scholarly journals S-Potentials in the Skate Retina

1971 ◽  
Vol 58 (2) ◽  
pp. 163-189 ◽  
Author(s):  
John E. Dowling ◽  
Harris Ripps
Keyword(s):  
Membrane Potential ◽  
Ganglion Cell ◽  
Dark Adaptation ◽  
Membrane Potentials ◽  
Horizontal Cells ◽  
Photic Stimulation ◽  
Visual Adaptation ◽  
Cell Discharge ◽  
Background Fields ◽  
Potential Level

The S-potentials recorded intracellularly from the all-rod retina of the skate probably arise from the large horizontal cells situated directly below the layer of receptors. These cells hyperpolarize in response to light, irrespective of stimulus wavelength, and the responses in photopic as well as scotopic conditions were found to be subserved by a single photopigment with λmax = 500 nm. The process of adaptation was studied by recording simultaneously the threshold responses and membrane potentials of S-units during both light and dark adaptation. The findings indicate that the sensitivity of S-units, whether measured upon steady background fields or in the course of dark adaptation, exhibits changes similar to those demonstrated previously for the ERG b-wave and ganglion cell discharge. However, the membrane potential level of the S-unit and its sensitivity to photic stimulation varied independently for all the adapting conditions tested. It appears, therefore, that visual adaptation in the skate retina occurs before the S-unit is reached, i.e., at the receptors themselves.

scholarly journals Retinal mechanisms of visual adaptation in the skate.

1975 ◽  
Vol 65 (4) ◽  
pp. 483-502 ◽  
Author(s):  
D G Green ◽  
J E Dowling ◽  
I M Siegel ◽  
H Ripps
Keyword(s):  
Ganglion Cell ◽  
Cell Activity ◽  
Receptor Potential ◽  
Visual Adaptation ◽  
Cell Discharge ◽  
Cell Responses ◽  
Electrical Potentials ◽  
Rate Of Recovery ◽  
Network Mechanism ◽  
Different Levels

Electrical potentials were recorded from different levels within the skate retina. Comparing the adaptive properties of the various responses revealed that the isolated receptor potential and the S-potential always exhibited similar changes in sensitivity, and that the b-wave and ganglion-cell thresholds acted in concert. However, the two sets of responses behaved differently under certain conditions. For example, a dimly iluminated background that had no measurable effect on the senitivities of either of the distal responses, raised significantly the thresholds of both the b-wave and the ganglion cell responses. In addition, the rate of recovery during the early, "neural" phase of dark adaptation was significantly faster for the receptor and S-potentials than for the b-wave or ganglion cell discharge. These results indicate that there is an adaptive ("network") mechanism in the retina which can influence significantly b-wave and gaglion cell activity and which behaves independently of the receptors and horizontal cells. We conclude that visual adaptation in the skate retina is regulated by a combination of receptoral and network mechanisms.

NADPH diaphorase activity in mammalian retinas is modulated by the state of visual adaptation

1996 ◽  
Vol 13 (5) ◽  
pp. 863-871 ◽  
Author(s):  
Esther Zemel ◽  
Orly Eyal ◽  
Bo Lei ◽  
Ido Perlman
Keyword(s):  
Nitric Oxide ◽  
Dark Adaptation ◽  
Physiological Role ◽  
Müller Cells ◽  
Amacrine Cells ◽  
The State ◽  
Nadph Diaphorase ◽  
Horizontal Cells ◽  
Visual Adaptation ◽  
Diaphorase Activity

AbstractNADPH diaphorase histochemistry is commonly used to identify cells containing nitric oxide synthase (NOS), the enzyme catalyzing the production of nitric oxide from L-arginine. NADPH diaphorase activity and NOS immunostaining was demonstrated in different cells of the vertebrate retina; photoreceptors, horizontal cells, amacrine cells, ganglion cells, and Müller cells. However, the physiological role of nitric oxide (NO) in the retina has yet to be elucidated. In this study, we tested the assumption that NADPH diaphorase activity in the retinas of rabbits and rats depended on the state of visual adaptation. In the rabbit, light adaptation enhanced NADPH diaphorase activity in amacrine cells and practically eliminated it in horizontal cells. Dark adaptation induced the opposite effects; the NADPH diaphorase activity was reduced in amacrine cells and enhanced in horizontal cells. Retinas from eyes that were injected intravitreally with L-glutamate exhibited a pattern of NADPH diaphorase activity that was similar to that seen in dark-adapted retinas. In rats, the NADPH diaphorase activity of amacrine and horizontal cells exhibited adaptation dependency similar to that of the rabbit retina. But, the most pronounced effect of dark adaptation in the rat's retina was an enhancement of NADPH diaphorase activity in Müller cells, especially of the endfoot region. Assuming that NADPH diaphorase activity is a marker for NOS, these findings suggest that NO production in the mammalian retina is modulated by the level of ambient illumination and support the notion that NO plays a physiological role in the retina.

scholarly journals Adaptation in Skate Photoreceptors

1972 ◽  
Vol 60 (6) ◽  
pp. 698-719 ◽  
Author(s):  
John E. Dowling ◽  
Harris Ripps
Keyword(s):  
Dark Adaptation ◽  
Control Mechanism ◽  
Pigment Epithelium ◽  
Gain Control ◽  
Receptor Potential ◽  
Recovery Phase ◽  
Cell Discharge ◽  
Receptor Response ◽  
Full Complement ◽  
Background Fields

Receptor potentials were recorded extracellularly from the all-rod retina of the skate after the application of sodium aspartate. This agent suppresses the responses of proximal elements, but leaves relatively unaffected the electrical activity of the photoreceptors (a-wave) and pigment epithelium (c-wave). Since the latter develops too slowly to interfere with the receptor response, it was possible to isolate receptor potentials and to compare their behavior in light and dark adaptation with earlier observations on the S-potential, b-wave, and ganglion cell discharge. The results show that the photoreceptors display the full complement of adaptational changes exhibited by cells proximal to the receptors. Thus, it appears that visual adaptation in the skate is governed primarily by the photoreceptors themselves. Of particular interest was the recovery of sensitivity in the presence of background fields that initially saturate the receptor potential. Analysis of this recovery phase indicates that a gain-control mechanism operates within the receptors, at a distal stage of the visual process.

scholarly journals On the Wireless Microwave Sensing of Bacterial Membrane Potential in Microfluidic-Actuated Platforms

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3420
Author(s):  
Marc Jofre ◽  
Lluís Jofre ◽  
Luis Jofre-Roca
Keyword(s):  
Membrane Potential ◽  
Living Cells ◽  
Membrane Potentials ◽  
Electromagnetic Properties ◽  
Bacterial Membrane ◽  
Microfluidic Platforms ◽  
Bacterial Membranes ◽  
Wireless Monitoring ◽  
Bacterial Dynamics ◽  
Engineered Systems

The investigation of the electromagnetic properties of biological particles in microfluidic platforms may enable microwave wireless monitoring and interaction with the functional activity of microorganisms. Of high relevance are the action and membrane potentials as they are some of the most important parameters of living cells. In particular, the complex mechanisms of a cell’s action potential are comparable to the dynamics of bacterial membranes, and consequently focusing on the latter provides a simplified framework for advancing the current techniques and knowledge of general bacterial dynamics. In this work, we provide a theoretical analysis and experimental results on the microwave detection of microorganisms within a microfluidic-based platform for sensing the membrane potential of bacteria. The results further advance the state of microwave bacteria sensing and microfluidic control and their implications for measuring and interacting with cells and their membrane potentials, which is of great importance for developing new biotechnologically engineered systems and solutions.

scholarly journals Intracellular recordings from gecko photoreceptors during light and dark adaptation.

1975 ◽  
Vol 66 (5) ◽  
pp. 617-648 ◽  
Author(s):  
J Kleinschmidt ◽  
J E Dowling
Keyword(s):  
Membrane Potential ◽  
Dark Adaptation ◽  
Horizontal Cell ◽  
Intracellular Recordings ◽  
Receptor Sensitivity ◽  
Intensity Curve ◽  
Voltage Range ◽  
Voltage Change ◽  
Sensitivity Change ◽  
Compression Treatment

Intracellular recordings were obtained from rods in the Gekko gekko retina and the adaptation characteristics of their responses studied during light and dark adaptation. Steady background illumination induced graded and sustained hyperpolarizing potentials and compressed the incremental voltage range of the receptor. Steady backgrounds also shifted the receptor's voltage-intensity curve along the intensity axis, and bright backgrounds lowered the saturation potential of the receptor. Increment thresholds of single receptors followed Weber's law over a range of about 3.5 log units and then saturated. Most of the receptor sensitivity change in light derived from the shift of the voltage-intensity curve, only little from the voltage compression. Treatment of the eyecup with sodium aspartate at concentrations sufficient to eliminate the beta-wave of the electroretinogram (ERG) abolished initial transients in the receptor response, possibly indicating the removal of horizontal cell feedback. Aspartate treatment, however, did not significantly alter the adaptation characteristics of receptor responses, indicating that they derive from processes intrinsic to the receptors. Dark adaptation after a strongly adapting stimulus was similarly associated with temporary elevation of membrane potential, initial lowering of the saturation potential, and shift of the voltage-intensity curve. Under all conditions of adaptation studied, small amplitude responses were linear with light intensity. Further, there was no unique relation between sensitivity and membrane potential suggesting that receptor sensitivity is controlled at least in part by a step of visual transduction preceding the generation of membrane voltage change.

The Retina of Asian and African Elephants: Comparison of Newborn and Adult

2017 ◽  
Vol 89 (2) ◽  
pp. 84-103 ◽  
Author(s):  
Heidrun Kuhrt ◽  
Andreas Bringmann ◽  
Wolfgang Härtig ◽  
Gudrun Wibbelt ◽  
Leo Peichl ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Ganglion Cell ◽  
Glial Cells ◽  
Ganglion Cells ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
Retinal Ganglion ◽  
Terrestrial Mammals ◽  
Contrast Perception ◽  
First Time

Elephants are precocial mammals that are relatively mature as newborns and mobile shortly after birth. To determine whether the retina of newborn elephants is capable of supporting the mobility of elephant calves, we compared the retinal structures of 2 newborn elephants (1 African and 1 Asian) and 2 adult animals of both species by immunohistochemical and morphometric methods. For the first time, we present here a comprehensive qualitative and quantitative characterization of the cellular composition of the newborn and the adult retinas of 2 elephant species. We found that the retina of elephants is relatively mature at birth. All retinal layers were well discernible, and various retinal cell types were detected in the newborns, including Müller glial cells (expressing glutamine synthetase and cellular retinal binding protein; CRALBP), cone photoreceptors (expressing S-opsin or M/L-opsin), protein kinase Cα-expressing bipolar cells, tyrosine hydroxylase-, choline acetyltransferase (ChAT)-, calbindin-, and calretinin-expressing amacrine cells, and calbindin-expressing horizontal cells. The retina of newborn elephants contains discrete horizontal cells which coexpress ChAT, calbindin, and calretinin. While the overall structure of the retina is very similar between newborn and adult elephants, various parameters change after birth. The postnatal thickening of the retinal ganglion cell axons and the increase in ganglion cell soma size are explained by the increase in body size after birth, and the decreases in the densities of neuronal and glial cells are explained by the postnatal expansion of the retinal surface area. The expression of glutamine synthetase and CRALBP in the Müller cells of newborn elephants suggests that the cells are already capable of supporting the activities of photoreceptors and neurons. As a peculiarity, the elephant retina contains both normally located and displaced giant ganglion cells, with single cells reaching a diameter of more than 50 µm in adults and therefore being almost in the range of giant retinal ganglion cells found in aquatic mammals. Some of these ganglion cells are displaced into the inner nuclear layer, a unique feature of terrestrial mammals. For the first time, we describe here the occurrence of many bistratified rod bipolar cells in the elephant retina. These bistratified bipolar cells may improve nocturnal contrast perception in elephants given their arrhythmic lifestyle.

Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes

2007 ◽  
Vol 292 (1) ◽  
pp. R388-R395 ◽  
Author(s):  
Cristina E. Molina ◽  
Hans Gesser ◽  
Anna Llach ◽  
Lluis Tort ◽  
Leif Hove-Madsen
Keyword(s):  
Membrane Potential ◽  
Action Potential ◽  
Ventricular Myocytes ◽  
Reversal Potential ◽  
Membrane Potentials ◽  
Resting Membrane Potential ◽  
Atrial Myocytes ◽  
Atrial Tissue ◽  
Isolated Cardiac Myocytes ◽  
Inwardly Rectifying

Application of the current-clamp technique in rainbow trout atrial myocytes has yielded resting membrane potentials that are incompatible with normal atrial function. To investigate this paradox, we recorded the whole membrane current ( Im) and compared membrane potentials recorded in isolated cardiac myocytes and multicellular preparations. Atrial tissue and ventricular myocytes had stable resting potentials of −87 ± 2 mV and −83.9 ± 0.4 mV, respectively. In contrast, 50 out of 59 atrial myocytes had unstable depolarized membrane potentials that were sensitive to the holding current. We hypothesized that this is at least partly due to a small slope conductance of Im around the resting membrane potential in atrial myocytes. In accordance with this hypothesis, the slope conductance of Im was about sevenfold smaller in atrial than in ventricular myocytes. Interestingly, ACh increased Im at −120 mV from 4.3 pA/pF to 27 pA/pF with an EC50 of 45 nM in atrial myocytes. Moreover, 3 nM ACh increased the slope conductance of Im fourfold, shifted its reversal potential from −78 ± 3 to −84 ± 3 mV, and stabilized the resting membrane potential at −92 ± 4 mV. ACh also shortened the action potential in both atrial myocytes and tissue, and this effect was antagonized by atropine. When applied alone, atropine prolonged the action potential in atrial tissue but had no effect on membrane potential, action potential, or Im in isolated atrial myocytes. This suggests that ACh-mediated activation of an inwardly rectifying K+ current can modulate the membrane potential in the trout atrial myocytes and stabilize the resting membrane potential.

scholarly journals Method of Determining Seed Germination by Using Membrane Potential of Wheat Seeds

2019 ◽  
Vol 29 (3) ◽  
pp. 443-455 ◽  
Author(s):  
Nadezhda N. Barysheva ◽  
Sergey P. Pronin
Keyword(s):  
Membrane Potential ◽  
Rapid Assessment ◽  
Membrane Potentials ◽  
Seeding Rate ◽  
Important Indicator ◽  
Agricultural Enterprises ◽  
Highly Sensitive ◽  
Technological Stage ◽  
Seeds Germination ◽  
Wheat Seeds

Introduction. The germination of wheat seeds is an important indicator of their quality, used to calculate and adjust the seeding rate. It is necessary to take into account germination changes at the storage stage. The solution of this problem will be development of a method that will allow to determinate germination at any technological stage (at the stage of harvesting, storage, seeding).The aim of the article is to study the dependence of membrane potential on grain quality, to develop a method for determining the germination of wheat seeds based on their membrane potentials. Materials and Methods. The authors' review of research papers about methods of assessing the wheat seeds quality indicates the need for the development of highly sensitive methods of the germination test, which allow one to ensure the speed of measurement and obtain more accurate results for further use. An approach was developed on the basis of the review, which allows for solving the problem using the method based on the study of membrane potentials of wheat seeds. Results. In this article, the study of the dependence of wheat seeds membrane potential from their germination was conducted. The results of experiments confirmed that the value of the potential could be used as quality assessment parameter. The requirements and optimal conditions for conducting the experiment were determined. Discussion and Conclusion. The dependence of the wheat seeds membrane potential on their germination was established and the method for determining wheat seeds germination was developed. The implementation of this method will allow agricultural enterprises and farms to carry out the rapid assessment of wheat seeds germination at any technological stage (at the stage of harvesting, storage, seeding).

Membrane Potentials in Amoeba Proteus

1966 ◽  
Vol 45 (2) ◽  
pp. 251-267
Author(s):  
M. S. BINGLEY
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Morphological Changes ◽  
Amoeba Proteus ◽  
Membrane Potentials ◽  
The Other ◽  
The Earth ◽  
Electrode Resistance ◽  
Alternating Voltage

1. Amoebae can be penetrated by microelectrodes at either end. One records voltage and the other supplies alternating current. 2. Step-like increases in alternating voltage superimposed on potentials recorded by the voltage electrode when in either the pseudopod or rear region demonstrate that low potentials recorded from a pseudopod and high ones from the rear region exist across a discrete impedance barrier. The only structure so far shown to fulfil this function is the plasma membrane. 3. A resistance inserted in the earth path monitors current flowing through the system and confirms observations made when recording with single electrodes that there is a reduction of electrode resistance when the cell is entered. 4. Pronounced depolarization in the rear region is shown when the current-carrying electrode penetrates the pseudopod, but not vice versa. 5. Morphological changes associated with membrane potential reversal are illustrated. 6. Consideration is given to the role of step-like potential changes in movement.

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