
Inductive Load ◽  
Dynamic Voltage ◽  
Voltage Clamping ◽  
Safe Operating ◽  
Off Time

One of the critical requirements for high power devices is to have rugged and reliable capability against hash operating conditions. In this paper, we present the dynamic voltage clamping capability of 3.3kV Field Stop Clustered IGBT devices under extreme inductive load condition. It shows that PMOS trench gate CIGBT structure with outstanding performance of fast turn-off time and low over-shoot voltage. Further optimization of current gain of CIGBT structure is analyzed through numerical evaluation. A step further in the safe operating area has been achieved for high voltage devices by CIGBT technology.

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