title: Frequency of slow oscillations in arterial pressure and R-R intervals during muscle metaboreflex activation.
abstract: Altered frequency of slow (0.04-0.15Hz) arterial pressure and R-R interval oscillations has been observed in various diseases but the mechanisms for this frequency shift are unclear. The median (Med) frequencies of slow R-R interval and blood pressure (BP) oscillations were recorded in 11 healthy subjects with paced breathing (0.25Hz) during muscle metaboreflex and baroreflex mediated sympathetic stimuli: 1) handgrip exercise (HG) followed by post-exercise circulatory occlusion (PECO), 2) handgrip exercise during ischemia by circulatory occlusion (IHG) and 3) passive head-up tilt (TILT). Med(BP) shifted to the higher frequency during HG, PECO and IHG (from 0.070+/-0.009Hz to 0.088+/-0.013, 0.085+/-0.015 and 0.099+/-0.013Hz, respectively, p<0.01 for all) but not during TILT (0.078+/-0.012Hz). Similarly, Med(R-R) shifted to the higher frequency during HG, PECO and IHG (from 0.072+/-0.009Hz to 0.085+/-0.014, 0.085+/-0.016 and 0.095+/-0.015Hz, respectively, p<0.01 for all) but not during TILT (0.075+/-0.012Hz). Med(BP) and Med(R-R) were higher during IHG compared to HG and lower during TILT compared to both HG and IHG (p<0.01 for all). We conclude that the sympathetic stimulus induced by muscle metaboreflex is an important mechanism increasing the frequency of slow oscillations in arterial pressure and R-R intervals. The present results give new insight to understand the physiology underlying the frequency of slow arterial pressure and R-R interval oscillations.
authors.affiliation: Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland. Antti.Kiviniemi@verve.fi <Antti.Kiviniemi@verve.fi>
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.forename: Suvi
authors.initials: S
authors.lastname: Tiinanen
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
authors.forename: Tapio
authors.initials: T
authors.lastname: Seppänen
authors.forename: Timo H
authors.initials: TH
authors.lastname: Mäkikallio
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
mesh_terms: D000328:Adult; D000465:Algorithms; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination; D002320:Cardiovascular Physiological Phenomena; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D009132:Muscles / Q000098:blood supply / Q000378:metabolism / Q000502:physiology*; D012018:Reflex / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted