Analysis of Neural Contributions to Ultradian Oscillations of Blood Pressure and Heart Rate in Dogs

A remarkably stable and accurate FM telemetry system was used to obtain long-term recordings of mean arterial pressure (MAP) and heart rate (HR) from unanesthetized, free-running dogs. These data were analyzed for their harmonic content by applying standard Fast Fourier Transform (FFT) time series analysis techniques. The FFT coefficients were used to calculate power spectral density functions from which the primary oscillatory frequency and the associated power of the primary frequency were determined. Initial studies revealed coherent ultradian oscillations of MAP and HR with a period between 1-2 hours (hr). These oscillations were found to be in phase. The significant decrease in power of these oscillations following the administration of clonidine, a centrally acting alpha$\sb2$ agonist, suggested that the central nervous system was involved in the genesis of these rhythms. Peripheral ganglionic blockade induced by hexamethonium bromide (10mg/kg/hr) significantly reduced the power of both MAP and HR oscillations, demonstrating the contribution of the autonomic efferent nerves. Atropine sulfate (2mg/hr) potentiated the power of both MAP and HR oscillations (P $<$ 0.06) suggesting that vagal efferent nerves are not mediating either HR or MAP oscillations, and may actually attenuate them. Metoprolol (200mg/day; b.i.d. for 5 days), a beta$\sb1$ antagonist, significantly decreased the power of HR and MAP oscillations. Prazosin (50ug/kg/hr), an alpha$\sb1$ antagonist, significantly decreased the power of MAP oscillations but increased the power of HR oscillations. These latter two series suggest that sympathetic innervation of both the vasculature and the heart are involved in expressing these rhythms.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Broten, Theodore Paul

Contributors dc:contributor

• Zehr, John E.

• Biology, Animal Physiology

Identifier

(UMI)AAI8802987

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71451