1441 PERINATAL REGIONAL CEREBRAL BLOOD FLOW (rCBF): EFFECT OF THEOPHYLLINE

Abstract

Theophylline (T) is known to produce cerebral vasoconstriction in both animals and humans. It is unclear whether these effects vary regionally, especially in the developing brain. Using the tracer iodo-[C] antipyrine and the indicator-fractionation technique described by Cavazutti and Duffy, we studied rCBF in awake newborn dogs (3 to 9 days old), treated with either saline (n=4) or T (n=3).Catheters were placed in the right common carotid artery and the right external jugular vein while under halothane anesthesia. Following a 4 hour recovery period, either T, 45 mg/kg, or saline was administered by slow IV infusion. After an additional 1 hour equilibration period, the rCBF measurement was performed. pCO2, measured just prior to rCBF determination, was 36 ± 3 mm Hg (mean ± S.D.) in the saline group and 26 ± 6 mm Hg in the T group. T levels in treated animals equaled 38 ± 4 μg/ml.RCBF in the saline group ranged from 6 ml/100 gm/min in sub-cortical white matter to 75 ml/100g/min in the oculomotor n. nucl. T treated dogs, when compared to saline treated dogs, had lower values in all 28 areas of the brain analyzed. Thalamic and midbrain nuclei showed the greatest reductions (35-48%). At the other extreme, medullary and cerebellar structures showed little reduction (7-16%) with T. Though exceptions were noted, the degree of T associated reduction in rCBF generally paralleled reported newborn dog CO2 - CBF sensitivity.