AJP - Endocrinology and Metabolism, Vol 244, Issue 1 19-E23, Copyright © 1983 by American Physiological Society
Fatty acid and glucose utilization in isolated, working newborn pig hearts
J. C. Werner, V. Whitman, T. C. Vary, R. R. Fripp, J. Musselman and H. G. Schuler
The effects of exogenous fatty acids on glucose uptake were assessed in
isolated, working newborn pig hearts in which great vessel pressures were
controlled (mean 55 mmHg) and oxygenated nutrient buffer was recirculated
through the heart for 30 or 60 min. When palmitate (1.5 mM) or octanoate
(1.0 mM) were added to buffer containing 10 mM glucose and 100 mU
insulin/ml, glucose uptake, as measured by 3H2O production from
D-[2-3H]glucose, was suppressed to less than one-half that observed when
glucose alone was present. Increased tissue levels of glucose 6-phosphate,
fructose 6-phosphate, and citrate following perfusion in the presence of
exogenous fatty acids were consistent with decreased glycolytic activity
due to inhibition of phosphofructokinase. Measurements of carnitine in
perfused and unperfused hearts indicated that total carnitine levels in
neonatal hearts are similar to those of adult pigs. Increased tissue levels
of long-chain acyl carnitine, acetyl carnitine, and citrate in hearts
perfused with palmitate and glucose in combination with extensive fatty
acid uptake and marked suppression of glycolysis indicated that the newborn
pig heart is capable of utilizing fatty acids as a primary energy source.
