Relative Roles of the Sympathetic and Parasympathetic Nervous Systems in the Reflex Control of Heart Rate
Why the study?
Does sympathetic or parasympathetic blockade alter the reflex heart rate response to acute changes in arterial pressure in dogs and humans?
Population
22 anesthetized dogs, 4 trained unanesthetized dogs, and 4 intact unanesthetized human subjects
Comparison
Acute changes in arterial pressure via… vs Control state
Design
Preclinical
Authors
Discussion
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Implication
Challenges reciprocal autonomic model of baroreflex; hypothesis-generating for human translation and requires clinical validation.
Structured PICO
Does sympathetic or parasympathetic blockade alter the reflex heart rate response to acute changes in arterial pressure in dogs and humans?
P
Population
22 anesthetized dogs (23 experiments), 4 trained unanesthetized dogs, and 4 intact unanesthetized human subjects
I
Intervention
Acute changes in arterial pressure via phenylephrine or nitroglycerin, combined with sympathetic blockade (guanethidine, pronethalol, nethalide) or parasympathetic blockade (atropine, vagotomy)
C
Comparator
Control state (responses to pressure changes without autonomic blockade)
O
Outcome
Reflex alterations of heart rate consequent to changes in arterial pressuresurrogate
The reflex decrease in heart rate from elevated arterial pressure is mediated by the parasympathetic nervous system, while the reflex increase from lowered pressure is mediated primarily by the sympathetic nervous system, challenging the traditional concept of simultaneous reciprocal changes.
Cite This Study
Glick et al. (1965) studied this question.