Gast ::
| Hauptseite > Publikationsdatenbank > Conductance change of the arthropod visual cell membrane in response to light, indirectly depending on membrane potential |
| Hauptseite > Publikationsdatenbank > Conductance change of the arthropod visual cell membrane in response to light, indirectly depending on membrane potential |
| Book/Report | FZJ-2018-00718 |
; ; ; ;
1976
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/16673
Report No.: Juel-1331
Abstract: In retinular cells of Astacus and Limulus the following electrical characteristics of the visual cell membrane were measured by a single intracellular microelectrode: (1) the pre-stimulus membrane potential, pMP; (2) the light-induced receptor potential, ReP; (3) the input resistance of the measuring circuit in the dark; Rd, which is the sum of the resistances of cell membrane, visual cell and recording electrode; and (4) its light-induced change $\Delta$R, which can be attributed mainly to a change in membrane resistance. Results: 1) During the light response both membrane resistance and membrane potential change with a similar but not identical time course. After reaching a maximum value the amplitude of the ReP decreases faster than $\Delta$R. This difference is greater at high light intensity of the stimulus than at lowintensity. 2) A method is described to record simultaneously intracellularly from one retinular cell and extracellularly from the whole isolated retina of Astacus. The ratio of the extracellularly recorded value over the intracellularly recorded one (e/i) was determined for different parameters of RePs recorded under various experimental conditions. The ratio e/i for the absolute amplitude values (voltages) of the ReP is ca. 0.05. The ratio e/i for the time parameters of the ReP is close to 1. The intensity dependence of extra- and intracellularly recorded responses is fairly similar. The effect of high external potassium concentration on extra- and intracellularlyrecorded RePs is also similar, except for the fact that the maximal amplitude h$_{max}$ of the intracellularly recorded response goes down to zero whereas the extracellularly recorded response remains at a small constant value. The reversibility to injuring experimental manipulations (potassium depolarization, ouabain poisoning) is much better for extracellular measurements. 3) Poisoning of Limulus retinular cells by $\underline{ouabain}$ leads to a transient increase of pMP and ReP, followed by a decrease, which is faster for the ReP (t$_{1/2}$ 34 $\pm$ 4.3 min) than for pMP (t$_{1/2}$ 64 $\pm$ 17 min). Inexcitability occurs when the pMP is still ca. 40% of its reference value. The dark resistance R$_{d}$ is slightly increased under the influence of ouabain. The changes are not reversible, in contrast to extracellular recordings in the Astacus retina. 4) Due to high $\underline{external}$ $\underline{potassium}$ (without external sodium) in Limulus retinular cells the pMP reverses polarity (to +20 mV). The ReP decreases, but even after depolarization of the pMP beyond zero there is still a positive going ReP measurable for ca. 10 mine The dark resistance decreases to ca. 50%. All changes are reversible.
|
The record appears in these collections: |
PDF
PDF (PDFA)