Effect of intracellularly applied sodium ions on the dark voltage of isolated retinal rods

Schmidt, K.; Nöll, Gottfried N.; Baumann, Christian

doi:10.1017/s0952523800004533

Cited by 5 publications

(1 citation statement)

References 19 publications

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“…To reduce or prevent these changes, all substances that are essential for the transduction process should be present in the pipette medium. This is difficult to achieve, but substitution experiments allowed us to estimate intracellular concentrations of nucleotides (Schmidt et al, 1989c) and sodium ions (Schmidt et al, 1990). Here we report that the intracellular application of the nitric-oxide-releasing substance sodium nitroprusside has a marked influence on the dark voltage and the light responses of rods.…”

Section: Introductionmentioning

confidence: 99%

Sodium nitroprusside alters dark voltage and light responses in isolated retinal rods during whole-cell recording

Schmidt

Nöll²,

Yamamoto³

1992

Vis Neurosci

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Dark voltage and light responses of isolated retinal rods of Rana esculenta were investigated by employing the whole-cell patch-clamp technique. When the recording pipette was filled with a medium devoid of nucleotides, a spontaneous hyperpolarization of the dark voltage partly due to a diffusional loss of cGMP and its precursor GTP and a retardation in the recovery of the light responses was observed. The larger part of the retardation of the light responses was prevented by 1 mM ATP. Addition of GTP attenuated the hyperpolarization, but did not abolish it completely. When the nitric-oxide-releasing substance sodium nitroprusside plus GTP was applied, the tendency of hyperpolarization disappeared and a stable dark voltage or even a slight depolarization was measured during the whole-cell recording period. Similar results were also obtained when GTP was given in combination with either EGTA or IBMX which are both known to interfere with the cGMP regulating enzymes in retinal rods. In addition to its effects on the dark voltage, an acceleration of the recovery phase of the light responses by sodium nitroprusside was also observed. Our observations strongly suggest that sodium nitroprusside activates guanylate cyclase in photoreceptors, as it does in other tissues, but we cannot exclude with certainty an effect on the phosphodiesterase.

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Section: Introductionmentioning

confidence: 99%

Sodium nitroprusside alters dark voltage and light responses in isolated retinal rods during whole-cell recording

Schmidt

Nöll²,

Yamamoto³

1992

Vis Neurosci

Self Cite

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Configuration of light responses in isolated retinal rods

Schmidt

Nöll

Jacobi

et al. 1994

Graefe's Arch Clin Exp Ophthalmol

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The whole-cell patch-clamp technique was employed to investigate the light responses of single retinal rods of the frog (Rana esculenta and R. temporaria). In the majority of experiments, completely isolated cells were studied. Coupling with neighboring cells gave rise to a more complex response configuration. Responses were recorded under voltage-clamp and under current-clamp conditions. Stimulus response curves were measured in experiments with local stimuli illuminating only parts of the outer segment. Metabolic factors such as cGMP, GTP and ATP were also tested and were found to have specific and different influences on the response configurations. When the recording pipette was filled with an intracellular medium devoid of nucleotides, a retardation in the recovery of the light responses was observed during the course of an experiment. Addition of 1 mM ATP to the pipette medium prevented the larger part of the retardation, while 1 mM GTP accelerated the response recovery at the beginning of an experiment but did not prevent a subsequent retardation. Micromolar concentrations of cGMP were sufficient to elicit both a depolarization of the photoreceptor membrane and an increase in the response duration. These results show that, in single photoreceptors, the configuration of light responses not only depends on the stimulus parameters but also on those properties of the cells that are directly controlled by their nucleotide metabolism.

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Size and chirality of intracellularly applied anions affect the function of isolated photoreceptors

et al. 1992

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The effect of intracellularly applied anions on the function of retinal rods of the frog Rana esculenta was investigated by means of the whole-cell patch-clamp technique. When the recording pipette contained a medium based on potassium chloride, a slow spontaneous hyperpolarization was observed presumably due to a diffusional loss of the photoreceptor's internal transmitter cyclic guanosine monophosphate (cGMP) and its precursor guanosine triphosphate (GTP). When chloride was replaced by organic anions such as acetate, aspartate, or gluconate the speed of hyperpolarization diminished and the dark voltage of the rods was stabilized. The extent of stabilization correlates with the molecular weight of the anions. A significant difference in the stabilizing effect was found for L-aspartate and D-aspartate, suggesting an additional influence of the chirality. Effects of some of the anions on the configuration of the light responses were also observed.

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Effect of intracellularly applied sodium ions on the dark voltage of isolated retinal rods

Cited by 5 publications

References 19 publications

Sodium nitroprusside alters dark voltage and light responses in isolated retinal rods during whole-cell recording

Sodium nitroprusside alters dark voltage and light responses in isolated retinal rods during whole-cell recording

Configuration of light responses in isolated retinal rods

Size and chirality of intracellularly applied anions affect the function of isolated photoreceptors

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