AJP - Heart and Circulatory Physiology, Vol 256, Issue 6 1659-H1666, Copyright © 1989 by American Physiological Society
Regional cerebral blood flow and glucose utilization during hypoglycemia in newborn dogs
D. J. Mujsce, M. A. Christensen and R. C. Vannucci
Department of Pediatrics, Pediatric Neurology and Neonatology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
To assess alterations in regional cerebral blood flow and glucose
utilization during perinatal hypoglycemia, newborn dogs (2-7 days postnatal
age) were anesthetized with halothane, tracheostomized, paralyzed, and
artificially ventilated with 70% N2O-30% O2 to maintain arterial normoxia
and normocapnia (arterial PO2 greater than 60 mmHg; arterial PCO2: 35-42
mmHg; arterial pH: 7.35-7.45). Regional cerebral blood flow (rCBF) and
glucose utilization (rCGU) were determined with iodo-[14C]antipyrine and
2-deoxy-[14C]glucose as the radioactive tracers, respectively. Hypoglycemia
with blood glucose concentrations averaging 0.9 mmol/l was achieved within
90-120 min in 10 animals using intermittent intravenous injections of
regular insulin; 10 control animals received 0.9% saline (blood glucose = 9
mmol/l). During hypoglycemia, mean arterial blood pressure was 81% of
control, whereas heart rate was unchanged. Arterial O2 and acid-base
balance were well maintained (arterial PO2 = 68 mmHg; PCO2 = 37 mmHg; pH =
7.35). Hypoglycemia was associated with significant increases in rCBF in
all of 16 analyzed structures, ranging from 172% (parietal white matter) to
249% (thalamus) of control values (17-65 ml.100 g-1.min-1). During
hypoglycemia, rCGU was relatively unchanged from normoglycemic values in 11
of 16 brain structures. Significant reductions in rCGU were seen only in
occipital white matter (-31%) and in the cerebellar vermis and hemisphere
(-31 and -43%, respectively). CGU actually increased slightly in the pons
and medulla (+12 and +19%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
