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Afterpotentials in dronefly retinula cells

Date

1977-01

Authors

Tsukahara, Y.
Horridge, George Adrian
Stavenga, D. G.

Journal Title

Journal ISSN

Volume Title

Publisher

Springer Verlag (Germany)

Abstract

The wavelength dependence of the afterpotentials following a bright illumination was studied in single photoreceptor cells of the droneflyEristalis. Cells with only a spectral sensitivity peak in the blue were selected. As previously demonstrated, these cells contain a rhodopsin absorbing maximally at about 450–460 nm, which upon photoconversion transforms into a metarhodopsin absorbing maximally at about 550 nm (Tsukahara and Horridge, 1977). With the visual pigment initially all in the rhodopsin form, a high rate of visual pigment conversion results in an afterhyperpolarization (AHP) when the fraction of metarhodopsin remains negligible after illumination as occurs at longer wavelengths if the intensity is high. Intensive illumination at short wavelengths is followed by a prolonged depolarizing afterpotential (PDA). The magnitude of the PDA peaks at low intensities at about 450–460 nm, corresponding to the peak of the cell's spectral sensitivity (i.e. the rhodopsin peak). With increasing intensity of illumination, however, the peak shifts progressively towards 430 nm, which corresponds to the photoequilibrium with maximum metarhodopsin that can be established by monochromatic light. From this result, it is inferred that the PDA is related to the induced fall in the rhodopsin fraction. The PDA can be abolished, or knocked down, by a long-wavelength flash which reconverts remaining metarhodopsin into rhodopsin. Therefore the decline of the PDA is restrained by the existing amount of metarhodopsin. Possible theories of afterpotentials are discussed.

Description

Keywords

Short Wavelength, Long Wavelength, Spectral Sensitivity, Photoreceptor Cell, Visual Pigment

Citation

Source

Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1007/BF00657322

Restricted until

2037-12-31