Abstract
The influence of growth on myocardial energy metabolism is not clear. Mitochondria are the main source of production of ATP in cardiac muscle. Accordingly, mitochondria from the hearts of 9 fetal and 7 newborn lambs, and 9 adult sheep were isolated in KCl-albumin-EDTA media, studied polarographically, and compared biochemically. No age-related differences were found in P/O ratios, a measure of efficiency of ATP production, with either succinate or glutamate as substrate; or in ATPase activities, in the presence or absence of DNP. However, mitochondria from fetal and newborn animals had significantly increased maximum O2 consumption/mg protein in the presence of ADP (state III respiration) (0.19 ± 0.01 S.D. and 0.17 ± 0.01 μatoms/min.) compared to the adult (0.10 ± 0.01, p < 0.001). Thus, increased respiratory control ratios, a measure of the dependence of respiratory rate on ADP, were increased in the fetus (12.9 ± 0.6) and newborn (15.6 ± 2.6) compared to the adult (9.5 ± 0.5 p < 0.001). O2 consumption in mitochonidria uncoupled by DNP, was highest in the fetus and newborn (0.30 ± 0.02 and 0.29 ± 0.02 μatoms/mg protein) compared to the adult (0.16 ± 0.01, p < 0.01). These augmented respiratory rates in mitochondria from the youngest hearts may reflect increased electron transport, a view consistent with the finding of 56% of 65% greater cytochrome oxidase activities in fetal and newborn heart mitochondria, respectively, when compared to the adult. Thus, age-dependent differences exist in cardiac energy metabolism that are of potential importance to our understanding of myocardial function in the perinatal period.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wells, R., Sobel, B. & Friedman, W. Energy production in the developing heart. Pediatr Res 5, 425 (1971). https://doi.org/10.1203/00006450-197108000-00227
Issue Date:
DOI: https://doi.org/10.1203/00006450-197108000-00227