Relationship between capillaries, mitochondria and maximum power of the heart: a meta-study from shrew to elephant
Date
2022
Authors
Horrell, H.D.
Lindeque, A.
Farrell, A.P.
Seymour, R.S.
White, C.R.
Kruger, K.M.
Snelling, E.P.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Proceedings of the Royal Society of London. Biological Sciences, 2022; 289(1968):20212461-20212461
Statement of Responsibility
Heidi D. Horrell, Anika Lindeque, Anthony P. Farrell, Roger S. Seymour,
Craig R. White, Kayla M. Kruger and Edward P. Snelling
Conference Name
Abstract
This meta-study uses phylogenetic scaling models across more than 30 species, spanning five orders of magnitude in body mass, to show that cardiac capillary numerical density and mitochondrial volume density decrease with body mass raised to the -0.07 ± 0.03 and -0.04 ± 0.01 exponents, respectively. Thus, while an average 10 g mammal has a cardiac capillary density of approximately 4150 mm<sup>-2</sup> and a mitochondrial density of 33%, a 1 t mammal has considerably lower corresponding values of 1850 mm<sup>-2</sup> and 21%. These similar scaling trajectories suggest quantitative matching for the primary oxygen supply and oxygen consuming structures of the heart, supporting economic design at the cellular level of the oxygen cascade in this aerobic organ. These scaling trajectories are nonetheless somewhat shallower than the exponent of -0.11 calculated for the maximum external mechanical power of the cardiac tissue, under conditions of heavy exercise, when oxygen flow between capillaries and mitochondria is probably fully exploited. This mismatch, if substantiated, implies a declining external mechanical efficiency of the heart with increasing body mass, whereby larger individuals put more energy in but get less energy out, a scenario with implications for cardiovascular design, aerobic capacity and limits of body size.
School/Discipline
Dissertation Note
Provenance
Description
Access Status
Rights
© 2022 The Author(s) Published by the Royal Society. All rights reserved.