Abstract
We measured myocardial blood flow to the left ventricular free wall and blood glucose, lactate, pyruvate, fatty acid, triglyceride, β-OH-butyrate, acetoacetate and oxygen concentrations in aorta (Ao) and coronary sinus (CS) of 6 fetal and 12 8-week-old chronically instrumented lambs at rest. We calculated MVO2 and substrate uptake when Ao and CS concentrations differed significantly. Despite significantly lower fetal Ao oxygen concentrations (3378±737 (SD) vs 5300±589 umol-1-1), MVO2 was not significantly different between the two groups of lambs (454±135 vs 514±194 μmol·min−1.100 g−1). Glucose (30.9±20.3 vs 36.5±52 μmol·min−1.100 g−1) and triglyceride (7.9±5.6 vs 6.6±10.4 μmol·min−1. 100 g−1) uptakes were also similar, while the fetal Ao concentrations were significantly lower (920±171 vs 3850±485 and 123±29 vs 319±114 μmol·1−1, resp.). Besides glucose and triglyceride uptake by the myocardium, the fetuses also showed lactate (108±69 μmol·min−1·100 g−1) and pyruvate uptake (19.8±22.8 μmol·min−·100 g−1), while the 8-week-old lambs showed only β-OH-butyrate uptake (22.0 ± 20.4 μmol·min−1·100 g−1). In both groups of lambs there was no uptake of free fatty acids. Assuming all substrates are metabolized aerobically they could account for 200% of oxygen uptake by the heart in fetal and 8-week-old lambs. We assume that during these studies the surplus of substrate uptake is stored by the myocardium.
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Dalinghaus, M., Toorop, G., Gerding, A. et al. 24 MYOCARDIAL OXYGEN CONSUMPTION (MVO2) AND SUBSTRATE UPTAKE IN FETAL AND 8-WEEK-OLD LAMBS. Pediatr Res 20, 1037 (1986). https://doi.org/10.1203/00006450-198610000-00078
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DOI: https://doi.org/10.1203/00006450-198610000-00078