Sympathetic neural activation: an ordered affair
- 30 November 2010
- journal article
- Published by Wiley in Journal Of Physiology-London
- Vol. 588 (23), 4825-4836
- https://doi.org/10.1113/jphysiol.2010.195941
Abstract
Is there an ordered pattern in the recruitment of postganglionic sympathetic neurones? Using new multi-unit action potential detection and analysis techniques we sought to determine whether the activation of sympathetic vasomotor neurones during stress is governed by the size principle of recruitment. Multi-unit postganglionic sympathetic activity (fibular nerve) was collected from five male subjects at rest and during periods of elevated sympathetic stress (end-inspiratory apnoeas; 178 ± 37 s(mean ± S.D.)). Compared to baseline (0.24 ± 0.04 V), periods of elevated stress resulted in augmented sympathetic burst size (1.34 ± 0.38 V, P < 0.05). Increased burst size was directly related to both the number of action potentials within a multi-unit burst of postganglionic sympathetic activity (r = 0.88 ± 0.04, P < 0.001 in all subjects), and the amplitude of detected action potentials (r = 0.88 ± 0.06, P < 0.001 in all subjects). The recruitment of larger, otherwise silent, neurons accounted for approximately 74% of the increase in detected action potentials across burst sizes. Further, action potential conduction velocities (inverse of latencies) were increased as a function of action potential size (R² = 0.936, P = 0.001). As axon diameter is positively correlated with action potential size and conduction velocity, these data suggest that the principle of ordered recruitment based on neuronal size applies to postganglionic sympathetic vasomotor neurones. This information may be pertinent to our understanding of reflex-specific recruitment strategies in postganglionic sympathetic nerves, patterns of vasomotor control during stress, and the malleability of sympathetic neuronal properties and recruitment in health and disease.Keywords
This publication has 33 references indexed in Scilit:
- Spike detection in human muscle sympathetic nerve activity using a matched wavelet approachJournal of Neuroscience Methods, 2010
- Firing probability and mean firing rates of human muscle vasoconstrictor neurones are elevated during chronic asphyxiaJournal Of Physiology-London, 2010
- Altered firing pattern of single‐unit muscle sympathetic nerve activity during handgrip exercise in chronic heart failureJournal Of Physiology-London, 2009
- Hypercapnic vs. hypoxic control of cardiovascular, cardiovagal, and sympathetic functionAmerican Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2009
- Differing Pattern of Sympathoexcitation in Normal-Weight and Obesity-Related HypertensionHypertension, 2007
- Analysis of raw microneurographic recordings based on wavelet de-noising technique and classification algorithm: wavelet analysis in microneurographyIEEE Transactions on Biomedical Engineering, 2003
- Two sites for modulation of human sympathetic activity by arterial baroreceptors?Journal Of Physiology-London, 2001
- Arousal from sleep shortens sympathetic burst latency in humansJournal Of Physiology-London, 1999
- Peripheral nerve unmyelinated axons following lumbar sympathectomyAnnals of Neurology, 1981
- On optimal and data-based histogramsBiometrika, 1979