title: From supine to standing: in vivo segregation of myogenic and baroreceptor vasoconstriction in humans.
abstract: Myogenic vascular response is a form of systemic and regional vasoconstriction produced increasing the intra-arterial pressure by gravity. Here, the vasoconstriction due to the myogenic response, induced by the gravitational action in a dependent limb, is separated from that caused by the baroreceptor reflex. Regional changes of skin blood flow (SBF), total blood volume of the finger (TBVF), pulse pressure (PP), heart rate (HR), systolic, and diastolic blood pressure (BP) were analyzed in 10 healthy young subjects in supine and upright positions. By lowering the arm in supine position, SBF decreased compared to its basal measurement, PR increased, and PP contracted, indicating arterial vasoconstriction that rise BP TBVF increased, demonstrating an increment in venous volume. HR did not change, reflecting no action of the baroreceptor reflex. In upright position with lowered arm, there was an additional increase in BP variables, demonstrating vasoconstriction. Moreover, BP and HR showed oscillations at 0.1 Hz reflecting the entrance of the baroreceptor reflex. The action of gravity in a dependent limb in supine position induces a regional vasoconstriction and an increase of BP due to activation of the myogenic response, while the baroreceptor reflex or other neural factors do not appear to operate. In the upright position with the arm dependent, there is a further increase in regional vasoconstriction and BP with reciprocal changes in HR, indicating the entrance of the baroreceptor superimposed to the myogenic response. This study demonstrates that the myogenic and baroreceptor vasoconstriction can be separated in vivo.
authors.affiliation: Laboratorio de Neurofisiología Clínica, Departamento de Neurología y Psiquiatría, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.|Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Bruno
authors.initials: B
authors.lastname: Estañol
authors.affiliation: Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México City, México anarivera2000@gmail.com guillermo.delgadogr@uanl.edu.mx.|Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Ana Leonor
authors.initials: AL
authors.lastname: Rivera
authors.affiliation: Departamento de Instrumentación Electromecánica, Instituto Nacional de Cardiología, México City, México.
authors.forename: Raúl
authors.initials: R
authors.lastname: Martínez Memije
authors.affiliation: Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México City, México.|Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Ruben
authors.initials: R
authors.lastname: Fossion
authors.affiliation: Laboratorio de Neurofisiología Clínica, Departamento de Neurología y Psiquiatría, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.
authors.forename: Fermín
authors.initials: F
authors.lastname: Gómez
authors.affiliation: Laboratorio de Neurofisiología Clínica, Departamento de Neurología y Psiquiatría, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.
authors.forename: Katherine
authors.initials: K
authors.lastname: Bernal
authors.affiliation: Laboratorio de Neurofisiología Clínica, Departamento de Neurología y Psiquiatría, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.
authors.forename: Sofía
authors.initials: S
authors.lastname: Murúa Beltrán
authors.affiliation: Laboratorio de Neurofisiología Clínica, Departamento de Neurología y Psiquiatría, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México anarivera2000@gmail.com guillermo.delgadogr@uanl.edu.mx.|Departamento de Medicina Interna, Hospital Universitario "Dr. José Eleuterio González", Universidad Autónoma de Nuevo León, Monterrey, México.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Delgado-García
authors.affiliation: Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México City, México.|Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México City, México.|Colegio Nacional, México City, México.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Frank
mesh_terms: D000328:Adult; D017704:Baroreflex; D001794:Blood Pressure; D006112:Gravitation; D006339:Heart Rate; D006801:Humans; D011187:Posture; D012867:Skin / Q000098:blood supply; D016683:Supine Position; D014661:Vasoconstriction; D055815:Young Adult
keywords: Baroreflex vasoconstriction; baroreflex vasoconstriction; blood flow autoregulation; blood pressure autoregulation; myogenic vasoconstriction; segregation of myogenic