Coupled oscillators account for the slow rhythms in sympathetic nerve discharge and phrenic nerve activity

1997 ◽  
Vol 272 (4) ◽  
pp. R1314-R1324 ◽  
Author(s):  
S. Zhong ◽  
S. Y. Zhou ◽  
G. L. Gebber ◽  
S. M. Barman
Keyword(s):  
Phrenic Nerve ◽  
Sympathetic Nerve ◽  
Coupled Oscillators ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Slow Rhythm ◽  
Nerve Discharge

Phase-locked slow rhythms in sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) are generally thought to arise from a common brain stem "cardiorespiratory" oscillator. The results obtained in vagotomized and baroreceptor-denervated cats anesthetized with pentobarbital sodium do not support this view. First, partial coherence analysis revealed that the discharges of pairs of sympathetic nerves remained correlated at the frequency of the central respiratory cycle after mathematical removal of the portion of these signals common to PNA. The residual coherence suggests that the slow rhythm in SND is dependent on central mechanisms in addition to those responsible for rhythmic PNA. Second, the rhythms in SND and PNA became coupled in a 2:1 relationship during either moderate systemic hypocapnia or hypercapnia. Third, the slow rhythm in SND was maintained when rhythmic PNA was eliminated during extreme hypocapnia. Fourth, during extreme hypercapnia, coherence of the rhythms in SND and PNA was drastically reduced. These results suggest that the slow rhythms in SND and PNA arise from separate oscillators that are normally coupled.

Sympathetic rhythms during hyperventilation-induced apnea

1985 ◽  
Vol 249 (4) ◽  
pp. R424-R431 ◽  
Author(s):  
C. A. Connelly ◽  
R. D. Wurster
Keyword(s):  
Phrenic Nerve ◽  
Sympathetic Nerve ◽  
Sympathetic Activity ◽  
Sympathetic Nerves ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Spectral Peaks ◽  
Respiratory Modulation

The effect of hyperventilation-induced apnea on the respiratory rhythmicity of sympathetic nerve activity was determined using spectral analysis of sympathetic nerve frequencies. Left phrenic, external intercostal, and inferior cardiac sympathetic nerves were recorded in alpha-chloralose-anesthetized, vagotomized, paralyzed, artificially ventilated cats. The respiratory modulation of sympathetic activity during normoventilation was indicated by spectral peaks of sympathetic activity coinciding with respiratory frequencies determined from the phrenic nerve activity of each cat. The spectral peaks of respiratory-related sympathetic activity disappeared during hyperventilation-induced apnea and then reappeared with the return of phrenic nerve activity when normoventilation was resumed. Although sympathetic activity lost its respiratory modulation during hyperventilation, baroreceptor-mediated bilateral carotid occlusion responses and electrocardiogram (R wave)-triggered computer summation of cardiac related sympathetic activity were unaffected. Hence central respiratory inputs on sympathetic pathways in the central nervous system best explain the origin of respiratory-related sympathetic rhythms. Independent sympathetic rhythms of apparent nonrespiratory origin may be due to artificial ventilator influences, baroreflex-autonomic oscillation loops, or Mayer waves.

Partial Spectral Analysis of Cardiac-Related Sympathetic Nerve Discharge

2000 ◽  
Vol 84 (3) ◽  
pp. 1168-1179 ◽  
Author(s):  
Peter D. Larsen ◽  
Craig D. Lewis ◽  
Gerard L. Gebber ◽  
Sheng Zhong
Keyword(s):  
Sympathetic Nerve ◽  
Phase Locking ◽  
Sympathetic Nerves ◽  
Heart Beat ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Clear Peak ◽  
The Relationship ◽  
Mode Of Coordination ◽  
Nerve Discharge

We have studied the relationship between pulse synchronous baroreceptor input (represented by the arterial pulse, AP) and the cardiac-related rhythm in sympathetic nerve discharge (SND) of urethan-anesthetized cats by using partial autospectral and partial coherence analysis. Partial autospectral analysis was used to mathematically remove the portion of SND that can be directly attributed to the AP, while partial coherence analysis was used to removed the portion of the relationship between the discharges of sympathetic nerve pairs that can be attributed to linear AP-SND relationships that are common to the nerves. The ordinary autospectrum of SND (ASSND) and coherence functions relating the discharges of nerve pairs (CohSND-SND) contained a peak at the frequency of the heart beat. When the predominant mode of coordination between AP and SND was a phase walk, partialization of the autospectra of SND with AP (ASSND/AP) left considerable power in the cardiac-related band. In contrast, when the predominant mode of coordination between AP and SND was phase-locking, there was virtually no cardiac-related activity remaining in ASSND/AP. Partialization of CohSND-SND with AP reduced the peak coherence within the cardiac-related band in both modes of coordination but to a much greater extent during phase-locking. After baroreceptor denervation, CohSND-SND at the cardiac frequency remained significant, although a clear peak above background coherence was no longer apparent. These results are consistent with a model in which the central circuits controlling different sympathetic nerves share baroreceptor inputs and in addition are physically interconnected. The baroreceptor-sympathetic relationship contains both linear and nonlinear components, the former reflected by phase-locking and the latter by phase walk. The residual power in ASSND/AP during phase walk can be attributed to the nonlinear relationship, and the residual peak in partialized nerve-to-nerve coherence (CohSND-SND/AP) arises largely from nonlinearities that are common to the two nerves. During both phase walk and phase-locking, in addition to common nonlinear AP-SND relationships, coupling of the central circuits generating the nerve activities may contribute to CohSND-SND/APbecause significant CohSND-SND was still observed following baroreceptor denervation.

Basis for synchronization of sympathetic and phrenic nerve discharges

1976 ◽  
Vol 231 (5) ◽  
pp. 1601-1607 ◽  
Author(s):  
SM Barman ◽  
GL Gebber
Keyword(s):  
Respiratory Rate ◽  
Phrenic Nerve ◽  
Phase Relations ◽  
Nerve Activity ◽  
Slow Oscillations ◽  
Phrenic Nerve Activity ◽  
The Relationship ◽  
Made In ◽  
Nerve Discharge

The basis for the relationship between the discharges in the external cartized cats that were vagotomized, paralyzed, and artificially ventilated. Ive discharge (with the period of the cycle of phrenic nerve activity) is extrinsically imposed on central sympathetic networks by elements of the brainstem respiratory oscillator. However, a number of observations made in the present study contradict this view. First, changes in respiratory rate were accompanied by dramatic shifts in the phase relations between sympathetic and phrenic nerve discharge. Second, slow oscillations of sympathetic and phrenic nerve discharge were not always locked in a 1:1 relation. Third, the slow sympathetic rhythm persisted when respiratory rhythmicity disappeic components of sympathetic and phrenic nerve activity are generated by in

Coordination of the cardiac-related discharges of sympathetic nerves with different targets

1994 ◽  
Vol 267 (2) ◽  
pp. R400-R407 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
S. M. Barman ◽  
H. S. Orer
Keyword(s):  
Heart Rate ◽  
Coherence Function ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Arterial Pulse ◽  
Nerve Activity ◽  
Multiple Routes ◽  
Rate Frequency ◽  
Decerebrate Cats

Partial coherence analysis was used to remove the influences of pulse-synchronous baroreceptor nerve activity (as reflected by the arterial pulse) on the coherence of the cardiac-related discharges of sympathetic nerve pairs in unanesthetized decerebrate cats. It can be predicted that the peak at the heart rate frequency in the ordinary coherence function relating the discharges of two nerves will be eliminated by either partialization using the arterial pulse or surgical baroreceptor denervation, if the central circuits controlling the nerves share baroreceptor inputs but are not interconnected. Contrary to this prediction, in many experiments the peak was not eliminated by partialization using the arterial pulse. Moreover, partialization often nonuniformly reduced the peaks at the heart rate frequency in the coherence functions for different nerve pairs. These results are consistent with a model of multiple routes over which baroreceptor influences are distributed to the central circuits controlling different sympathetic nerves. Specifically, we propose that the direct route from the baroreceptors to each of the central circuits is complemented by cross talk among the central circuits.

Regulation of the sympathetic nerve discharge bursting pattern during heat stress

1998 ◽  
Vol 275 (6) ◽  
pp. R1992-R2001 ◽  
Author(s):  
Michael J. Kenney ◽  
Dale E. Claassen ◽  
Michelle R. Bishop ◽  
Richard J. Fels
Keyword(s):  
Heat Stress ◽  
Frequency Domain ◽  
Phrenic Nerve ◽  
Sympathetic Nerve ◽  
Core Body Temperature ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Frequency Components ◽  
Pattern Transformation ◽  
Nerve Discharge

Frequency-domain analyses were used to determine the effect of heat stress on the relationships between the discharge bursts of sympathetic nerve pairs and sympathetic and phrenic nerve pairs in chloralose-anesthetized rats. Sympathetic nerve discharge (SND) was recorded from the renal, splanchnic, splenic, and lumbar nerves during increases in core body temperature (Tc) from 38 to 41.4 ± 0.3°C. The following observations were made: 1) hyperthermia transformed the cardiac-related bursting pattern of SND to a pattern that contained low-frequency, non-cardiac-related bursts, 2) the pattern transformation was uniform in regionally selective sympathetic nerves, 3) hyperthermia enhanced the frequency-domain coupling between SND and phrenic nerve bursts, and 4) low-frequency SND bursts recorded during hyperthermia contained significantly more activity than cardiac-related bursts. We conclude that acute heat stress profoundly affects the organization of neural circuits responsible for the frequency components in sympathetic nerve activity and that SND pattern transformation provides an important strategy for increasing the level of activity in sympathetic nerves during increased Tc.

Differential relationships among the 10-Hz rhythmic discharges of sympathetic nerves with different targets

1994 ◽  
Vol 267 (2) ◽  
pp. R387-R399 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
S. M. Barman ◽  
Y. Paitel ◽  
H. S. Orer
Keyword(s):  
Brain Stem ◽  
Cross Talk ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Sharp Peak ◽  
Coherence Analysis

Partial coherence analysis was used to remove the influences of the central circuits controlling a sympathetic nerve (as reflected by its discharges) on the coherence of the 10-Hz discharges of other sympathetic nerves in unanesthetized decerebrate or urethan-anesthetized cats. In many cases, partialization reduced but did not eliminate the sharp peak near 10 Hz in the coherence functions relating the discharges of sympathetic nerve pairs. This observation implies that the central sources of the 10-Hz rhythmic discharges of any nerve are not identical to those responsible for the rhythm recorded from any other nerve. Partial coherence analysis also revealed differential relationships among the 10-Hz rhythmic discharges of sympathetic nerves with different targets. Importantly, the pattern of differential relationships observed in one experiment could be the reverse of that in the next. Although the basis for the differential relationships is not yet clear, nonuniform coupling of multiple brain stem 10-Hz oscillators and/or nonuniform cross talk between spinal circuits controlling different sympathetic nerves may be involved.

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