Frequency characteristics of sympathetic nerve discharge in anesthetized rats

1994 ◽  
Vol 267 (3) ◽  
pp. R830-R840 ◽  
Author(s):  
M. J. Kenney
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Sympathetic Nerve ◽  
Acute Stress ◽  
Sympathetic Nerves ◽  
Frequency Characteristics ◽  
Total Power ◽  
Dynamic Nature ◽  
Frequency Components ◽  
Nerve Discharge

Frequency-domain analyses were used to characterize basal sympathetic nerve discharge (SND) and to determine the relationships between the activity recorded simultaneously from sympathetic nerves in chloralose-anesthetized, baroreceptor-innervated rats. Discharges were recorded from the splanchnic, renal, and lumbar nerves. The following observations were made. 1) Approximately 65-75% of total power in SND was contained below 9 Hz in either baroreceptor-innervated rats or baroreceptor-denervated rats. 2) Coherence values relating the activity of two nerves were significantly different from zero within this frequency band. 3) The interval between the discharges of two sympathetic nerves was either frequency dependent or constant within the coherent frequency band. 4) The frequency components of SND and the relationships between the activity in two sympathetic nerves could be altered during periods of acute stress. These results suggest that the system responsible for basal SND in rats is composed of either multiple sympathetic generators or multiple filters arranged in parallel, which are capable of producing different outputs. The dynamic nature of these circuits was revealed by the changes that occurred during periods of acute stress.

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.

Relationships between activity of sympathetic nerve pairs: phase and coherence

1990 ◽  
Vol 259 (3) ◽  
pp. R549-R560 ◽  
Author(s):  
B. Kocsis ◽  
G. L. Gebber ◽  
S. M. Barman ◽  
M. J. Kenney
Keyword(s):  
Frequency Band ◽  
Sympathetic Nerve ◽  
Coherence Function ◽  
Sympathetic Nerves ◽  
Phase Spectrum ◽  
Central System ◽  
Functional States ◽  
Alpha Chloralose ◽  
Constant Interval ◽  
Nerve Discharge

The coherence function and phase spectrum were used to study the relationships between the discharges of sets of two postganglionic or preganglionic sympathetic nerves in baroreceptor-denervated cats anesthetized with either 5,5-diallylbarbiturate-urethan or alpha-chloralose. Most of the power in sympathetic nerve discharge was contained between 2 and 6 Hz. The coherence values relating the activity of two nerves were significantly different from zero within this frequency band. The phase spectrum was either linear or complex (i.e., showed changes in slope) within the coherent frequency band. We observed three patterns of relationship. The first pattern was characterized by a constant interval between activity in different sympathetic nerves within the coherent frequency band. The second pattern was characterized by a frequency-dependent interval. The third pattern was characterized by uncoupling of the 2- to 6-Hz rhythms in the discharges of different nerves. Switching between these patterns was observed. We suggest that the three patterns reflect different functional states of the central system responsible for the 2- to 6-Hz rhythm. Two models of this system are entertained. The first model is one of a system of coupled oscillators while filtering circuits that receive common inputs are the elements of the second model.

Paraventricular nucleus bicuculline alters frequency components of sympathetic nerve discharge bursts

2001 ◽  
Vol 281 (3) ◽  
pp. H1233-H1241 ◽  
Author(s):  
Michael J. Kenney ◽  
Mark L. Weiss ◽  
Kaushik P. Patel ◽  
Yan Wang ◽  
Richard J. Fels
Keyword(s):  
Paraventricular Nucleus ◽  
Sympathetic Nerve ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Receptor Antagonism ◽  
Gaba Agonist ◽  
Frequency Components ◽  
Induced Changes ◽  
Nerve Discharge

Autospectral and coherence analyses were used to determine the effect of paraventricular nucleus (PVN) GABAA receptor antagonism [microinfusion or microinjections of bicuculline methiodide (BMI) 100 pmoles] on sympathetic nerve discharge (SND) frequency components (bursting pattern and relationships between discharges in regionally selective nerves) in α-chloralose-anesthetized rats. SND was recorded from the renal, splenic, and lumbar nerves. The following observations were made. First, PVN BMI microinjections, but not PVN saline or cortical BMI microinjections, transformed the cardiac-related SND bursting pattern in baroreceptor-innervated rats to one characterized by the presence of low-frequency bursts not synchronized to the cardiac cycle or phrenic nerve discharge bursts. Second, SND pattern changes were similar in the renal, splenic, and lumbar nerves, and peak coherence values relating low-frequency bursts in sympathetic nerve pairs (renal-splenic, renal-lumbar, and splenic-lumbar) were significantly increased from preinjection control after PVN BMI microinjection. Third, PVN BMI microinjections significantly increased the coupling between low-frequency SND bursts in baroreceptor-denervated rats. Finally, PVN BMI-induced changes in the SND bursting pattern were not observed after PVN pretreatment with muscimol (GABA agonist, 1 nmole). We conclude that PVN GABAA receptor antagonism profoundly alters the frequency components in sympathetic nerves.

scholarly journals The posterior vermis of the cerebellum selectively inhibits 10-Hz sympathetic nerve discharge in anesthetized cats

2009 ◽  
Vol 297 (1) ◽  
pp. R210-R217 ◽  
Author(s):  
Susan M. Barman ◽  
Gerard L. Gebber
Keyword(s):  
Sympathetic Nerve ◽  
Cortical Neurons ◽  
Fold Increase ◽  
Total Power ◽  
Chemical Inactivation ◽  
Naturally Occurring ◽  
Functional Implications ◽  
Frequency Components ◽  
Nerve Discharge

We studied the changes in inferior cardiac sympathetic nerve discharge (SND) and mean arterial pressure (MAP) produced by aspiration or chemical inactivation (muscimol microinjection) of lobule IX (uvula) of the posterior vermis of the cerebellum in baroreceptor-denervated and baroreceptor-innervated cats anesthetized with urethane. Autospectral analysis was used to decompose SND into its frequency components. Special attention was paid to the question of whether the experimental procedures affected the rhythmic (10-Hz and cardiac-related) components of SND. Aspiration or chemical inactivation of lobule IX produced an approximately three-fold increase in the 10-Hz rhythmic component of SND ( P ≤ 0.05) in baroreceptor-denervated cats. Total power (0- to 20-Hz band) was unchanged. Despite the absence of a change in total power in SND, there was a statistically significant increase in MAP. In baroreceptor-innervated cats, neither aspiration nor chemical inactivation of the uvula caused a significant change in cardiac-related or total power in SND or MAP. These results are the first to demonstrate a role of cerebellar cortical neurons of the posterior vermis in regulating the frequency composition of naturally occurring SND. Specifically, these neurons selectively inhibit the 10-Hz rhythm-generating network in baroreceptor-denervated, urethane-anesthetized cats. The functional implications of these findings are discussed.

Differential relationships among discharges of postganglionic sympathetic nerves

1991 ◽  
Vol 260 (6) ◽  
pp. R1159-R1167 ◽  
Author(s):  
M. J. Kenney ◽  
S. M. Barman ◽  
G. L. Gebber ◽  
S. Zhong
Keyword(s):  
Frequency Band ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
The Body ◽  
Spectral Analyses ◽  
Decerebrate Cats ◽  
Nerve Discharge

The relationships among the simultaneously recorded discharges of as many as four postganglionic sympathetic nerves were studied with coherence and phase spectral analyses in baroreceptor-denervated cats. Discharges were recorded from the inferior cardiac (CN), vertebral (VN), and renal (RN) nerves. Most of the power in sympathetic nerve discharge was less than 6 Hz, and the discharges of any two nerves coherred over a frequency band generally between 0 and 15 Hz. Peak coherence occurred between 2 and 6 Hz in most cases. Our most important observations are as follows. 1) Coherence values were significantly higher in chloralose-anesthetized than in unanesthetized decerebrate cats. 2) Coherence values were higher for near ipsilateral nerves (e.g., CN and VN) than for widely separated ipsilateral nerves (e.g., CN and RN). 3) Coherence values for most pairs were higher when the nerves were located on the same side (ipsilateral nerves) rather than on opposite sides (contralateral nerves) of the body. 4) Coherence values were higher for some functionally complementary nerves (e.g., CN and RN) than for noncomplementary nerves (e.g., VN and RN). These results support the hypothesis that the central circuits responsible for the basal discharges of different postganglionic sympathetic nerves are selectively coupled.

Effects of brain stem lesions on 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge

1992 ◽  
Vol 262 (6) ◽  
pp. R1015-R1024 ◽  
Author(s):  
S. Zhong ◽  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Brain Stem ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Ventrolateral Medulla ◽  
Total Power ◽  
Field Potentials ◽  
Brain Stem Lesions ◽  
Stem Lesions ◽  
Nerve Discharge

We studied the effects of brain stem lesions or transection on the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge (SND) in baroreceptor-denervated unanesthetized decerebrate cats. The results indicate that these two rhythms depend in part on different brain stem regions. The 10-Hz rhythm was eliminated by ablation of the rostral ventrolateral medulla (RVLM), medullary raphe complex, or pontine parabrachial and Kolliker-Fuse complex (PB/KF) or by pontomedullary border transection. Except for RVLM lesions, these procedures did not disrupt the 2- to 6-Hz rhythm in SND. In fact the power in SND at frequencies less than 6 Hz was increased by raphe or PB/KF lesions. Total power in SND was not significantly affected by raphe or PB/KF lesions, but mean arterial pressure was significantly reduced. Field potentials recorded from the RVLM (11 of 26 sites) and raphe (10 of 20 sites) were correlated to the 10-Hz rhythm in SND, further supporting a role of these areas in either generating or relaying this rhythm to sympathetic nerves. In contrast, field potentials recorded from the PB/KF were not correlated to the 10-Hz rhythm in SND. Thus this region may provide a tonic drive to the 10-Hz generator located elsewhere in the brain stem.

The 10-Hz rhythm in sympathetic nerve discharge

1992 ◽  
Vol 262 (6) ◽  
pp. R1006-R1014 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber ◽  
S. Zhong
Keyword(s):  
Frequency Domain ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Frequency Dependent ◽  
New Findings ◽  
Decerebrate Cats ◽  
Nerve Discharge

Frequency-domain analysis was used to characterize the relationships among the rhythmic discharges recorded simultaneously from two to four sympathetic nerves in unanesthetized decerebrate cats. The major new findings were as follows. 1) The 10-Hz rhythmic discharges of different nerves cohered strongly in baroreceptor-innervated and -denervated cats. 2) The interval between the discharges of two nerves was frequency dependent in the 10-Hz band in some cats, supporting the view that the 10-Hz rhythm is generated by multiple central circuits that are coupled. 3) In some cases the central circuits responsible for the 10-Hz rhythms nonuniformly affected different nerves. 4) In baroreceptor-innervated cats the coherence values for the cardiac-related discharges of any two nerves were significantly higher than those for the 10-Hz rhythms. 5) In baroreceptor-denervated cats the 10-Hz rhythmic discharges of different nerves cohered more strongly than the 2- to 6-Hz rhythms. 6) The 10-Hz rhythm usually was not a harmonic of the 2- to 6-Hz or cardiac-related rhythm. Thus these rhythms are generated independently.

Bispectral analysis of complex patterns of sympathetic nerve discharge

1996 ◽  
Vol 271 (5) ◽  
pp. R1173-R1185 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
Y. Paitel
Keyword(s):  
Sympathetic Nerve ◽  
Phase Locking ◽  
Nonlinear Coupling ◽  
Cardiac Sympathetic Nerve ◽  
Bispectral Analysis ◽  
Frequency Locking ◽  
Linear Superposition ◽  
Frequency Components ◽  
Complex Patterns ◽  
Nerve Discharge

Bispectral analysis was used to demonstrate quadratic nonlinear coupling (i.e., phase locking) of different frequency components in inferior cardiac sympathetic nerve discharge (SND) of urethan-anesthetized rats. The complex patterns of SND analyzed included mixtures of 1) the cardiac-related and 10-Hz rhythms, 2) the 10-Hz rhythm and irregular 2-to 6-Hz oscillations, and 3) the 10-Hz rhythm and a lower frequency non-cardiac-related rhythm near 4 Hz. In some cases, the bicoherence function (normalized bispectrum) showed no phase locking of these frequency components. Cases of nil bicoherence are equated with linear superposition of frequency components, which implies the existence of multiple and noninteractive central circuits. Increased complexity of SND was observed in other cases, as evidenced by significant phase locking of different frequency components with or without frequency locking. Frequency locking (higher frequency rhythm is a multiple of lower) was confirmed by constructing Lissajous orbital plots showing covariation of voltages in selectively filtered bands of SND. We equate frequency locking with nonlinear coupling of the central generators of different sympathetic nerve rhythms and phase locking without frequency locking possibly with nonlinearities arising at levels below noncoupled central rhythm generators.

Brain stem neuronal types with activity patterns related to sympathetic nerve discharge

1981 ◽  
Vol 240 (5) ◽  
pp. R335-R347 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Brain Stem ◽  
Sympathetic Nerve ◽  
Activity Patterns ◽  
Sympathetic Nerves ◽  
Eeg Activity ◽  
Spike Triggered Averaging ◽  
Neuronal Types ◽  
Discharge Patterns ◽  
Electroencephalogram Eeg ◽  
Nerve Discharge

The relationships among the spontaneous activity of single neurons in the cat medulla and inferior cardiac sympathetic nerve discharge (SND), electroencephalogram (EEG) activity, phrenic nerve activity, and the R wave of the electrocardiogram were studied with the methods of spike-triggered averaging and postevent interval analysis. Three categories of neurons (SR, SE, and S) with activity patterns related to SND wee identified. The activity of SR units was related in time to SND and the R wave but not to EEG activity. SE unit discharges were related to SND and EEG activity but not to the R wave. S unit activity was related only to SND. Each of the three categories of neurons could be subdivided into two groups depending on whether their discharges were followed by an increase or a decrease in SND. All unit types exhibited respiratory-related discharge patterns. These data are discussed with regard to the problems associated with the identification of neurons in brain stem networks that govern the discharges of sympathetic nerves.

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