QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online June 29, 2006
Journal of Experimental Biology 209, 2749-2764 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02312

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Woodward, O. M. Articles by Willows, A. O. D. Search for Related Content PubMed PubMed Citation Articles by Woodward, O. M. Articles by Willows, A. O. D. Social Bookmarking                         What's this?

Dopamine modulation of Ca²⁺ dependent Cl^- current regulates ciliary beat frequency controlling locomotion in Tritonia diomedea

Owen M. Woodward^1,2,* and A. O. Dennis Willows^1,2

¹ Department of Biology, University of Washington, Seattle, WA 98195, USA
² Friday Harbor Laboratories, University of Washington, 620 University Road, Friday Harbor, WA 98250, USA

^* Author for correspondence at present address: Department of Physiology, Johns Hopkins School of Medicine, 725 N. Wolfe Street, 214 WBSB, Baltimore, MD 21205, USA (e-mail: owenw{at}jhmi.edu)

Accepted 4 May 2006

The physiological mechanisms controlling ciliary beating remain largely unknown. Evidence exists supporting both hormonal control of ciliary beating and control via direct innervation. In the present study we investigated nervous control of cilia based locomotion in the nudibranch mollusc, Tritonia diomedea. Ciliated pedal epithelial (CPE) cells acting as locomotory effectors may be electrically excitable. To explore this possibility we characterized the cells' electrical properties, and found that CPE cells have large voltage dependent whole cell currents with two components. First, there is a fast activating outward Cl^- current that is both voltage and Ca²⁺ influx dependent (I_Cl(Ca)). I_Cl(Ca) is sensitive to DIDS and 9-AC, and resembles currents of Ca²⁺-activated Cl^- channels (CaCC). Ca²⁺ dependence also suggests the presence of voltage-gated Ca²⁺ channels; however, we were unable to detect these currents. The second current, a voltage dependent proton current (I_H), activates very slowly and is sensitive to both Zn²⁺ and changes in pH.

In addition we identify a new cilio-excitatory substance in Tritonia, viz., dopamine. Dopamine, in the 10 µmol l^-1-1 mmol l^-1 range, significantly increases ciliary beat frequency (CBF). We also found dopamine and Tritonia Pedal Peptide (TPep-NLS) selectively suppress I_Cl(Ca) in CPE cells, demonstrating a link between CBF excitation and I_Cl(Ca). It appears that dopamine and TPep-NLS inhibit I_Cl(Ca) not through changing [Ca²⁺]_in, but directly by an unknown mechanism. Coupling of I_Cl(Ca) and CBF is further supported by our finding that DIDS and zero [Cl^-]_out both increase CBF, mimicking dopamine and TPep-NLS excitation. These results suggest that dopamine and TPep-NLS act to inhibit I_Cl(Ca), initiating and prolonging Ca²⁺ influx, and activating CBF excitation.

Key words: Tritonia diomedea, dopamine, ciliary beat frequency, Ca²⁺ activated Cl^- current

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

This article has been cited by other articles:

				R. D. Longley Development of the 5-HT-like Immunoreactive Pedal Plexus in the Pond Snail Lymnaea stagnalis appressa Biol. Bull., December 1, 2008; 215(3): 280 - 294. [Abstract] [Full Text] [PDF]