title: Sleep-dependent changes in the coupling between heart period and arterial pressure in newborn lambs.
abstract: This study assessed whether sleep-dependent changes in the relationship between heart period (HP) and mean arterial pressure (MAP) occur in newborn life. Electrodes for electrocorticographic, electromyographic, and electrooculographic monitoring and an arterial catheter for blood pressure recordings were implanted in 11 newborn lambs. HP and MAP beat-to-beat values were computed from 120-s blood pressure recordings during quiet wakefulness, active sleep, and quiet sleep. For each recording, the time shift at which the maximum of the HP versus MAP cross-correlation function was attained was identified. For each lamb and wake-sleep state, an average correlation coefficient was then computed corresponding to the median value of such time shifts. The maximum of the cross-correlation function was attained with HP lagging behind MAP. The corresponding mean correlation coefficient was significantly higher in quiet sleep (0.51 +/- 0.05) than either in quiet wakefulness (0.31 +/- 0.05) or in active sleep (0.29 +/- 0.03). Sleep-related differences in the correlation between HP and MAP were maintained after HP and MAP data were low-pass filtered at 0.3 Hz to remove their fast ventilatory oscillations. In conclusion, data indicate that the relationship between spontaneous fluctuations in HP and those in MAP is sleep-state dependent in newborn lambs. A positive HP versus MAP correlation with HP lagging behind MAP is consistent with baroreflex control of HP. Heart rhythm thus may be more tightly controlled by the baroreceptor reflex and less dependent on central autonomic commands in quiet sleep than either in quiet wakefulness or in active sleep.
authors.affiliation: Dipartimento di Fisiologia Umana e Generale, Università di Bologna, Piazza di Porta San Donato, 2 40127 Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Silvani
authors.forename: Valentina
authors.initials: V
authors.lastname: Asti
authors.forename: Tijana
authors.initials: T
authors.lastname: Bojic
authors.forename: Vera
authors.initials: V
authors.lastname: Ferrari
authors.forename: Carlo
authors.initials: C
authors.lastname: Franzini
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Lenzi
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Grant
authors.forename: Adrian M
authors.initials: AM
authors.lastname: Walker
authors.forename: Giovanna
authors.initials: G
authors.lastname: Zoccoli
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002319:Cardiovascular System; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D012756:Sheep; D012890:Sleep; D013997:Time Factors