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

First published online May 13, 2004
Journal of Experimental Biology 207, 2003-2010 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00957

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 Related articles in JEB 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 McDonald, M. D. Articles by Walsh, P. J. Search for Related Content PubMed PubMed Citation Articles by McDonald, M. D. Articles by Walsh, P. J. Social Bookmarking                         What's this?

Dogmas and controversies in the handling of nitrogenous wastes: 5-HT₂-like receptors are involved in triggering pulsatile urea excretion in the gulf toadfish, Opsanus beta

M. Danielle McDonald^* and Patrick J. Walsh

Division of Marine Biology and Fisheries, NIEHS Marine and Freshwater Biomedical Science Center, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, 33149-1098, USA

^* Author for correspondence (e-mail: dmcdonald{at}rsmas.miami.edu)

Accepted 23 February 2004

When injected arterially, serotonin (5-hydroxytryptamine; 5-HT) has been shown to elicit naturally sized urea pulse events in the gulf toadfish, Opsanus beta. The goal of the present study was to determine which 5-HT receptor(s) was involved in mediating this serotonergic stimulation of the pulsatile excretion mechanism. Toadfish were surgically implanted with caudal arterial catheters and intraperitoneal catheters and injected with either 8-OH-DPAT (1 µmol kg^–1), a selective 5-HT_1A receptor agonist, -methyl-5-HT (1 µmol kg^–1), a 5-HT₂ receptor agonist, or ketanserin, a 5-HT₂ receptor antagonist (0.01, 0.1, 1 and 10 µmol kg^–1) plus -methyl-5-HT. 8-OH-DPAT injection did not mediate an increase in urea excretion, ruling out the involvement of 5-HT_1A receptors in pulsatile excretion. However, within 5 min, -methyl-5-HT injection caused an increase in the excretion of urea in >95% (N=27) of the fish injected, with an average pulse size of 652±102 µmol N kg^–1 (N=26). With -methyl-5-HT injection there was no corresponding increase in ammonia or [³H]PEG 4000 permeability. Urea pulses elicited by -methyl-5-HT were inhibited in a dose-dependent fashion by the 5-HT₂ receptor antagonist ketanserin, which at low doses caused a significant inhibition of pulse size and at higher doses significantly inhibited the occurrence of pulsatile excretion altogether. However, neither 8-OH-DPAT nor -methyl 5-HT injection had an effect on plasma cortisol or plasma urea concentrations. These findings suggest the involvement of a 5-HT₂-like receptor in the regulation of pulsatile urea excretion.

Key words: serotonin, ketanserin, serotonin receptor, -methyl-5-HT, 8-OH-DPAT

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

Related articles in JEB:

SPECIAL COLLECTION: DOGMAS AND CONTROVERSIES IN THE HANDLING OF NITROGENOUS WASTES

Kathryn Phillips
JEB 2004 207: i. [Full Text]  

This article has been cited by other articles:

				T. M. Rodela, K. M. Gilmour, P. J. Walsh, and M. D. McDonald Cortisol-sensitive urea transport across the gill basolateral membrane of the gulf toadfish (Opsanus beta) Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2009; 297(2): R313 - R322. [Abstract] [Full Text] [PDF]

				T. M. Rodela, M. D. McDonald, P. J. Walsh, and K. M. Gilmour The regulatory role of glucocorticoid and mineralocorticoid receptors in pulsatile urea excretion of the gulf toadfish, Opsanus beta J. Exp. Biol., June 15, 2009; 212(12): 1849 - 1858. [Abstract] [Full Text] [PDF]

				M. D. McDonald, B. Vulesevic, S. F. Perry, and P. J. Walsh Urea transporter and glutamine synthetase regulation and localization in gulf toadfish gill J. Exp. Biol., March 1, 2009; 212(5): 704 - 712. [Abstract] [Full Text] [PDF]

				K. Phillips SPECIAL COLLECTION: DOGMAS AND CONTROVERSIES IN THE HANDLING OF NITROGENOUS WASTES J. Exp. Biol., May 15, 2004; 207(12): i - i. [Full Text]