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Scaling of cardiac morphology is interrupted by birth in the developing sheep Ovis aries
Author(s) -
Snelling Edward P.,
Seymour Roger S.,
Giussani Dino A.,
Fuller Andrea,
Maloney Shane K.,
Farrell Anthony P.,
Mitchell Duncan,
George Keith P.,
Dzialowski Edward M.,
Jonker Sonnet S.,
Wube Tilaye
Publication year - 2019
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/joa.12990
Subject(s) - medicine , allometry , fetus , body mass index , scaling , anatomy , cardiology , endocrinology , biology , pregnancy , mathematics , geometry , ecology , genetics
Scaling of the heart across development can reveal the degree to which variation in cardiac morphology depends on body mass. In this study, we assessed the scaling of heart mass, left and right ventricular masses, and ventricular mass ratio, as a function of eviscerated body mass across fetal and postnatal development in Horro sheep Ovis aries (~50‐fold body mass range; N = 21). Whole hearts were extracted from carcasses, cleaned, dissected into chambers and weighed. We found a biphasic relationship when heart mass was scaled against body mass, with a conspicuous ‘breakpoint’ around the time of birth, manifest not by a change in the scaling exponent (slope), but rather a jump in the elevation. Fetal heart mass (g) increased with eviscerated body mass ( M b , kg) according to the power equation 4.90 M b 0.88 ± 0.26 (± 95% CI ) , whereas postnatal heart mass increased according to 10.0 M b 0.88 ± 0.10 . While the fetal and postnatal scaling exponents are identical (0.88) and reveal a clear dependence of heart mass on body mass, only the postnatal exponent is significantly less than 1.0, indicating the postnatal heart becomes a smaller component of body mass as the body grows, which is a pattern found frequently with postnatal cardiac development among mammals. The rapid doubling in heart mass around the time of birth is independent of any increase in body mass and is consistent with the normalization of wall stress in response to abrupt changes in volume loading and pressure loading at parturition. We discuss variation in scaling patterns of heart mass across development among mammals, and suggest that the variation results from a complex interplay between hard‐wired genetics and epigenetic influences.