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Frequency-response characteristics of autonomic nervous system function in conscious rats
Journal article   Peer reviewed

Frequency-response characteristics of autonomic nervous system function in conscious rats

Harald M Stauss, Pontus B Persson, Alan Kim Johnson and Kevin C Kregel
The American journal of physiology, Vol.273(2 Pt 2), pp.H786-H795
08/1997
DOI: 10.1152/ajpheart.1997.273.2.h786
PMID: 9277496

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Abstract

To characterize the efferent pathway from the hypothalamic paraventricular nucleus (PVN) to peripheral autonomic neurons and finally to selected effector organs, we stimulated the PVN in 10 conscious rats at frequencies ranging from 0.05 to 2.0 Hz. Simultaneously, blood pressure, heart rate, splanchnic sympathetic nerve activity, and mesenteric artery blood flow were measured. The sinus node of the heart responded to PVN stimulation via the parasympathetic pathway (during beta 1-adrenergic blockade) up to a stimulation frequency of 2.0 Hz, whereas the sympathetically mediated response (during muscarinic blockade) was limited to stimulation frequencies < 0.5 Hz. The splanchnic nerve responded to PVN stimulation with synchronous discharges up to stimulation frequencies of 2.0 Hz, whereas the oscillatory component of the vasoconstrictor response of the mesenteric artery was negligible beyond stimulation frequencies of 1.0 Hz. We conclude that sympathetic transmission to the heart is at least four times slower than parasympathetic transmission. In addition, the time-limiting step in sympathetic transmission from the hypothalamus to vascular smooth muscle contraction and pacemaker activity of the sinus node may be located at the site of synaptic transmission to the adrenergic receptors.
Hemodynamics Animals Autonomic Nervous System - physiology Blood Vessels - physiology Electric Stimulation Heart Rate - physiology Male Parasympathetic Nervous System - physiology Paraventricular Hypothalamic Nucleus - physiology Rats Rats, Sprague-Dawley Splanchnic Nerves - physiology

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