TY - JOUR
AU - Friedman, William F
AB - 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.
TI - Energy production in the developing heart
JF - Pediatric Research
DO - 10.1203/00006450-197108000-00227
DA - 1971-08-01
UR - https://www.deepdyve.com/lp/springer-journals/energy-production-in-the-developing-heart-Mok1iImiG0
SP - 425
EP - 425
VL - 5
IS - 8
DP - DeepDyve
ER -