title: Purinoceptors exert negative inotropic effects on the heart in all major groups of reptiles.
abstract: The few and fragmentary studies on purinergic regulation of the reptile heart have reached equivocal conclusions. Indeed, unlike fish, amphibians, and mammals, it has been suggested that the turtle heart lacks purinoceptors. Here, we study the effect of adenosine and ATP on isolated heart strips from three species of reptiles: the red-eared slider (Trachemys scripta), the ball python (Python regius) and the spectacled caiman (Caiman crocodilus). Both adenosine and ATP markedly decreased contractility in atria from all three species. This was attenuated by theophylline, suggesting that the response is mediated by P1 receptors. Ventricles were less sensitive, although high concentrations of the adenyl compounds evoked decreases in contractility. Our study suggests that cardiac purinoceptors are ubiquitous across reptiles, and may play an important and underappreciated role in reptile cardiovascular physiology.
authors: Zoophysiology, Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark; Faculty of Life Sciences, The University of Manchester, M13 9PT, UK. Electronic address: william.joyce@student.manchester.ac.uk.
authors: William
authors: W
authors: Joyce
authors: Zoophysiology, Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark.
authors: Hans
authors: H
authors: Gesser
authors: Zoophysiology, Department of Biosciences, Aarhus University, DK-8000 Aarhus C, Denmark.
authors: Tobias
authors: T
authors: Wang
mesh_terms: D000064:Acclimatization / Q000187:drug effects; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000489:Alligators and Crocodiles / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D017821:Boidae / Q000378:metabolism; D003080:Cold Temperature; D006352:Heart Ventricles / Q000187:drug effects; D006358:Hot Temperature; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000378:metabolism*; D014426:Turtles / Q000378:metabolism
chemical_list: D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D000241:Adenosine
keywords: Adenosine; Cardiovascular; Reptile; Turtle