Advanced Search

Journal Navigation

Journal Home

Subscriptions

Archive

Contact Us

Table of Contents

Click here for more information

Sign In to gain access to subscriptions and/or personal tools.
Journal of Biological Rhythms
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Saved Citations
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Request Reprints
Right arrow Add to My Marked Citations
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Right arrow Citing Articles via Scopus
Google Scholar
Right arrow Articles by Khalsa, S. B. S.
Right arrow Articles by Block, G. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Khalsa, S. B. S.
Right arrow Articles by Block, G. D.
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   Add to Twitter  
What's this?

The Role of Extracellular Calcium in Generating and in Phase-Shifting the Bulla Ocular Circadian Rhythm

Sat Bir S. Khalsa

NSF Center for Biological Timing, Department of Biology, Gilmer Hall, Charlottesville, Virginia 22901

Martin R. Ralph

Department of Psychology, University of Toronto, 100 St. George St. , Toronto, Ontario M5S 1A1, Canada

Gene D. Block

NSF Center for Biological Timing, Department of Biology, Gilmer Hall, Charlottesville, Virginia 22901

Since extracellular calcium is known to be involved in the entrainment of the circadian pacemaker in the retina of Bulla gouldiana, we have assessed the requirement for extracellular calcium in the generation of the circadian rhythm. To enable us to assay the state of the pacemaker during low-calcium treatment, which often obscures rhythmicity, long-duration pulses of low-calcium artificial seawater (no added calcium, 10 mM EGTA, calculated calcium concentration = 4.5 x 10-10 M) were applied, and the phase of the subsequent rhythm was measured. Pulse treatments started at zeitgeber time (ZT) 6, and durations ranged from 4 to 72 hr. Although no phase shifts followed pulses ending before the next projected dawn (ZT 24), phase delays of up to 4 hr followed pulses ending after projected dawn, and delays of up to 8 hr followed pulses spanning two dawns. Some activity records exhibited unequivocal circadian rhythmicity during the long low-calcium treatments, with phases and periods similar to untreated control eye records; this finding suggests that the phase delays observed following long low-calcium pulses are attributable to the pulsatile nature of the treatment. These data suggest that extracellular calcium is not an essential requirement for the pacemaker in generating the circadian rhythm.

Key Words: rhythm • EGTA • neuron • mollusc • oscillator

Journal of Biological Rhythms, Vol. 8, No. 2, 125-139 (1993)
DOI: 10.1177/074873049300800203
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   Add to Twitter Twitter    What's this?


This article has been cited by other articles:


Home page
 J Biol RhythmsHome page
J. Flett and C. S. Colwell
Serotonin Modulation of Calcium Transients in Cells in the Suprachiasmatic Nucleus
J Biol Rhythms, October 1, 1999; 14(5): 354 - 363.
[Abstract] [PDF]

Home page
 J Biol RhythmsHome page
S. Michel, K. Manivannan, J. J. Zaritsky, and G. D. Block
A Delayed Rectifier Current Is Modulated by the Circadian Pacemaker in Bulla
J Biol Rhythms, April 1, 1999; 14(2): 141 - 150.
[Abstract] [PDF]