1327 REGIONAL CEREBRAL BLOOD FLOW IN THE NEWBORN BABOON

To evaluate possible use of the newborn baboons in physiologic and parmacologic studies on cerebral blood flow (rCBF), 6 pre- and near- term newborn baboons, were studied within 2 hrs. following a C-section birth. Mean gestational age was 160/184 days (range 149-168 d) and mean birth weight was 0.89 kg (range 0.69 - 1.06 kg). Polyvinyl catheters were placed on the left ventricle via internal carotid artery, abdominal aorta via femoral artery, and sagittal or internal jugular vein. A magnetic flow probe was also placed around the internal carotid artery. rCBF was measured using 1 of 3 radiolabelled microspheres (141Ce 51Cr 85Sr) wi(:h simultaneous determination of arterial and venous blood gases, glucose, lactates, and hemoglobin. The result show that under stable and controlled conditions, the rCBF to 16 different brain regions examined varied considerably. rCBF (ml/100g/min) was maximal in cerebellar peduncles (86.3 ± 21.0) and medulla (70.9 ± 10.8 ml/100g/min). Lesser flow was observed at pons (67. ± 6.7) cerebellum (41.1 ± 9.2), sup. and inf. colliculi (35.0 ± 6.6), thalamus (29.4 ± 7.3), parietotemporal lobes (29.1 ± 11.2) and frontal lobe (20.6 ± 4.2). A positive correlation was noted between rCBF and O2 consumption showing that metabolically active brain regions are better perfused. No correlation between rCBF and gestational age or birth weight was noted suggesting that rCBF does not change substantially during the last quarter of gestations.