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Catecholamines are key modulators of ventricular repolarization patterns in the ball python (Python regius).

Bastiaan J D Boukens1, William Joyce2, Ditte Lind Kristensen2

  • 1University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands.

The Journal of General Physiology
|December 15, 2021
PubMed
Summary
This summary is machine-generated.

Changes in T-wave polarity in ball pythons are driven by the sympathetic nervous system, not body temperature. This suggests conserved mechanisms for ventricular repolarization in both pythons and mammals.

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Area of Science:

  • Comparative physiology
  • Cardiovascular electrophysiology
  • Herpetology

Background:

  • Ectotherms exhibit daily body temperature fluctuations impacting physiological processes.
  • Ventricular repolarization, reflected by the T-wave on ECG, is known to change with temperature in ectotherms.
  • Mammalian ventricular repolarization is influenced by heart rate and sympathetic activity.

Purpose of the Study:

  • To investigate the roles of body temperature, heart rate, and catecholamines in modulating ventricular repolarization in ball pythons (Python regius).
  • To understand the underlying mechanisms of T-wave polarity changes in ectothermic reptiles.

Main Methods:

  • Recorded body-surface electrocardiograms and performed epicardial mapping in pythons during controlled temperature increases.
  • Utilized RNA sequencing to identify regional differences in adrenergic signaling pathways.
  • Conducted experiments on isolated, perfused python hearts and in awake pythons with pharmacological interventions (agonists and antagonists).

Main Results:

  • T-wave polarity changes were observed in pythons with increasing body temperature, but the repolarization vector varied individually.
  • RNA sequencing indicated regional differences in adrenergic signaling.
  • In isolated hearts, noradrenaline induced T-wave changes, while heating did not.
  • Pharmacological administration of beta-adrenergic agonists (adrenaline, isoproterenol) caused T-wave inversion in awake pythons.
  • Beta-adrenergic receptor blockade with propranolol prevented T-wave changes during heating.

Conclusions:

  • Ventricular repolarization changes in ball pythons are primarily mediated by increased sympathetic nervous system tone, not direct effects of temperature.
  • Catecholaminergic stimulation plays a crucial role in modulating ventricular repolarization in pythons.
  • These findings highlight conserved, catecholamine-dependent mechanisms of ventricular repolarization across ectothermic and endothermic vertebrates.