The electrocardiogram of vertebrates: Evolutionary changes from ectothermy to endothermy

Author(s):Show less -

Boukens, Bastiaan J. D. ^[1] ; Kristensen, Ditte L. ^[2] ; Filogonio, Renato ^{[3, 4]} ; Carreira, Laura B. T. ^[4] ; Sartori, Marina R. ^{[4, 5]} ; Abe, Augusto S. ^[4] ; Currie, Shannon ^[6] ; Joyce, William ^[2] ; Conner, Justin ^[7] ; Opthof, Tobias ^[8] ; Crossley, II, Dane A. ; Wang, Tobias ^[2] ; Jensen, Bjarke ^[1]

Affiliation

^[1] Univ Amsterdam, Amsterdam UMC, Dept Med Biol, Amsterdam Cardiovasc Sci, Meibergdreef 15, Room L2-106, NL-1105 AZ Amsterdam - Netherlands

^[2] Aarhus Univ, Dept Biosci, Zoophysiol, Aarhus - Denmark

^[3] Fed Univ Sao Carlos UFSCar, Dept Physiol Sci, Sao Carlos, SP - Brazil

^[4] State Univ Sao Paulo UNESP, Dept Zool, Rio Claro, SP - Brazil

^[5] Univ Campinas UNICAMP, Dept Clin Pathol, Campinas, SP - Brazil

^[6] Leibniz Inst Zoo & Wildlife Res, Berlin - Germany

^[7] II, Univ North Texas, Dept Biol Sci, Denton, TX - USA

^[8] Acad Med Ctr, Dept Expt Cardiol, Amsterdam - Netherlands

• Document type: Review article
• Source: PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY; v. 144, p. 16-29, JUL 2019.
• Web of Science Citations: 4

Abstract

The electrocardiogram (ECG) reveals that heart chamber activation and repolarization are much faster in mammals and birds compared to ectothermic vertebrates of similar size. Temperature, however, affects electrophysiology of the heart and most data from ectotherms are determined at body temperatures lower than those of mammals and birds. The present manuscript is a review of the effects of temperature on intervals in the ECG of ectothermic and endothermic vertebrates rather than a hypothesis-testing original research article. However, the conclusions are supported by the inclusion of original data (Iguana iguana, N = 4; Python regius, N = 5; Alligator mississippiensis, N = 4). Most comparisons were of animals of approximately 1 kg. Compared to mammals and birds, the reptiles at 35-37 degrees C had 4 fold lower heart rates, 2 fold slower atrial and ventricular conduction (longer P- and QRS-wave durations), and 4 fold longer PR intervals (atrioventricular delay) and QT intervals (total ventricular repolarization). We conclude that the faster chamber activation in endotherms cannot be explained by temperature alone. Based on histology, we show that endotherms have a more compact myocardial architecture. In mammals, disorganization of the compact wall by fibrosis associates with conduction slowing and we suggest the compact tissue architecture allows for faster chamber activation. The short cardiac cycle that characterizes mammals and birds, however, is predominantly accommodated by shortening of the atrioventricular delay and the QT interval, which is so long in a 1 kg iguana that it compares to that of an elephant. (C) 2018 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 12/16537-0 - Cardiovascular autonomic control and metabolism in lizard embryos (Reptilia; Lepidosauria)
• Grantee: Marina Rincon Sartori
• Support Opportunities: Scholarships in Brazil - Doctorate