The Journal of General Physiology
Cell MicroControls
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published 28 April 2003. doi:10.1085/jgp.200208778
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 459K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JGP
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Fein, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fein, A.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?
© Rockefeller University Press, 0022-1295/2003/5/441/ $5.00
Journal of General Physiology, Volume 121, Number 5, May 2003 441-449
Inositol 1,4,5-trisphosphate–induced Calcium Release Is Necessary for Generating the Entire Light Response of Limulus Ventral Photoreceptors

Alan Fein

Department of Physiology, University of Connecticut Health Center, Farmington, CT 06030

Address correspondence to: Alan Fein, Department of Physiology, University of Connecticut Health Center, Farmington CT, 06030-3505. Fax: (860) 679-1269; E-mail: afein{at}neuron.uchc.edu

The experiments reported here were designed to answer the question of whether inositol 1,4,5-trisphosphate (IP3)-induced calcium release is necessary for generating the entire light response of Limulus ventral photoreceptors. For this purpose the membrane-permeable IP3 receptor antagonist 2-aminoethoxydiphenyl borate (2APB) (Maruyama, T., T. Kanaji, S. Nakade, T. Kanno, and K. Mikoshiba. 1997. J. Biochem. (Tokyo). 122:498–505) was used. Previously, 2APB was found to inhibit the light activated current of Limulus ventral photoreceptors and reversibly inhibit both light and IP3 induced calcium release as well as the current activated by pressure injection of calcium into the light sensitive lobe of the photoreceptor (Wang, Y., M. Deshpande, and R. Payne. 2002. Cell Calcium. 32:209). In this study 2APB was found to inhibit the response to a flash of light at all light intensities and to inhibit the entire light response to a step of light, that is, both the initial transient and the steady-state components of the response to a step of light were inhibited. The light response in cells injected with the calcium buffer 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was reversibly inhibited by 2APB, indicating that these light responses result from IP3-mediated calcium release giving rise to an increase in Cai. The light response obtained from cells after treatment with 100 µM cyclopiazonic acid (CPA), which acts to empty intracellular calcium stores, was reversibly inhibited by 2APB, indicating that the light response after CPA treatment results from IP3-mediated calcium release and a consequent rise in Cai. Together these findings imply that IP3-induced calcium release is necessary for generating the entire light response of Limulus ventral photoreceptors.

Key Words: phototransduction • microvillar photoreceptors • inositol 1,4,5-trisphosphate receptor • 2-aminoethoxydiphenyl borate • calcium buffers


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?




  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents