AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 6 1262-R1269, Copyright © 1993 by American Physiological Society
Cerebral metabolism and electrocortical activity in the chronically hyperglycemic fetal lamb
T. S. Rosenkrantz, I. Knox, E. L. Zalneraitis, J. R. Raye, P. J. Porte, R. Cramer, R. Smoloski and A. F. Phillipps
Department of Pediatrics, University of Connecticut Health Center, Farmington 06030.
Previous studies in the fetal lamb have demonstrated that hyperglycemia
stimulates the fetal metabolic rate. The present study examined the effects
of chronic fetal hyperglycemia on fetal cerebral metabolic rate and
electrocortical activity. Nine chronically instrumented fetal lambs had
measurements of cerebral blood flow and cerebral uptake/excretion of
oxygen, glucose, lactate, and beta-hydroxybutyrate taken before and during
a 48-h fetal glucose infusion. Electrocortical activity was also recorded.
The fetal arterial glucose concentration was 19.8 +/- 2.0 mg/dl before
glucose infusion and 48 +/- 4.5 to 54.6 +/- 6.6 mg/dl during the infusion
period. Cerebral blood flow and cerebral glucose and oxygen uptake
increased by 219, 209, and 171%, respectively, by the end of the infusion
period. There was a linear relationship between the fetal arterial glucose
concentration and cerebral blood flow and cerebral glucose and oxygen
uptakes. The electroencephalogram showed significant slowing with increases
in the cerebral metabolic rate. These findings suggest that fetal
hyperglycemia is associated with significant metabolic stimulation of the
brain.
