Flash Responses of Mouse Rod Photoreceptors in the Isolated Retina and Corneal Electroretinogram: Comparison of Gain and Kinetics

We have measured the sensitivity of rod photoreceptors isolated from overnight dark–adapted mice of age P12 (neonate) through P45 (adult) with suction-pipette recording. During this age period, the dark current increased roughly in direct proportion to the length of the rod outer segment. In the same period, the flash sensitivity of rods (reciprocal of the half-saturating flash intensity) increased by ∼1.5-fold. This slight developmental change in sensitivity was not accentuated by dark adapting the animal for just 1 h or by increasing the ambient luminance by sixfold during the prior light exposure. The same small, age-dependent change in rod sensitivity was found with rat. After preincubation of the isolated retina with 9-cis-retinal, neonatal mouse rods showed the same sensitivity as adult rods, suggesting the presence of a small amount of free opsin being responsible for their lower sensitivity. The sensitivity of neonate rods could also be increased to the adult level by dark adapting the animal continuously for several days. By comparing the sensitivity of neonate rods in darkness to that of adult rods after light bleaches, we estimated that ∼1% of rod opsin in neonatal mouse was devoid of chromophore even after overnight dark adaptation. Overall, we were unable to confirm a previous report that a 50-fold difference in rod sensitivity existed between neonatal and adult rats.

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Measurement of potassium turnover in rod photoreceptors in toad isolated retina using ion-selective microelectrodes

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y87-161 ◽

1987 ◽

Vol 65 (5) ◽

pp. 1018-1027 ◽

Cited By ~ 3

Author(s):

Burks Oakley II

Keyword(s):

Cell Types ◽

Bufo Marinus ◽

Background Illumination ◽

Rod Photoreceptors ◽

Isolated Retina ◽

Small Change ◽

Toad Bufo

Ion-selective microelectrodes (ISMs) were used to measure the turnover of intracellular K+[Formula: see text] in rods in the isolated retina of the toad, Bufo marinus. The light-evoked hyperpolarization of rods decreases their passive K+ efflux, which in combination with active K+ uptake, decreases extracellular K+ concentration, [Formula: see text]. Rb+ substitutes for K+ in these processes. The turnover of [Formula: see text] was measured as Rb+ and K+ were exchanged, using ISMs that were approximately five times more sensitive to Rb+ than to K+. When [Formula: see text]was replaced by [Formula: see text], the light-evoked decrease in K+ efflux produced only a small change in ISM voltage, ΔVISM, owing to the background of [Formula: see text]. As [Formula: see text] replaced [Formula: see text], the efflux shifted from K+ to Rb+ and ΔVISM grew in amplitude. After loading the rods with [Formula: see text], [Formula: see text] was replaced by [Formula: see text]. The light-evoked decrease in Rb+ efflux lead transiently to a large ΔVISM, since the change in [Formula: see text], was superimposed upon a background of [Formula: see text]. As [Formula: see text] replaced [Formula: see text], the amplitude of ΔVISM declined. When measured using this technique, the turnover of [Formula: see text] was 95% complete in approximately 15 min. In low Ca2+ solutions, transmembrane fluxes of K+ (Rb+) increased and turnover of [Formula: see text] occurred more rapidly. During background illumination, transmembrane fluxes of K+ (Rb+) decreased and turnover of [Formula: see text] was slowed. These experiments have provided independent corroboration of earlier observations concerning rod K+ fluxes. This ISM-based technique also may be useful in measuring K+ turnover in other cell types.

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Decline of electrogenic Na+/K+ pump activity in rod photoreceptors during maintained illumination.

The Journal of General Physiology ◽

10.1085/jgp.87.4.633 ◽

1986 ◽

Vol 87 (4) ◽

pp. 633-647 ◽

Cited By ~ 12

Author(s):

H Shimazaki ◽

B Oakley

Keyword(s):

Membrane Resistance ◽

Membrane Voltage ◽

Continuous Illumination ◽

Subretinal Space ◽

Rod Photoreceptors ◽

Pharmacological Agents ◽

Pump Activity ◽

Isolated Retina ◽

Voltage Dependent ◽

Toad Bufo

Light-evoked changes in membrane voltage were recorded intracellularly from rod photoreceptors in the isolated retina preparation of the toad, Bufo marinus, during superfusion with a solution containing pharmacological agents that blocked voltage-dependent conductances. Under these conditions, the amplitude of the hyperpolarizing photoresponse became much greater than under control conditions. The results of several experiments support the conclusion that this increase in photoresponse amplitude was due primarily to a voltage that was produced when the electrogenic current from the rods' Na+/K+ pump flowed across an increased membrane resistance (Torre, V. 1982. Journal of Physiology. 333:315). At the onset of a period of continuous illumination, the rod membrane first hyperpolarized and then began to repolarize, and after 180 s of illumination, the membrane voltage had recovered by 60-72% of its initial hyperpolarization. There did not appear to be any significant decrease in rod membrane resistance associated with this repolarization. Both the enhanced hyperpolarization at light onset and the slow repolarization during maintained illumination were blocked by superfusion with 10.0 microM strophanthidin. These data support the hypothesis that the activity of the rods' Na+/K+ pump declines progressively during maintained illumination. It is likely that the decline in pump activity produces significant changes in [K+]o in the subretinal space during maintained illumination.

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Decision letter for "LRRTM4 is a member of the transsynaptic complex between rod photoreceptors and bipolar cells"

10.1002/cne.24944/v2/decision1 ◽

2020 ◽

Keyword(s):

Bipolar Cells ◽

Rod Photoreceptors

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Morphological and elemental analysis of isolated incubated frog retina-choroid

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111604 ◽

1984 ◽

Vol 42 ◽

pp. 298-299

Author(s):

B. J. Panessa-Warren ◽

J. B. Warren ◽

H. W. Kraner

Keyword(s):

Elemental Analysis ◽

Pigment Epithelium ◽

Human Retina ◽

Healthy Individuals ◽

Anterior Portion ◽

Pathological Conditions ◽

Frog Retina ◽

Isolated Retina ◽

Vertebrate Eye ◽

Retina Pigment Epithelium

Our previous studies have demonstrated that abnormally high amounts of calcium (Ca) and zinc (Zn) can be accumulated in human retina-choroid under pathological conditions and that barium (Ba), which was not detected in the eyes of healthy individuals, is deposited in the retina pigment epithelium (RPE), and to a lesser extent in the sensory retina and iris. In an attempt to understand how these cations can be accumulated in the vertebrate eye, a morphological and microanalytical study of the uptake and loss of specific cations (K, Ca,Ba,Zn) was undertaken with incubated Rana catesbiana isolated retina and RPE preparations. Large frogs (650-800 gms) were dark adapted, guillotined and their eyes enucleated in deep ruby light. The eyes were hemisected behind the ora serrata and the anterior portion of the eye removed. The eyecup was bisected along the plane of the optic disc and the two segments of retina peeled away from the RPE and incubated.

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