Increased platelet-activating factor-induced periventricular brain microvascular constriction associated with immaturity

ing factor-induced periventricular brain microvascular con-striction associated with immaturity. Am J Physiol Regul Integr Comp Physiol 284: R928–R935, 2003; 10.1152/ ajpregu.00633.2002.—Oxidant stress contributes to the pathogenesis of hypoxic-ischemic encephalopathies. Platelet-activating factor (PAF) is generated during oxidant stress. We studied the vasomotor mode of actions of PAF on periven-tricular (PV) microvessels of fetal (75 % of term), newborn (1–3 days), and adult pigs. PAF constricted PV microvessels from fetal (29.27 2.6%) and newborn (22.14 3.2%) pigs but was ineffective in adults (2.5%). Specific [3H]PAF bind-ing was greater in fetus and newborn than in adults; a concordant developmental PAF-induced inositol phosphate formation was observed. PAF-induced vasoconstriction was abrogated by thromboxane A2 (TXA2) synthase and recepto