The Role of Inositol Phosphate Cascade in Visual Excitation of Invertebrate Microvillar Photoreceptors

Authors

Tamara M. Frank, University of ConnecticutFollow
A. Fein, University of Connecticut

Document Type

Article

Publication Date

4-1991

Publication Title

Journal of General Physiology

ISSN

0022-1295

Volume

97

Issue/No.

4

First Page

697

Last Page

723

Abstract

The identity of the transmitter(s) involved in visual transduction in invertebrate microvillar photoreceptors remains unresolved. In this study, the role of inositol 1,4,5-trisphosphate (IP₃) was examined in Limulus ventral photoreceptors by studying the effects on the light response of heparin and neomycin, agents that inhibit the production or action of IP₃. Both heparin and neomycin reduce responses to brief flashes of light and the transient component of responses to steps of light, and also inhibit IP₃-induced calcium release, indicating that IP₃ plays a direct role in invertebrate visual excitation. The effects of BAPTA, a calcium buffer, were also examined and shown to be consistent with a role for IP₃-mediated calcium release in visual excitation. However, all three agents fail to block the plateau component of the response to a step of light, indicating that a single pathway involving IP₃ and calcium cannot solely be responsible for visual excitation in invertebrates. We suggest that the inositol phosphate cascade and a second parallel process that is not dependent on IP₃ are involved in the production of the light response.

Comments

©1991 Rockefeller University Press

Additional Comments

National Institutes of Health grant #: EY-03793

NSUWorks Citation

Tamara M. Frank and A. Fein. 1991. The Role of Inositol Phosphate Cascade in Visual Excitation of Invertebrate Microvillar Photoreceptors .Journal of General Physiology , (4) : 697 -723. https://nsuworks.nova.edu/occ_facarticles/392.

DOI

10.1085/jgp.97.4.697