SOME ELECTRICAL CHARACTERISTICS OF SUCROSE-WASHED FROG SARTORIUS MUSCLE

1966 ◽  
Vol 44 (4) ◽  
pp. 663-674 ◽  
Author(s):  
G. W. Mainwood
Keyword(s):  
Carbon Dioxide ◽  
Transmembrane Potential ◽  
Sucrose Solution ◽  
Surrounding Medium ◽  
Carbon Dioxide Concentration ◽  
Specific Effect ◽  
Sartorius Muscle ◽  
Extracellular Potassium ◽  
Extracellular Potassium Concentration ◽  
Frog Sartorius

Transmembrane potential measurements were carried out with microelectrodes in frog sartorius muscles washed in buffered sucrose solution. After an initial fall the potential returns to a level determined by the extracellular potassium concentration. After about 20 minutes of washing, the cells develop a response to carbon dioxide dissolved in the surrounding medium. Increasing the extracellular carbon dioxide concentration leads to a reversible fall in transmembrane potential. This appears to be a specific effect of carbon dioxide since lowering the pH in the absence of CO2 does not cause a significant potential change. It is postulated that this effect may be due to an efflux of bicarbonate ions.

scholarly journals The relation between sodium ion content and efflux of labelled sodium ions from yeast

1968 ◽  
Vol 107 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Elizabeth Dee ◽  
Edward J. Conway
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Concentration ◽  
Sartorius Muscle ◽  
Free Medium ◽  
Ion Content ◽  
Frog Sartorius Muscle ◽  
Na Efflux ◽  
K Concentration ◽  
Frog Sartorius ◽  
External K

1. The activity of the Na+ pump in an Na+-rich yeast was compared with that in an Na+-rich frog sartorius muscle, and found to be very similar to it over the first hour if both were immersed in fluid containing 104mm-Na+ plus 10mm-K+. 2. The efflux of labelled Na+ from an Na+-rich yeast into an Na+-free medium was investigated. In this Na+-free medium, Li+ or choline replaced the Na+, and the efflux–content curves obtained with either of these ions were very similar. The curves were sigmoid, reaching or approaching a saturation at the higher internal Na+ concentrations. 3. The curves obtained with yeast resembled those similarly obtained with frog sartorius muscle by Keynes & Swan (1959), Mullins & Frumento (1963), Harris (1965) and Keynes (1965). The slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ concentration in the cells reached its highest value at an internal Na+ concentration of 15m-equiv./kg. (27m-equiv./l. of cell water). 4. The effect of external K+ concentration on the efflux–content relationship was examined. An increased K+ concentration was found to increase the Na+ efflux by raising the saturation value, which is similar to observations made by Harris (1965) with frog muscle. 5. The effect of increasing the external carbon dioxide concentration was investigated. No effect on the slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ content was noticed even when the yeast suspension was equilibrated with 100% carbon dioxide. There was, however, a decrease in the amount of Na+ efflux on equilibrating the solution with carbon dioxide.

Effects of step changes in pH on isometric tetanic tension of toad sartorius muscle

1983 ◽  
Vol 61 (8) ◽  
pp. 830-835 ◽  
Author(s):  
J. M. Renaud ◽  
E. Don Stevens
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Rapid Change ◽  
Carbon Dioxide Concentration ◽  
Physiological Solution ◽  
Acclimation Temperature ◽  
Sartorius Muscle ◽  
Bathing Solution ◽  
Ph Change ◽  
Tetanic Tension

The effect of a rapid change in pHe (pH of bathing solution) on the isometric tetanic tension developed by sartorius muscles of toads acclimated to 5 and 25 °C was measured at 5 and 25 °C. The pH was altered by changing the carbon dioxide concentration of a bicarbonate buffered physiological solution. Acclimation temperature did not modify the response to a rapid change in pH, but test temperature did. Following a pH decrease from 9.0 to 6.0, tetanic tension decreased at a faster rate at 5 °C than at 25 °C. A new steady state was reached in 15 min at 5 °C but in 40 min at 25 °C. Following a pH increase from 6.0 to 8.5, tetanic tension increased at a faster rate at 25 °C than at 5 °C. A new steady state was reached in 60 min at 5 °C but in 10 min at 25 °C. We conclude that the rate of carbon dioxide diffusion through the sartorius muscle is only one factor that determines how rapidly tetanic tension changes following the step change in pH, and that muscle resists pH change more effectively at higher temperatures.

Steady-state effects of extracellular potassium concentration on vascular smooth muscle reactivity

1981 ◽  
Vol 241 (2) ◽  
pp. H217-H223
Author(s):  
N. Skaug ◽  
R. Detar
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Transmembrane Potential ◽  
Potassium Concentration ◽  
Maximum Level ◽  
Extracellular Potassium ◽  
Positive Component ◽  
Negative Component ◽  
Small Arteries ◽  
Extracellular Potassium Concentration

Helical strips cut from small arteries taken from rabbit skeletal muscle were used to determine the steady-state effects of extracellular potassium concentration ([K]o) on the reactivity to epinephrine or norepinephrine. It was found that reactivity observed under the usual steady-state conditions (termed "usual reactivity") was depressed as steady-state [K]o was reduced from 8 to 1 mM. This depression reflected concurrent changes in two components of contraction: 1) a positive component (evaluated as reactivity during brief exposure to 10(-6) M ouabain) decreased when steady-state [K]o was reduced below approximately 5 mM, and 2) a negative component (evaluated indirectly as enhancement of reactivity produced by 10(-6) M ouabain) increased to a peak when steady-state [K]o was reduced from 8 to approximately 4-5 mM and decreased below this peak when steady-state [K]o was reduced below approximately 4-5 mM. It was also found that the magnitude of a reserve ouabain-sensitive negative component (demonstrated by abruptly increasing [K]o to 10.18 mM) increased from a minimum to a maximum level when steady-state [K]o was reduced from 6 to 3 mM. It is suggested that the effects of [K]o on the positive component of contraction, defined earlier as contractility, primarily involve some factor(s) other than transmembrane potential, whereas the effects on the negative component involve transmembrane potential exclusively and, in particular, the electrogenic potential. The latter suggestion constitutes the basis for use of the term electrogenesis in reference to this negative component.

Communication: Photoinduced Carbon Dioxide Binding with Surface-Functionalized Silicon Quantum Dots

2018 ◽  
Author(s):  
Oscar A. Douglas-Gallardo ◽  
Cristián Gabriel Sánchez ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Carbon Dioxide ◽  
Quantum Dots ◽  
Atmospheric Carbon Dioxide ◽  
Density Functional ◽  
Tight Binding ◽  
Carbon Dioxide Concentration ◽  
Research Area ◽  
Silicon Quantum Dots ◽  
Dependent Model ◽  
Photoinduced Charge

<div> <div> <div> <p>Nowadays, the search of efficient methods able to reduce the high atmospheric carbon dioxide concentration has turned into a very dynamic research area. Several environmental problems have been closely associated with the high atmospheric level of this greenhouse gas. Here, a novel system based on the use of surface-functionalized silicon quantum dots (sf -SiQDs) is theoretically proposed as a versatile device to bind carbon dioxide. Within this approach, carbon dioxide trapping is modulated by a photoinduced charge redistribution between the capping molecule and the silicon quantum dots (SiQDs). Chemical and electronic properties of the proposed SiQDs have been studied with Density Functional Theory (DFT) and Density Functional Tight-Binding (DFTB) approach along with a Time-Dependent model based on the DFTB (TD-DFTB) framework. To the best of our knowledge, this is the first report that proposes and explores the potential application of a versatile and friendly device based on the use of sf -SiQDs for photochemically activated carbon dioxide fixation. </p> </div> </div> </div>

Prepotentials and unidirectional propagation in myocardium

1961 ◽  
Vol 201 (5) ◽  
pp. 873-880 ◽  
Author(s):  
T. Hoshiko ◽  
Nick Sperelakis
Keyword(s):  
Current Flow ◽  
Reverse Direction ◽  
Sartorius Muscle ◽  
Potential Response ◽  
Ringer’S Solution ◽  
Current Pulses ◽  
Negative Current ◽  
Reversed Polarity ◽  
Bidirectional Propagation ◽  
Frog Sartorius

In frog ventricular strips bathed in Ca-free Ringer's solution containing 6–30 mm/liter Mg and treated with conditioning current pulses, propagation became impaired. An exaggerated foot, or prepotential, was consistently more prominent when the conditioned strip was stimulated from one end than from the other. Occasionally a prepotential in isolation alternated with a prepotential plus action potential response. After further treatment with current pulses, propagation failed in the direction of negative current flow. Thresholds of impaled cells were identical. Bidirectional propagation was restored in Ringer's solution. Conditioning pulses of reversed polarity induced unidirectional propagation in the reverse direction. Propagation in frog sartorius muscle was not blocked under similar conditions. Prepotentials and unidirectional propagation may be explained by junctional transmission from cell to cell.

Hyperspectral characteristics and leaf area index monitoring of rice (Oryza sativa L.) under carbon dioxide concentration enrichment

2021 ◽  
Vol 54 (3) ◽  
pp. 231-243
Author(s):  
Chao Liu ◽  
Zhenghua Hu ◽  
Rui Kong ◽  
Lingfei Yu ◽  
Yuanyuan Wang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Oryza Sativa ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Oryza Sativa L ◽  
Carbon Dioxide Concentration ◽  
Area Index
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