title: Partial pharmacologic blockade shows sympathetic connection between blood pressure and cerebral blood flow velocity fluctuations.
abstract: Cerebral autoregulation (CA) dampens transfer of blood pressure (BP)-fluctuations onto cerebral blood flow velocity (CBFV). Thus, CBFV-oscillations precede BP-oscillations. The phase angle (PA) between sympathetically mediated low-frequency (LF: 0.03-0.15Hz) BP- and CBFV-oscillations is a measure of CA quality. To evaluate whether PA depends on sympathetic modulation, we assessed PA-changes upon sympathetic stimulation with and without pharmacologic sympathetic blockade. In 10 healthy, young men, we monitored mean BP and CBFV before and during 120-second cold pressor stimulation (CPS) of one foot (0°C ice-water). We calculated mean values, standard deviations and sympathetic LF-powers of all signals, and PAs between LF-BP- and LF-CBFV-oscillations. We repeated measurements after ingestion of the adrenoceptor-blocker carvedilol (25mg). We compared parameters before and during CPS, without and after carvedilol (analysis of variance, post-hoc t-tests, significance: p<0.05). Without carvedilol, CPS increased BP, CBFV, BP-LF- and CBFV-LF-powers, and shortened PA. Carvedilol decreased resting BP, CBFV, BP-LF- and CBFV-LF-powers, while PAs remained unchanged. During CPS, BPs, CBFVs, BP-LF- and CBFV-LF-powers were lower, while PAs were longer with than without carvedilol. With carvedilol, CPS no longer shortened resting PA. Sympathetic activation shortens PA. Partial adrenoceptor blockade abolishes this PA-shortening. Thus, PA-measurements provide a subtle marker of sympathetic influences on CA and might refine CA evaluation.
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: max.hilz@uk-erlangen.de.
authors.forename: Max J
authors.initials: MJ
authors.lastname: Hilz
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: ruihao.wang@uk-erlangen.de.
authors.forename: Ruihao
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, Addiction, Psychotherapy and Psychosomatics, Klinikum am Europakanal, Am Europakanal 71, 91056 Erlangen, Germany. Electronic address: haraldmarthol@gmx.net.
authors.forename: Harald
authors.initials: H
authors.lastname: Marthol
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: mao.liu@uk-erlangen.de.
authors.forename: Mao
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: alexatillmann@web.de.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Tillmann
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: stephan_riss@yahoo.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Riss
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: paulina@paulina-hauck.com.
authors.forename: Paulina
authors.initials: P
authors.lastname: Hauck
authors.affiliation: Department of Psychiatry and Psychotherapy, Paracelsus Medical University Nuremberg, Prof.-Ernst-Nathan-Strasse 1, 90419 Nuremberg, Germany. Electronic address: katharina.hoesl@klinikum-nuernberg.de.
authors.forename: Katharina M
authors.initials: KM
authors.lastname: Hösl
authors.affiliation: Department of Cardiology, Klinik Neustadt a. d. Aisch, Paracelsusstraße 30-36, 91413 Neustadt a. d. Aisch, Germany. Electronic address: gerald.wasmeier@kliniken-nea.de.
authors.forename: Gerald
authors.initials: G
authors.lastname: Wasmeier
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Bayer HealthCare, Bayer Pharma AG, Global Development Specialty Medicine, Müllerstr. 178, Building P300, Room 239, 13353 Berlin, Germany. Electronic address: brigitte.stemper@bayer.com.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Stemper
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany. Electronic address: martin.koehrmann@uk-erlangen.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Köhrmann
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D001795:Blood Pressure Determination; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology; D003080:Cold Temperature; D000081005:Cyclohexane Monoterpenes; D064368:Healthy Volunteers; D006339:Heart Rate / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D008297:Male; D039821:Monoterpenes / Q000494:pharmacology*; D011312:Pressure; D013564:Sympathetic Nervous System / Q000502:physiology*; D013565:Sympatholytics / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D013565:Sympatholytics; C075856:carveol
keywords: Blood pressure; Cerebral blood flow velocity; Pharmacologic stress; Phase angle; Sympathetic nerve activity