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The sea anemone purine, caissarone: adenosine receptor antagonism
Toxicon (1995)
  • Roland A. Cooper, Department of Pharmacology, College of Medicine, University of Arizona
  • JoseCarlos de Freitas, Department of General Physiology, Biosciences Institute, University of São Paulo
  • Frank Porreca, Department of Pharmacology, College of Medicine, University of Arizona
  • Cynthia M. Eisenhour, Barrow Neurological Institute, St Joseph's Hospital and Medical Center
  • Ronald Lukas, Barrow Neurological Institute, St Joseph's Hospital and Medical Center
  • Ryan J. Huxtable, Department of Pharmacology, College of Medicine, University of Arizona
Abstract
Caissarone, a sea anemone iminopurine, produced an increase in the twitch response of the electrically stimulated guinea-pig ileum-myenteric plexus. In the same assay, caissarone reduced the inhibitory response to the endogenous neuromodulator, adenosine, the A1 adenosine receptor agonist, R-phenylisopropyladenosine (R-PIA), and the A2 agonist, 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA) in a dose-dependent manner. Schild plot analysis of antagonism by caissarone yielded slopes of near unity, indicating that caissarone acts as a simple competitive antagonist at the adenosine receptor. The dissociation constants (KB) for caissarone ranged from 0.53 mM to 0.78 mM. In functional nicotinic receptor assays in two human cell lines, caissarone failed either to potentiate or to reduce carbamylcholine-mediated 86Rb+ efflux. Thus, the enhancing activity of caissarone on the gut could not be attributed to activity at the ganglionic nicotinic receptor. Based on structure and pharmacological activity, caissarone appears to be the first marine product described as an adenosine receptor antagonist.
Publication Date
August, 1995
Citation Information
Roland A. Cooper, JoseCarlos de Freitas, Frank Porreca, Cynthia M. Eisenhour, et al.. "The sea anemone purine, caissarone: adenosine receptor antagonism" Toxicon Vol. 33 Iss. 8 (1995) p. 1025 - 1031 ISSN: 0041-0101
Available at: http://works.bepress.com/roland_cooper/3/