title: Role of the sympathetic nervous system in cerebrovascular responses to air-jet stress in rats.
abstract: This study examined the role of sympathetic nerves in the control of cerebral hemodynamics during air-jet stress. In adult male Sprague-Dawley rats, blood flow velocity (pulsed Doppler) was measured in both internal carotid arteries 1 week after excision of one superior cervical ganglion. Blood pressure (BP) and carotid blood flows (CBFs) were simultaneously recorded during exposure to air-jet stress. In 5 out of 13 rats, stress was applied after β(2)-adrenoceptor blockade with ICI 118551 (0.4 mg/kg, then 0.2 mg/kg/h, i.v). Stress evoked an immediate rise in BP, CBFs, and vascular conductances. Vasodilatation was much larger on the denervated side than on the intact side (mean ± SEM: 78 ± 7 versus 19 ± 4%; P < 0.02) and lasted about 10 s. Thereafter, blood flows returned to or near normal and showed parallel variations while BP remained elevated. There was, therefore, a net vasoconstriction on both sides. In ICI 118551-treated rats, the initial vasodilatation was not significantly reduced on the denervated side (64 ± 4%), but the subsequent vasoconstriction was enhanced (P < 0.05) on both sides. In conclusion, air-jet stress evokes an immediate, short-lasting vasodilatation through a mechanism unrelated to β(2)-adrenoceptor stimulation. Sympathetic nerves powerfully limit this phenomenon, and thus contribute to protect the cerebral circulation from stress-induced BP surges.
authors.affiliation: Unité de Neurocardiologie, Faculté de Pharmacie, Université Lyon 1, F-69008 Lyon, France.
authors.forename: Aurélia
authors.initials: A
authors.lastname: Revel
authors.forename: Valérie
authors.initials: V
authors.lastname: Oréa
authors.forename: Bruno
authors.initials: B
authors.lastname: Chapuis
authors.forename: Christian
authors.initials: C
authors.lastname: Barrès
authors.forename: Claude
authors.initials: C
authors.lastname: Julien
mesh_terms: D058672:Adrenergic beta-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000503:physiopathology*; D017783:Superior Cervical Ganglion / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction
chemical_list: D058672:Adrenergic beta-2 Receptor Antagonists; D011412:Propanolamines; C026777:ICI 118551