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Variation of sympathetic reflex latency in man
J Fagius1, G Sundlöf, B G Wallin
1Department of Neurology, Akademiska Sjukhuset, University of Uppsala, Sweden.
Journal of the Autonomic Nervous System
|December 1, 1987
Summary
The heart beat and muscle sympathetic activity (MSA) latency shortens during maneuvers like Valsalva, deep breathing, and simulated diving. This suggests multiple central pathways regulate MSA baroreflex control.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Research
- Neuroscience
Background:
- Muscle sympathetic activity (MSA) exhibits a reflex relationship with the heart beat.
- The latency between heart beat and sympathetic bursts is typically stable at rest and independent of heart rate.
Purpose of the Study:
- To investigate the baroreflex regulation of muscle sympathetic activity (MSA).
- To determine if various physiological maneuvers alter the latency of the heart beat-sympathetic burst reflex.
Main Methods:
- Microelectrode recordings of peroneal nerve sympathetic activity in 35 healthy subjects.
- Measurements of latency changes during Valsalva maneuver, slow deep breathing, simulated diving, and pharmacological autonomic blockade.
Main Results:
- Valsalva maneuver reduced latency by 120 ms (P < 0.001).
- Slow deep breathing and simulated diving shortened latency by 60 ms (P < 0.001) and 80 ms (P < 0.05), respectively.
- Autonomic blockade (atropine and propranolol) increased latency by 70 ms (P < 0.001).
Conclusions:
- Findings suggest the baroreflex regulation of MSA involves more than one central pathway.
- Altered central processing time due to influences from various receptors may explain latency changes during different maneuvers.