Cerebral metabolism in sheep: a comparative study of the adult, the lamb, and the fetus.
The cerebral uptakes of glucose, oxygen, lactate, pyruvate, acetoacetate and beta-hydroxybutyrate were compared in the adult, the fetal, and the newborn sheep. Beginning 1-2 days after surgery, we withdrew samples simultaneously from an artery and from the sagittal sinus for up to 2 wk. At all ages glucose was the only substrate taken up in significant quantity relative to oxygen. The glucose-oxygen quotients were 0.98 less than 1.03 less than 1.08 in adults; 0.92 less than 0.99 less than 1.06 in lambs; 0.92 less than 0.98 less than 1.03 in fetuses. These quotients were not significantly different. There was a significant (P less than .05) arteriovenous difference for lactate in the adult (-0.031 mM), but not in the lamb or fetus. A significant (P less than .05) arteriovenous difference pyruvate was found in the adult (-0.013 mM) and in the fetus (-0.020 mM). The findings of a glucose-oxygen quotient of approximately 1 and the lack of significant lactate production in fetal sheep brain are consistent with the hypothesis that anerobic glycolysis is unimportant to the steady-state cerebral metabolism of the fetal sheep.
D000090:Acetoacetates / Q000097:blood / Q000378:metabolism; D000375:Aging; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001784:Blood Gas Analysis; D001786:Blood Glucose; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D006885:Hydroxybutyrates / Q000097:blood / Q000378:metabolism; D007773:Lactates / Q000097:blood / Q000378:metabolism; D010101:Oxygen Consumption; D011773:Pyruvates / Q000097:blood; D012756:Sheep / Q000378:metabolism*
D000090:Acetoacetates; D001786:Blood Glucose; D006885:Hydroxybutyrates; D007773:Lactates; D011773:Pyruvates; D005947:Glucose