AJP - Endocrinology and Metabolism, Vol 259, Issue 6 E865-E871, Copyright © 1990 by American Physiological Society
Adipocyte lactate production remains elevated during refeeding after fasting
F. D. Newby, L. K. Wilson, S. V. Thacker and M. DiGirolamo
Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30303.
The metabolic state occurring with refeeding after fasting is characterized
by the rapid restoration of hepatic glycogen. Recent evidence suggests that
a main substrate for glycogenesis is lactate. Because adipose tissue is an
active site of lactate production that increases with fasting, we examined
the magnitude and duration of lactate production by isolated adipocytes
from three adipose depots of rats fasted for 48 h and then refed for up to
96 h. The data show that 48 h of fasting results in a markedly elevated
rate of adipocyte lactate production, which increased from 3-9% of total
glucose metabolized in the fed state to 49-60% in the fasted state. During
the refeeding period, lactate production remained elevated for 12-24 h and
then declined. Mesenteric adipocytes had a higher rate and more prolonged
elevation in lactate production than cells from the other two depots. We
conclude that, with refeeding after a fast, adipocyte glucose conversion to
lactate remains elevated during the time of hepatic glycogen restoration.
This suggests that adipose tissue may actively produce lactate for
glycogenesis during refeeding.
