Selective blockade of AT1 receptor attenuates impairment of hypotensive autoregulation and improves cerebral blood flow after brain injury in the newborn pig

摘要: Background Fluid percussion injury (FPI) in piglets produces vasoconstriction of pial arteries (PAs), decreases cerebral blood flow (CBF), and impairment hypotensive autoregulation. Two types angiotensin II receptors, AT1 AT2, have been identified the brain. This study characterized effect pretreatment with AT1- AT2-selective antagonists on CBF autoregulation after FPI. Methods was induced chloralose-anesthetized newborn pigs equipped closed cranial windows. determined by radiolabeled microsphere technique. Results Moderate severe hypotension (71 +/- 3, 53 2, 40 1 mmHg for normotension, moderate hypotension, respectively) elicited PA dilation without changes sham control piglets. The antagonist ZD 7155 partially restored impaired hypotension-induced FPI (19 34 vs. 5 7 12 20 3% during control, FPI, + animals, respectively). also blunted reductions normotension observed untreated animals (43 4, 38 5, 55 3 32 19 27 5% pretreated AT2 selective PD 123,319 did not restore prevent Conclusion These data indicate that blockade receptor diminished reduction decrease as well further suggest activation contributes to cerebrovascular dysregulation