AJP - Endocrinology and Metabolism, Vol 241, Issue 5 364-E371, Copyright © 1981 by American Physiological Society
Carbohydrate metabolism in isolated, working newborn pig heart
J. C. Werner, V. Whitman, R. R. Fripp, H. G. Schuler and H. E. Morgan
Metabolic activity of the newborn pig heart was observed by means of a
preparation that allowed isolated hearts to perform a physiologic work
load. A 10-min period of retrograde aortic perfusion was followed by 60 min
of recirculating perfusion in which bicarbonate buffer was infused into the
right atrium and ejected from both ventricles at measured pressures and
flow rates. The buffer was supplemented with either glucose (10 mM),
lactate (20 mM), or pyruvate (20 mM), or was unsupplemented. Pressure
development and ventricular outputs were stable through 60 min of perfusion
with glucose, pyruvate, or lactate supplementation. Myocardial high-energy
phosphate and glycogen contents were also stable. In hearts perfused
without substrate supplementation, mechanical performance deteriorated
after 30 min. Rates of substrate uptake and oxygen consumption indicated
that either glucose, lactate, or pyruvate could serve as a primary source
of metabolic energy. Minimal lactate production was observed when either
glucose or pyruvate were present. These findings indicate that, despite
recent emergence from the relatively hypoxic intrauterine environment, the
well-oxygenated newborn pig heart did not depend on anaerobic metabolism of
glucose for energy production at physiologic work loads.
