Kw. Perry et al., GLUCOSE AND L-LACTATE METABOLISM IN PREGNANT AND IN LACTATING EWES FED BARLEY-BASED OR GROUND MAIZE-BASED DIETS, Experimental physiology, 79(1), 1994, pp. 35-46
The contribution of glucose absorbed from the small intestine to whole
-body glucose metabolism was examined in ewes during late pregnancy an
d early lactation, using diets based on ground barley or ground maize.
Glucose and L-lactate turnover in the whole body and the mesenteric-d
rained viscera were investigated in these ewes using isotope dilution
techniques. The net absorption of glucose by the mesenteric-drained vi
scera and whole-body glucose turnover were unaffected by diet or repro
ductive status. Arterial and mesenteric venous blood glucose concentra
tions, arterial and mesenteric venous L-lactate concentrations and who
le-body lactate turnover were all significantly higher in lactation th
an in pregnancy. The whole-body rates of lactate conversion to glucose
and to other products were significantly higher in lactation than in
pregnancy. Using a two-pool model of whole-body glucose and lactate me
tabolism, a relatively high percentage of glucose was converted to lac
tate (64-84%), accounting for 60-80% of whole-body lactate turnover. A
model of glucose and lactate metabolism by the mesenteric-drained vis
cera was constructed. Both the calculated endogenous glucose productio
n and the visceral conversion of glucose to lactate were greater in la
ctation than in pregnancy when barley was fed. Calculated total glucos
e absorption was relatively constant, contributing between 26 and 59%
of whole-body glucose turnover. Diet had little effect on glucose and
lactate metabolism in either the mesenteric-drained viscera or the who
le-body of breeding ewes.