scholarly journals Human muscle sympathetic nerve activity and plasma noradrenaline kinetics in space

2002 ◽  
Vol 538 (1) ◽  
pp. 321-329 ◽  
Author(s):  
Andrew C. Ertl ◽  
André Diedrich ◽  
Italo Biaggioni ◽  
Benjamin D. Levine ◽  
Rose Marie Robertson ◽  
...  
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Human Muscle ◽  
Plasma Noradrenaline ◽  
Nerve Activity

A signal-averaging technique for the analysis of human muscle sympathetic nerve activity

1992 ◽  
Vol 73 (1) ◽  
pp. 376-381 ◽  
Author(s):  
C. L. Birkett ◽  
C. A. Ray ◽  
E. A. Anderson ◽  
R. F. Rea
Keyword(s):  
Data Collection ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Human Muscle ◽  
Hard Copy ◽  
Signal Acquisition ◽  
Signal Averaging ◽  
Nerve Activity ◽  
Averaging Technique

We present a signal-averaging technique for analysis of human muscle sympathetic nerve activity (SNA). Nerve traffic was averaged by coupling signal acquisition to electrocardiographic R waves. The amplitude of the averaged waveform was multiplied by the number of R waves sampled to provide a measure of SNA in arbitrary units. This was compared with SNA measured by manual digitization of hard-copy records. In nine volunteers, SNA was increased or decreased with stepwise infusions of nitroprusside or phenylephrine: there were 10 5-min periods of data in each subject. Across all subjects, the correlation between manual and signal-averaged measures of SNA was excellent during both nitroprusside (r = 0.98) and phenylephrine infusions (r = 0.91) and the slopes of the regression lines were near unity. In three periods of data collection, electrical artifacts were added randomly at frequencies of 0.5 and 0.07 Hz during playback of the signal into the computer. Signal-averaged estimates of SNA were unaffected by artifacts. This technique provides reliable observer-independent measures of SNA.

Relationship between size and latency of action potentials in human muscle sympathetic nerve activity

2011 ◽  
Vol 105 (6) ◽  
pp. 2830-2842 ◽  
Author(s):  
Aryan Salmanpour ◽  
Lyndon J. Brown ◽  
Craig D. Steinback ◽  
Charlotte W. Usselman ◽  
Ruma Goswami ◽  
...  
Keyword(s):  
Action Potential ◽  
Sympathetic Nerve ◽  
Action Potentials ◽  
Sympathetic Nerve Activity ◽  
Lower Body Negative Pressure ◽  
Burst Size ◽  
Muscle Sympathetic Nerve Activity ◽  
Peak Height ◽  
Human Muscle ◽  
Nerve Activity

We employed a novel action potential detection and classification technique to study the relationship between the recruitment of sympathetic action potentials (i.e., neurons) and the size of integrated sympathetic bursts in human muscle sympathetic nerve activity (MSNA). Multifiber postganglionic sympathetic nerve activity from the common fibular nerve was collected using microneurography in 10 healthy subjects at rest and during activation of sympathetic outflow using lower body negative pressure (LBNP). Burst occurrence increased with LBNP. Integrated burst strength (size) varied from 0.22 ± 0.07 V at rest to 0.28 ± 0.09 V during LBNP. Sympathetic burst size (i.e., peak height) was directly related to the number of action potentials within a sympathetic burst both at baseline ( r = 0.75 ± 0.13; P < 0.001) and LBNP ( r = 0.75 ± 0.12; P < 0.001). Also, the amplitude of detected action potentials within sympathetic bursts was directly related to the increased burst size at both baseline ( r = 0.59 ± 0.16; P < 0.001) and LBNP ( r = 0.61 ± 0.12; P < 0.001). In addition, the number of detected action potentials and the number of distinct action potential clusters within a given sympathetic burst were correlated at baseline ( r = 0.7 ± 0.1; P < 0.001) and during LBNP ( r = 0.74 ± 0.03; P < 0.001). Furthermore, action potential latency (i.e., an inverse index of neural conduction velocity) was decreased as a function of action potential size at baseline and LBNP. LBNP did not change the number of action potentials and unique clusters per sympathetic burst. It was concluded that there exists a hierarchical pattern of recruitment of additional faster conducting neurons of larger amplitude as the sympathetic bursts become stronger (i.e., larger amplitude bursts). This fundamental pattern was evident at rest and was not altered by the level of baroreceptor unloading applied in this study.

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