scholarly journals Ionic Relations of Cells of Chara Australls X. Effects of Bicarbonate Ions on Electrical Properties

1965 ◽  
Vol 18 (4) ◽  
pp. 789 ◽  
Author(s):  
AB Hope
Keyword(s):  
Electrical Properties ◽  
External Medium ◽  
Membrane Resistance ◽  
Potential Difference ◽  
Bicarbonate Ions ◽  
Ionic Relations

When bicarbonate ions were added to the external medium the plasmalemma of cells of Ohwra australis became hyperpolarized. The potential difference (p.d.) frequently changed from -150 or -160 mY to -200 or -220 mY. An increal!El in membrane resistance also occurred.

scholarly journals Ionic Relations of Cells of Ohara Australis R.BR. IV. Membrane Potential Differences and Resistances

1961 ◽  
Vol 14 (1) ◽  
pp. 26 ◽  
Author(s):  
AB Hope ◽  
NA Walker
Keyword(s):  
Cell Wall ◽  
Field Equation ◽  
Membrane Potential ◽  
Cytoplasmic Membrane ◽  
External Medium ◽  
Voltage Characteristic ◽  
Potential Difference ◽  
Constant Field ◽  
Sodium Ions ◽  
Ionic Relations

Experiments are described in which the electric potential difference and resistance between the cytoplasm and the external medium were measured in cells of Ohara australi8. The method was designed to eliminate the effect of the negatively charged Donnan system of the cell wall. Both the potential difference and the resistance are attributed to the outer cytoplasmic membrane. It is shown that they may be quantitatively explained by the passive diffusion of potassium and sodium ions across the membrane with permeabilities of the order of 10-5 and 10-8 cm sec-1 respectively. The resistance-voltage characteristic of the membrane is accurately predicted by the constant field equation of Goldman (1943). The ignificance of these findings is discussed.

Thermal Acclimation of a Central Neurone in Helix Aspersa: III. Ionic Substitution and Related Studies

1979 ◽  
Vol 78 (1) ◽  
pp. 201-211
Author(s):  
C. K. LANGLEY
Keyword(s):  
Chemical Composition ◽  
Electrical Properties ◽  
Membrane Resistance ◽  
Thermal Acclimation ◽  
Neuronal Membrane ◽  
Electrical Characteristics ◽  
Ionic Substitution ◽  
Warm Acclimation ◽  
Sodium And Potassium ◽  
Made In

(1) Thermal acclimation of the Fi neurone does not appear to result from changes in the chemical composition of the haemolymph. This is deduced from the lack of effect on the electrical characteristics of control neurones of either pooled haemolymph from acclimated individuals, or variations in the experimental salines made in accordance with haemolymph analyses. (2) Changes in [Ca]0 tended to act cooperatively with temperature shifts to induce alterations in the electrical properties of the neurone, notably to increase excitability and lower membrane resistance. (3) Warm acclimation was associated with increased resting conductance of the neuronal membrane to sodium and potassium, whereas chloride conductance appeared little affected.

Rhythmic hyperpolarizations and depolarization of sympathetic ganglion cells induced by caffeine

1976 ◽  
Vol 39 (3) ◽  
pp. 547-563 ◽  
Author(s):  
K. Kuba ◽  
S. Nishi
Keyword(s):  
Action Potential ◽  
Sympathetic Ganglion ◽  
External Medium ◽  
Ganglion Cells ◽  
Membrane Resistance ◽  
Free Medium ◽  
Dibutyryl Cyclic Amp ◽  
High K ◽  
Hyperpolarizing Response ◽  
K Permeability

Superfusion of the isolated sympathetic ganglion of the bullfrog with a caffeine-containing (1-6 mM) solution caused in many cells an initial slow hyperpolarization which was followed by a subliminal depolarization interruped by rhythmic hyperpolarizations. A hyperpolarization, similar to one of the rhythmic hyperpolarizations, could be triggered by an action potential in the presence of caffeine. The action potential itself was not markedly affected by caffeine except for its afterhyperpolarization which was prolonged. All these caffeine-induced hyperpolarizations were associated with a marked reduction of the membrane resistance, their amplitude was increased in a K+-free solution and decreased in a high-K+ solution, and their polarity was reversed at the same level at which the afterhyperpolarization was also inverted. This reversal level was not altered by omission of Na+ or C1- from the external medium. These hyperpolarizations were reversibly abolished by depletion of external Ca2+ or replacement of external Ca2+ by Mg2+. Excess of external Ca2+ caused a shortening of the interval between rhythmic hyperpolarizations. Furthermore, iontophoretic injection of EDTA into the cytoplasm markedly depressed the initial caffeine hyperpolarizatin and abolished both the rhythmic and evoked caffeine hyperpolarizations. The caffeine-induced depolarization was not affected by omission of external Cl-. It was decreased in a Na+-free medium, but completely eliminated by omission of both Na+ and Ca2+ from the external medium. Tetrodotoxin did not impair the production of the initial and the rhythmic hyperpolarizations. A strong depolarizing pulse could evoke a typical hyperpolarizing response in the presence of this compound. Dibutyryl cyclic AMP, d-tubocurarine, atropine, and phenoxybenzamine were without effect on the caffeine-induced hyperpolarizations and depolarization. It was concluded that each caffeine-induced hyperpolarization is the result of an increased K+ permeability, which is probably caused by a rise in the internal Ca2+ concentration. It was also concluded that the caffeine-induced depolarization is due to an increased membrane permeability to Ca2+ and Na+.

scholarly journals Electrical Properties and Acetylcholine Sensitivity of Singly and Multiply Innervated Avian Muscle Fibers

1969 ◽  
Vol 53 (5) ◽  
pp. 624-637 ◽  
Author(s):  
M. R. Fedde
Keyword(s):  
Electrical Properties ◽  
Latissimus Dorsi ◽  
Membrane Resistance ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Receptor Sites ◽  
Avian Muscle ◽  
Anterior Latissimus Dorsi ◽  
Length Constant ◽  
Low Sensitivity

Membrane constants and distribution of acetylcholine (ACh) receptors were determined for multiply innervated fibers of the anterior latissimus dorsi (ALD) and singly innervated fibers of the posterior latissimus dorsi (PLD) muscles of 3–6 month old chickens. The values of the various membrane constants were: length constant, 1.78 mm (mean) in ALD, 0.68 mm in PLD; time constant, 35 msec in ALD, 3.7 msec in PLD; transverse membrane resistance, 4388 Ω cm2 in ALD, 561 Ω cm2 in PLD; and membrane capacitance, 8.2 µF/cm2 in ALD, 7.0 µF/cm2 in PLD. Peaks of ACh sensitivity occurred at intervals of ca. 740 µ on ALD fibers with a low sensitivity remaining between peaks. Only one peak of ACh sensitivity was detected on PLD fibers. The maximum ACh sensitivity found was 5 ± 4 mv/ncoul for fibers of the ALD and 77 ± 60 mv/ncoul for fibers of the PLD. The distance over which this sensitivity fell to 0.1 was ca. 225 µ in the ALD and 140 µ in the PLD. The membranes of these two muscle fiber types differ widely regarding some electrical properties and the disposition of ACh-sensitive receptor sites.

Properties of thyroidectomized rat extensor muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C90-C95 ◽  
Author(s):  
J. Grossie
Keyword(s):  
Electrical Properties ◽  
Relaxation Times ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Extensor Muscle ◽  
Resting Membrane Potential ◽  
Rat Muscle ◽  
Mechanical And Electrical Properties ◽  
Isometric Twitch ◽  
Indirect Action

Basic mechanical and electrical properties of rat extensor muscle were analyzed 4--6 wk after thyroid removal. Isometric twitch tensions in thyroidectomized (Tx) rat muscle varied considerably, with over 60% of the muscles showing abnormally low values and the remainder showing a high twitch force. The duration of the twitch was significantly increased from 137 to 245 ms but contraction and half-relaxation times were not significantly changed. Tetanic force was not effected by thyroidectomy. Electrical properties of the muscle fiber membranes were made exclusively via intracellular techniques. The resting membrane potential was slightly higher in thyroidectomized rats (-79 mV) as compared to sham controls (-78 mV). Both direct and indirect action potentials showed higher overshoots, amplitudes, and rates of depolarization in thyroidectomized rats. The threshold of the indirect action potential appeared at a higher transmembrane potential as compared to sham-operated controls. The input resistance, space constant, time constant, and specific membrane resistance were all significantly increased in thyroidectomized rat extensor muscle, whereas fiber diameter and capacitance were significantly decreased. Estimates of specific ionic conductance show that both potassium and chloride conductance are decreased in thyroidectomized rat muscle.

scholarly journals Capacitance of the Surface and Transverse Tubular Membrane of Frog Sartorius Muscle Fibers

1969 ◽  
Vol 53 (3) ◽  
pp. 265-278 ◽  
Author(s):  
Peter W. Gage ◽  
Robert S. Eisenberg
Keyword(s):  
Electrical Properties ◽  
Time Course ◽  
Muscle Fibers ◽  
Membrane Resistance ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Tubular Membrane ◽  
Essentially Normal ◽  
The Difference ◽  
Passive Electrical Properties

The passive electrical properties of glycerol-treated muscle fibers, which have virtually no transverse tubules, were determined. Current was passed through one intracellular microelectrode and the time course and spatial distribution of the resulting potential displacement measured with another. The results were analyzed by using conventional cable equations. The membrane resistance of fibers without tubules was 3759 ± 331 ohm-cm2 and the internal resistivity 192 ohm-cm. Both these figures are essentially the same as those found in normal muscle fibers. The capacitance of the fibers without tubules is strikingly smaller than normal, being 2.24 ± 0.14 µF/cm2. Measurements were also made of the passive electrical properties of fibers in a Ringer solution containing 400 mM glycerol (which is used in the preparation of glycerol-treated fibers). The membrane resistance and capacitance are essentially normal, but the internal resistivity is somewhat reduced. These results show that glycerol in this concentration does not directly affect the membrane capacitance. Thus, the figure for the capacitance of glycerol-treated fibers, which agrees well with previous estimates made by different techniques, represents the capacitance of the outer membrane of the fiber. Estimates of the capacitance per unit area of the tubular membrane are made and the significance of the difference between the figures for the capacitance of the surface and tubular membrane is discussed.

Factors influencing transepithelial potential difference in mammalian distal tubule

1978 ◽  
Vol 234 (3) ◽  
pp. F182-F191 ◽  
Author(s):  
J. P. Hayslett ◽  
E. L. Boulpaep ◽  
G. H. Giebisch
Keyword(s):  
Electrical Properties ◽  
Cell Membrane ◽  
Distal Tubule ◽  
Potential Difference ◽  
Ion Concentration ◽  
Luminal Cell ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference ◽  
Factors Influencing ◽  
Average Slope

Studies were performed to examine some electrical properties of the mammalian distal tubule. Experiments were performed to evaluate the influence of changes in ion concentration in luminal fluid on transepithelial potential difference. Variations in the concentration of Na+ and K+, near the physiologic range, resulted in only modest changes in potential difference. During changes in Na+ the average slope, deltaV/ln C2/C1, was -1.52 +/- 0.39 mV and during variations in K+ the slope was -5.60 +/- 0.95 mV. Changes in Cl- concentration had no effect on transepithelial potential difference. Since the sum of transferase numbers did not equal 1, it seems likely that potential difference is influenced by a shunt current due to cellular rheogenic pumps. These data, therefore, indicate that variations in ion concentration in tubular fluid of the mammalian distal tubule do not significantly influence the resting transepithelial potential difference, and they suggest that analysis of permselective properties of the luminal cell membrane by transepithelial electrophysiologic approaches is probably invalid.

scholarly journals Ionic Relations of Cells of Ohara Australis VII. The Separate Electrical Oharacteristics of the Plasmalemma and Tonoplast

1964 ◽  
Vol 17 (1) ◽  
pp. 62 ◽  
Author(s):  
GP Findlay ◽  
AB Hope
Keyword(s):  
Electrical Properties ◽  
Ionic Relations

A study of the electrical properties of tho two membranes bounding the cytoplasm in almra cells was made. Three electrodes were employed: a metal probe to pass current, inserted longitudinally into the vacuole, and two glass microelectrodes, to measure potential differences, inserted into the vacuole and cytoplasm.

scholarly journals Comparison of the Values of Solar Cell Contact Resistivity Measured with the Transmission Line Method (TLM) and the Potential Difference (PD)

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5590
Author(s):  
Małgorzata Musztyfaga-Staszuk
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Electrical Properties ◽  
Transmission Line ◽  
Contact Resistivity ◽  
Potential Difference ◽  
Firing Process ◽  
Measuring Instruments ◽  
Cell Contact ◽  
Cell Parameters

This work presents a comparison of values of the contact resistivity of silicon solar cells obtained using the following methods: the transmission line model method (TLM) and the potential difference method (PD). Investigations were performed with two independent scientific units. The samples were manufactured with silver front electrodes. The co-firing process was performed in an infrared belt furnace in a temperature range of 840 to 960 °C. The electrical properties of a batch of solar cells fabricated in two cycles were investigated. This work focuses on the different metallisation temperatures of co-firing solar cells and measurements were carried out using the methods mentioned. In the TLM and PD methods, the same calculation formulae were used. Moreover, solar cell parameters measured with these methods had the same, similar, or sometimes different but strongly correlated values. Based on an analysis of the selected databases, this article diagnoses the recent and current state of knowledge regarding the employment of the TLM and PD methods and the available hardware base. These methods are of interest to various research centres, groups of specialists dealing with the optimisation of the electrical properties of silicon photovoltaic cells, and designers of measuring instruments.

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