title: Reduction of blood oxygen levels enhances postprandial cardiac hypertrophy in Burmese python (Python bivittatus).
abstract: Physiological cardiac hypertrophy is characterized by reversible enlargement of cardiomyocytes and changes in chamber architecture, which increase stroke volume and via augmented convective oxygen transport. Cardiac hypertrophy is known to occur in response to repeated elevations of O2 demand and/or reduced O2 supply in several species of vertebrate ectotherms, including postprandial Burmese pythons (Python bivittatus). Recent data suggest postprandial cardiac hypertrophy in P. bivittatus is a facultative rather than obligatory response to digestion, though the triggers of this response are unknown. Here, we hypothesized that an O2 supply-demand mismatch stimulates postprandial cardiac enlargement in Burmese pythons. To test this hypothesis, we rendered animals anemic prior to feeding, essentially halving blood oxygen content during the postprandial period. Fed anemic animals had heart rates 126% higher than those of fasted controls, which, coupled with a 71% increase in mean arterial pressure, suggests fed anemic animals were experiencing significantly elevated cardiac work. We found significant cardiac hypertrophy in fed anemic animals, which exhibited ventricles 39% larger than those of fasted controls and 28% larger than in fed controls. These findings support our hypothesis that those animals with a greater magnitude of O2 supply-demand mismatch exhibit the largest hearts. The 'low O2 signal' stimulating postprandial cardiac hypertrophy is likely mediated by elevated ventricular wall stress associated with postprandial hemodynamics.
authors: Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA Zoophysiology, Institute for Biological Sciences, Aarhus University, DK-8000 Aarhus, Denmark.
authors: Christopher E
authors: CE
authors: Slay
authors: Zoophysiology, Institute for Biological Sciences, Aarhus University, DK-8000 Aarhus, Denmark Inderdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus, Denmark.
authors: Sanne
authors: S
authors: Enok
authors: Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA 92697, USA.
authors: James W
authors: JW
authors: Hicks
authors: Zoophysiology, Institute for Biological Sciences, Aarhus University, DK-8000 Aarhus, Denmark tobias.wang@biology.au.dk.
authors: Tobias
authors: T
authors: Wang
mesh_terms: D000740:Anemia / Q000097:blood / Q000150:complications; D000818:Animals; D017821:Boidae / Q000097:blood* / Q000502:physiology*; D006332:Cardiomegaly / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D004063:Digestion; D005215:Fasting; D006321:Heart / Q000502:physiology / Q000503:physiopathology; D006339:Heart Rate; D010100:Oxygen / Q000097:blood*; D019518:Postprandial Period
chemical_list: D010100:Oxygen
keywords: Anemia; Cardiac plasticity; Cardiovascular regulation; Digestion; Heart; Postprandial; Python molurus bivittatus; Reptile; SDA