HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 289/1/R77    most recent 00647.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science 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 ISI Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Milton, S. L. Articles by Lutz, P. L. Search for Related Content PubMed PubMed Citation Articles by Milton, S. L. Articles by Lutz, P. L.

COMPARATIVE AND EVOLUTIONARY PHYSIOLOGY

Adenosine and ATP-sensitive potassium channels modulate dopamine release in the anoxic turtle (Trachemys scripta) striatum

Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida

Submitted 21 September 2004 ; accepted in final form 14 February 2005

Excessive dopamine (DA) is known to cause hypoxic/ischemic damage to mammalian brain. The freshwater turtle Trachemys scripta, however, maintains basal striatal DA levels in anoxia. We investigated DA balance during early anoxia when energy status in the turtle brain is compromised. The roles of ATP-sensitive potassium (K_ATP) channels and adenosine (AD) receptors were investigated as these factors affect DA balance in mammalian neurons. Striatal extracellular DA was determined by microdialysis with HPLC in the presence or absence of the specific DA transport blocker GBR-12909, the K_ATP blocker 2,3-butanedione monoxime, or the nonspecific AD receptor blocker theophylline. We found that in contrast to long-term anoxia, blocking DA reuptake did not significantly increase extracellular levels in 1-h anoxic turtles. Low DA levels in early anoxia were maintained instead by activation of K_ATP channels and AD receptors. Blocking K_ATP resulted in a 227% increase in extracellular DA in 1-h anoxic turtles but had no effect after 4 h of anoxia. Similarly, blocking AD receptors increased DA during the first hour of anoxia but did not change DA levels at 4-h anoxia. Support for the role of K_ATP channels in DA balance comes from normoxic animals treated with K_ATP opener; infusing diazoxide but not adenosine into the normoxic turtle striatum resulted in an immediate DA decrease to 14% of basal values within 1.5 h. Alternative strategies to maintain low extracellular levels may prevent catastrophic DA increases when intracellular energy is compromised while permitting the turtle to maintain a functional neuronal network during long-term anoxia.

anoxia tolerance; microdialysis; theophylline; GBR-12909; 2,3-butanedione monoxime

This article has been cited by other articles:

				Y. Li, W. Zhou, X. Li, S. Zeng, and Q. Luo Dynamics of Learning in Cultured Neuronal Networks with Antagonists of Glutamate Receptors Biophys. J., December 15, 2007; 93(12): 4151 - 4158. [Abstract] [Full Text] [PDF]