title: Effect of pregnancy and nitric oxide on the myogenic vasodilation of posterior cerebral arteries and the lower limit of cerebral blood flow autoregulation.
abstract: Hemorrhage during parturition can lower blood pressure beyond the lower limit of cerebral blood flow (CBF) autoregulation that can cause ischemic brain injury. However, the impact of pregnancy on the lower limit of CBF autoregulation is unknown. We measured myogenic vasodilation, a major contributor of CBF autoregulation, in isolated posterior cerebral arteries (PCAs) from nonpregnant and late-pregnant rats (n = 10/group) while the effect of pregnancy on the lower limit of CBF autoregulation was studied in the posterior cerebral cortex during controlled hemorrhage (n = 8). Pregnancy enhanced myogenic vasodilation in PCA and shifted the lower limit of CBF autoregulation to lower pressures. Inhibition of nitric oxide synthase (NOS) prevented the enhanced myogenic vasodilation during pregnancy but did not affect the lower limit of CBF autoregulation. The shift in the autoregulatory curve to lower pressures during pregnancy is likely protective of ischemic injury during hemorrhage and appears to be independent of NOS.
authors: Neuroscience Graduate Program, University of Vermont College of Medicine, Burlington, VT 05405, USA.
authors: Abbie C
authors: AC
authors: Chapman
authors: Marilyn J
authors: MJ
authors: Cipolla
authors: Siu-Lung
authors: SL
authors: Chan
mesh_terms: D000818:Animals; D062186:Arterial Pressure; D002545:Brain Ischemia / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006470:Hemorrhage / Q000378:metabolism / Q000503:physiopathology; D006706:Homeostasis; D007022:Hypotension / Q000378:metabolism / Q000503:physiopathology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D020769:Posterior Cerebral Artery / Q000378:metabolism / Q000503:physiopathology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase
keywords: CBF autoregulation; hypotension; myogenic vasodilation; nitric oxide; pregnancy