Regional Cerebral Blood Flow in the Newborn Beagle Pup: the Germinal Matrix is a “Low-Flow” Structure

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Abstract
Summary: The newborn beagle pup serves as a model for neonatal intraventricular hemorrhage (IVH). Fluctuations in germinal matrix blood flow are felt to play a major role in the pathogenesis of IVH. We studied regional cerebral blood flow in awake newborn beagle pups utilizing [14C]-iodoantipyrine as a blood flow indicator and quantitative autoradiography. The equilibrium [tissue]:[blood] partition coefficient for iodoantipyrine was 1.13 ± .06 for grey matter. Blood flow was calculated for cerebral cortex (frontal = 59 ± 9 ml/100 g/min), 14 subcortical nuclear structures (e.g., caudate = 45 ± 6 ml/100 g/min), 3 white matter structures (centrum semiovale = 7 ± 1 ml/100 g/min), and germinal matrix (7 ± 1 ml/100 g/min) (mean ± S.E.). We conclude that under normal physiologic conditions the germinal matrix receives relatively low blood flow. This information can be used for comparison with germinal matrix blood flow during adverse experimental conditions. Speculation: wLow baseline blood flow may place the germinal matrix at risk for ischemic injury during hypoxic or hypotensive stress. This ischemic injury may be a critical step in the pathogenesis of intraventricular hemorrhage, either by disrupting vascular integrity or by producing a disproportionate increase in germinal matrix blood flow (luxury perfusion) after reestablishment of normoxemia and normotension.