AJP - Endocrinology and Metabolism, Vol 262, Issue 1 E46-E51, Copyright © 1992 by American Physiological Society
Hepatic metabolism of glucose, galactose, and lactate after milk feeding in newborn lambs
S. B. Spedale, F. C. Battaglia and J. W. Sparks
Department of Pediatrics, University of Colorado School of Medicine, Denver 80262.
The purpose of this study was to test the ability of the liver to
efficiently clear substrates absorbed from the gastrointestinal tract after
a feeding before entry into the systemic circulation. We placed a hepatic
vein (HV) catheter in utero at 135-140 days gestation. The lamb was then
allowed to deliver spontaneously, and additional catheters were placed in
the portal vein (PV) and femoral artery (FA) at 1-3 days postnatal age.
After at least 2 days recovery, lambs were fasted overnight at 4-10 days of
age and then allowed to nurse ad libitum. There was significant hepatic
glucose release during fasting and after 80 min postprandially. No net
hepatic uptake of glucose was observed before or after feeding. PV
galactose was significantly greater than FA and HV from 40 to 160 min after
feeding (P less than 0.005). Hepatic glucose extraction was negligible in
the fasted state (1 +/- 3%) and increased after feeding to 75 +/- 2% when
PV galactose was less than 1.0 mM. There was a significant hepatic
arteriovenous concentration difference of lactate (0.23 +/- 0.03 mM) and of
oxygen (0.27 +/- 0.01 mM), which did not change significantly after
feeding. The metabolic quotient for galactose increased significantly after
feeding, such that galactose was the largest carbon contributor for
postprandial hepatic carbon accretion. After a milk feeding, the newborn
liver efficiently extracts galactose, lactate, and oxygen, but not glucose.
