scholarly journals Neurons, potassium, and glia in proximal retina of Necturus.

1980 ◽  
Vol 75 (2) ◽  
pp. 141-162 ◽  
Author(s):  
C J Karwoski ◽  
L M Proenza
Keyword(s):  
Time Course ◽  
Primary Source ◽  
Amacrine Cells ◽  
Müller Cell ◽  
Wave Form ◽  
Cell Responses ◽  
Decay Times ◽  
Low Pass ◽  
Muller Cell ◽  
Time Courses

Light-evoked K+ flux and intracellular Müller (glial) cell and on/off-neuron responses were recorded from the proximal retina of Necturus in eyecups from which the vitreous was not drained. On/off-responses, probably arising from amacrine cells, showed an initial transient and a sustained component that always exhibited surround antagonism. Müller cell responses were small but otherwise similar to those recorded in eyecups drained of vitreous. The proximal K+ increase and Müller cell responses had identical decay times, and on some occasions the latency and rise time of the K+ increase nearly matched Müller cell responses, indicating that the recorded K+ responses were not always appreciably degraded by electrode "dead space." The spatiotemporal distribution of the K+ increase showed that both diffusion and active reuptake play important roles in K+ clearance. The relationship between on/off-neuron responses and the K+ increase was modelled by assuming that (a) K+ release is positively related to the instantaneous amplitude of the neural response, and (b) K+ accumulating in extracellular space is cleared via mechanisms with approximately exponential time-courses. These two processes were approximated by low-pass filtering the on/off-neuron responses, resulting in modelled responses that match the wave form and time-course of the K+ increase and behave quantitatively like the K+ increase to changes in stimulus intensity and diameter. Thus, on/off-neurons are probably a primary source of the proximal light-evoked K+ increase that depolarizes glial cells to generate the M-wave.

PII component of the toad electroretinogram

1992 ◽  
Vol 68 (1) ◽  
pp. 333-341 ◽  
Author(s):  
B. J. Katz ◽  
Z. Xu ◽  
J. Zheng ◽  
B. Oakley
Keyword(s):  
Excitatory Amino Acid ◽  
Cell Activity ◽  
Plexiform Layer ◽  
Müller Cell ◽  
Light Responses ◽  
M Wave ◽  
Cell Responses ◽  
Ion Sensitive Microelectrodes ◽  
Muller Cell ◽  
Dc Component

1. The PII component of the electroretinogram (ERG) is comprised of the b-wave and the DC component and is thought to reflect bipolar cell activity. Although the b-wave is generated in large part by a K+/Muller cell mechanism, the origin of the DC component is unclear. In this paper we detail our investigation of the origin of the DC component. We hypothesize that the DC component is generated by a K+/Muller cell mechanism identical to that involved in b-wave generation. 2. We studied the ERG in the dark-adapted, isolated retina preparation of the toad, Bu fo marinus. We used K+ ion-sensitive microelectrodes (K+ISM), as well as conventional intra- and extracellular microelectrodes, to record [K+]o changes, the vitreal ERG, and Muller cell responses. 3. We used the excitatory amino acid receptor agonist N-methyl-DL-aspartate (NMDLA) to inhibit light responses of third-order neurons and thereby eliminate most of the ERG M-wave. In the absence of the M-wave, the ERG consisted of PII and PIII. We then superfused the retina with a solution containing both kynurenic acid (KYN) and 2-amino-4-phosphonobutyric acid (APB), which together inhibit all retinal responses proximal to the photoreceptors. In the presence of KYN and APB, the ERG consisted only of PIII. Using digital subtraction, we reconstructed PII. To our knowledge, this is the first report of the isolation of a PII component in the ERG of a nonmammalian species. 4. Using K+ISMs, we recorded the distal K+ changes in the outer plexiform layer (OPL).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Adaptive Müller cell responses to microglial activation mediate neuroprotection and coordinate inflammation in the retina

2011 ◽  
Vol 8 (1) ◽  
pp. 173 ◽  
Author(s):  
Minhua Wang ◽  
Wenxin Ma ◽  
Lian Zhao ◽  
Robert N Fariss ◽  
Wai T Wong
Keyword(s):  
Microglial Activation ◽  
Müller Cell ◽  
Cell Responses ◽  
Muller Cell

First Responders: Dynamics of Pre-Gliotic Müller Cell Responses in The Isolated Adult Rat Retina

2014 ◽  
Vol 40 (12) ◽  
pp. 1245-1260 ◽  
Author(s):  
Linnéa Taylor ◽  
Karin Arnér ◽  
Fredrik Ghosh
Keyword(s):  
First Responders ◽  
Müller Cell ◽  
Rat Retina ◽  
Adult Rat ◽  
Cell Responses ◽  
Muller Cell

Relationship between Muller cell responses, a local transretinal potential, and potassium flux

1977 ◽  
Vol 40 (2) ◽  
pp. 244-259 ◽  
Author(s):  
C. J. Karowski ◽  
L. M. Proenza
Keyword(s):  
Müller Cells ◽  
Müller Cell ◽  
Extracellular Potassium ◽  
Muller Cells ◽  
Light Onset ◽  
M Wave ◽  
Cell Responses ◽  
Stimulus Parameters ◽  
Muller Cell ◽  
Cell Depolarization

1. In the Necturus retina, light-evoked field potentials, Muller (glial) cell responses, and extracellular potassium ion concentration ([K+]0) were recorded and found to exhibit the three-way correlation characteristic of these variables elsewhere in the nervous system. 2. Muller cell responses to a flashed spot or annulus consist primarily of slow depolarizations at both light onset and offset. The responses are maximum to 0.5-mm-diameter spots and decrease with larger diameters. Responses to stimulus intensity and flicker were also used to characterize Muller cell behavior. 3. In response to long-duration stimuli, the initial Muller cell depolarization is followed by a very slow hyperpolarization, which is likely the origin of slow PIII. 4. A new extracellular potential is described, the M-wave, the basic properties of which suggest that it is generated by Muller cells. Moreover, the M-wave and Muller cells show remarkably similar behavior to a wide variety of stimulus parameters. 5. In the proximal retina, [K+]0 increases at both light onset and offset with a time course similar to that of Muller cell depolarizing responses. This K+ increase also behaves similarly to the Muller cell depolarization in response to changes in stimulus parameters. 6. It is concluded that light stimulation leads to an increase in [K+]0 in the proximal retina and that this increase depolarizes Muller cells whose associated currents, in turn, generate the M-wave.

Effects of multiple doses of organophosphates on evoked potentials in mouse diaphragm

1997 ◽  
Vol 16 (2) ◽  
pp. 72-78 ◽  
Author(s):  
Sean S Kelly ◽  
Gail E de Blaquière ◽  
Faith M Williams ◽  
Peter G Blain
Keyword(s):  
Time Course ◽  
Diaphragm Muscle ◽  
Neuropathy Target Esterase ◽  
Multiple Dosing ◽  
Post Dose ◽  
Endplate Potential ◽  
Multiple Doses ◽  
Decay Times ◽  
Time Courses ◽  
Endplate Potentials

1 Male albino mice were injected s.c. with an organopho sphate (mipafox, ecothiopate or paraoxon). Treat ments were either a single injection or multiple daily injections with lower doses for 5 or 8 days. At 3 h after injection the activity of brain and diaphragm acet ylcholinesterase and of brain neuropathy target esterase (NTE) was measured. Also measured in the diaphragm at 3 h post dose was the duration of spontaneous miniature endplate potentials (eMEPPs), recorded extracellularly. 2 At 7 and 28 days after dosing action potentials and evoked endplate potentials, produced by stimulating the phrenic nerve at 30 Hz, were recorded in diaphragm muscle. The amplitudes, time-course and latencies of these potentials were measured and the variability of latencies (jitter) was calculated. 3 Single doses of mipafox (20 mg/kg), ecothiopate (0.192 mg/kg) or paraoxon (0.415 mg/kg) in the mouse produced ca. 70% inhibition of diaphragm acetylcho linesterase at 3 h after dosing. All three OPs produced a prolongation of the half-decay times of eMEPPs. 4 All three OPs in the above single doses produced increased muscle action potential (postjunctional) jitter but only mipafox produced an increase in endplate potential (prejunctional) jitter. Mipafox in a slightly reduced single dose (17.5 mg/kg) had no effect on prejunctional or postjunctional jitter. 5 Multiple dosing with mipafox (8 mg/kg daily for 5 days) increased both postjunctional and prejunctional jitter at both 7 and 28 days after the end of dosing. After multiple dosing with mipafox (5 mg/kg daily for 5 days) postjunctional (but not prejunctional) jitter was increased. Multiple doses of paraoxon (0.166 mg/kg daily for 5 days) or ecothiopate (0.76 mg/kg daily for 5 days) increased prejunctional and postjunctional jitter. 6 Depending on the dosing regime, all three OPs tested were capable of increasing both prejunctional and postjunctional jitter. Neither ecothiopate nor paraox on inhibited NTE, so this prejunctional effect is not likely to be related to 'classical' OP-induced delayed neuropathy. The prejunctional effects may be related to long-term inhibition of acetylcholinesterase and the triggering mechanism for increase in prejunctional jitter may involve a relationship between the inhibi tion of acetylcholinesterase and the time for which it is inhibited. The differences between the time-courses of increases in prejunctional and postjunctional jitter and the differential effects of the different multiple dosing regimes indicate that it is likely that the triggering relationship between enzyme inhibition and time is different for prejunctional and postjunc tional effects.

Relationships between Müller cells and neurons in a primitive tetrapod, the Australian lungfish

1997 ◽  
Vol 14 (4) ◽  
pp. 795-800 ◽  
Author(s):  
Stephen R. Robinson
Keyword(s):  
Ganglion Cells ◽  
Horizontal Cell ◽  
Müller Cells ◽  
Amacrine Cells ◽  
Müller Cell ◽  
Muller Cells ◽  
Cone Photoreceptors ◽  
Rod Photoreceptors ◽  
Muller Cell ◽  
Australian Lungfish

AbstractWe recently proposed a model of cytogenesis which assumes that primitive ancestral mammals and premammalian vertebrates had a retinal composition that consisted of about seven neurons per Müller cell, comprising 1–2 cone photoreceptors, 1–2 rod photoreceptors, 2–3 bipolar cells, 1–2 amacrine cells, less than 1 ganglion cell, and less than 1 horizontal cell (Reichenbach & Robinson, 1995). The Australian lungfish (Neoceratodus forsten) closely resembles the lobe-finned ancestors of land vertebrates, and has an extremely plesiomorphic nervous system. The present study, therefore, has examined the relative frequencies of retinal neurons and Müller cells (identified by immunolabelling for glutamine synthetase) in the lungfish retina. It was found that for each Müller cell there is an average of 1.9 cone photoreceptors, 1.7 rod photoreceptors, 3.1 amacrine/bipolar/horizontal cells, and 0.6 ganglion cells; amounting to a ratio of 7.3 neurons per Müller cell. These results support our conjecture that the sequence of cytogenesis in mammals is constrained by a developmental program that predates the evolution of mammals. The study also provides the first detailed morphological descriptions of lungfish Müller cells and their relationship with adjacent neurons. It was found that individual Müller cells in lungfish have a volume (more than 12,000 μm3) that is an order of magnitude higher than in mammals, yet the proportion of total retinal volume occupied by these cells (20%) is very similar.

scholarly journals Early Receptor Potentials of Rods and Cones in Rodents

1966 ◽  
Vol 49 (6) ◽  
pp. 1199-1208 ◽  
Author(s):  
WILLIAM L. PAK ◽  
THOMAS G. EBREY
Keyword(s):  
Time Course ◽  
Light Adaptation ◽  
Receptor Potential ◽  
Ground Squirrels ◽  
Wave Form ◽  
Second Phase ◽  
Response Curves ◽  
Early Receptor Potential ◽  
Time Courses ◽  
Cone Potential

The second phase (negative peak) of the early receptor potential of cones has been studied in the all-cone eyes of the Mexican and antelope ground squirrels (Citellus mexicanus and Citellus leucurus) and compared with responses from the rod-dominant eyes of the rat and flying squirrel (Glaucomys volans). The responses obtained from the all-cone eyes tended to be smaller in amplitude, to have higher thresholds, and to be considerably more resistant to light adaptation than the responses from the rod-dominant eyes. The wave forms and time courses of the two types of responses were similar, although the cone potential tended to be less sensitive to temperature variations and its time constants tended to be shorter than those of the rod potential. The spectral sensitivity of the second phase of the early receptor potential of the Mexican ground squirrel closely follows the absorption spectrum of a Dartnall nomogram pigment having its absorption maximum at 540 mμ. Moreover, as in the case of the rat, the amplitude of the response appears to be linearly related to the amount of pigment bleached in a flash. Thus, in both all-rod and all-cone systems the early receptor potential appears to arise in the photoexcitation of the respective visual pigment and appears to be closely linked to the initial photochemical events. The similarity of the wave form, time course, and stimulus-response curves in the two systems suggests that the early receptor potential is produced by similar mechanisms in all-rod and all-cone systems.

Cellular Organization in Retinal Transplants Using Cell Suspensions or Fragments of Embryonic Retinal Tissue

1993 ◽  
Vol 2 (5) ◽  
pp. 411-418 ◽  
Author(s):  
Bengt Juliusson ◽  
Anders Bergström ◽  
Theo Van Veen ◽  
Berndt Ehinger
Keyword(s):  
Cell Suspension ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Cell Suspensions ◽  
Müller Cell ◽  
Immunocytochemical Staining ◽  
Inner Plexiform Layer ◽  
Cellular Organization ◽  
Muller Cell ◽  
Retinal Transplants

We have investigated the cellular organization in two different types of retinal transplants using cell type-specific monoclonal antibodies. Both fragments and cell suspensions of E17-E19 Sprague–Dawley rat retina were transplanted to a subretinal site in congenic adult rat hosts. After a survival time of 28 days, the transplants were stained by immunocytochemistry with antibodies against rhodopsin, which stained rods; with antibodies against HPC-1, which stained amacrine cells and outer and inner plexiform layers; and with antibodies against vimentin, which stained Müller cell fibers and horizontal cells. In the host retina, the distribution of immunocytochemical staining was similar, irrespective of transplantation technique. In the transplants, the antirhodopsin staining showed that fragment transplants developed photoreceptors in rosettes, whereas in cell suspension transplants, this staining showed a scattered distribution of photoreceptors. The HPC-1 staining showed that regions corresponding to the inner nuclear layer surrounded both types of transplants and made large invaginations into them. In one case, using the cell suspension technique, fibres were found to run from the inner plexiform layer of the transplant to the outer plexiform layer of the host. The vimentin staining revealed a disorganized array of Müller cell fibres in both types of transplants, but with some concentration to the regions corresponding to the inner plexiform layer.

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