Title

Excitation of Limulus Photoreceptors by Hydrolysis-Resistant Analogs of cGMP and cAMP

Document Type

Article

Publication Date

6-28-1991

Publication Title

Brain Research

Keywords

Limulus polyphemus, Photoreceptor, Cyclic guanosine 5′-phosphate, Cyclic adenosine 5′-phosphate

ISSN

0006-8993

Volume

552

Issue/No.

2

First Page

291

Last Page

294

Abstract

cGMP was proposed to be the agent which directly opens the light-sensitive channel in Limulus ventral photoreceptors. However, the light-sensitive rhabdomeral-lobe (R-lobe) is not uniformly responsive to cGMP injection; that is, there are ‘hot spots’ of sensitivity. A potent phosphodiesterase which rapidly hydrolyses cGMP was suggested to explain the existence of these ‘hot spots’. To test this idea we injected ventral photoreceptors with hydrolysis-resistant cyclic nucleotide analogues. Whereas there can be a lack of a response to cGMP injection into the R-lobe, we find a reproducible depolarization upon R-lobe injection of hydrolysis-resistant cGMP analogues. Furthermore, the depolarization resulting from the injection of cGMP analogues does not require a rise in intracellular Ca2+, as it is not blocked by the Ca2+ buffer, BAPTA. Surprisingly, R-lobe injection of a hydrolysis-resistant cAMP analogue also depolarized ventral photoreceptors. Further work will be needed to resolve the role of cGMP in Limulus visual transduction.

Comments

©1991 Published by Elsevier B.V.

ORCID ID

0000-0002-9329-2414

DOI

10.1016/0006-8993(91)90094-C

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