| Autor: |
Drachev, Lel A., Kalamkarov, Grigory R., Kaulen, Andrey D., Ostrovsky, Michail A., Skulachev, Vladimir P. |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; 7/15/81, Vol. 117 Issue 3, p471-481, 11p |
| Abstrakt: |
The functioning of visual rhodopsin as a photoelectric generator has been demonstrated with a direct method. Photoreceptor discs were incorporated into a phospholipid-impregnated collodion film. Illuminatioń of the resulting system with continuous light was found to induce formation of an electric potential (the disc-free side positive) that was measured with two electrodes separated by the film, A photopotential exceeding 40 mV was shown. It dissipated before the light source was switched off. A 15 ns 530-nm laser flash induced the formation of a photopotential of up to 35 mV whose appearance was preceded with a small oppositely directed electrogenic phase. This 'negative' photoresponse took less than 200 ns. The 'positive' photoresponse was composed of at least two phases (t½ about 500 μs and several milliseconds). The latter was shown to correlated with formation of metarhodopsin II. A 347-nm laser flash added after a 530-nm flash resulted in a photoelectric effect similar to that initiated by 530-nm flash but of opposite direction. The 347-nm response was completely abolished by hydroxylamine preventing the accumulation of metarhodopsin II. The response at 530 nm proved to be hydroxylamine-resistant. Both the amplitude and the decay time of the flash-induced potential were maximal in the response to the first flash, each subsequent flash being less effective than the preceding one. Flashes were found to cause acceleration of the photopotential decay. The latter effect proved to be due to a increase of membrane conductance that developed faster than in 50 ms. Addition of 11-cis retinal after illumination improved the amplitude of the photoresponse but not the conductance. The light-induced increase in conductance was insensitive to hydroxylamine. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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