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 Title

Journal of General Physiology

ISSN

0022-1295

Publication Date

4-1991

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.

DOI

10.1085/jgp.97.4.697

Volume

97

Issue

4

First Page

697

Last Page

723

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.