Regional cerebral blood flow and glucose utilization during hypoglycemia in newborn dogs.
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)
Mujsce
D J
DJ
Department of Pediatrics, Pediatric Neurology and Neonatology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Christensen
M A
MA
Vannucci
R C
RC
D000818:Animals; D000831:Animals, Newborn; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000378:metabolism*; D004285:Dogs; D006339:Heart Rate; D006863:Hydrogen-Ion Concentration; D007003:Hypoglycemia / Q000503:physiopathology*; D007773:Lactates / Q000097:blood; D009928:Organ Specificity; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012016:Reference Values
D001786:Blood Glucose; D003837:Deoxy Sugars; D007773:Lactates; D002245:Carbon Dioxide; D003847:Deoxyglucose; D010100:Oxygen