Low-pressure-sensitive baroreceptor fibers recorded from rabbit carotid sinus nerves.
Title
Low-pressure-sensitive baroreceptor fibers recorded from rabbit carotid sinus nerves.
Creator
Qu L; Stuesse S L
Publisher
Circulation research
Date
1991
1991-12
Description
Activity was recorded from physiologically identified baroreceptor or chemoreceptor fibers in carotid sinus nerves of urethane-anesthetized spontaneously breathing rabbits. A carotid sinus area was vascularly isolated so that carotid sinus pressure and perfusion medium (Locke's solution or rabbit blood) could be controlled. The cervical sympathetic, vagus, and aortic depressor nerves were bilaterally cut to eliminate vagal and cardiopulmonary reflexes. Baroreceptor fibers could be divided into two groups: fibers with a mean firing threshold of 47.6 +/- 1.9 mm Hg and no activity below this threshold (37 fibers) and fibers that were active at low intrasinus pressures (18.1 +/- 2.2 impulses/sec at an intrasinus pressure of 0 mm Hg). The baroreceptor fibers that were spontaneously active at low pressures were also chemically sensitive: discharge rate was increased by 5-hydroxytryptamine (10 fibers, p less than 0.01), nicotine (10 fibers, p less than 0.01), or hypercapnia (13 fibers, p less than 0.001). The activity of baroreceptor fibers with a clear pressure threshold was usually decreased by hypercapnia (26 of 27 fibers, from 18.8 +/- 3.1 to 13.2 +/- 3.9 impulses/sec). Chemoreceptor fibers failed to respond to intrasinus pressure changes from 0 to 100 mm Hg (n = 25 fibers, p greater than 0.5) but were sensitive to chemical changes, as expected. Thus, there is a subset of baroreceptor fibers that, under certain conditions, is spontaneously active at very low intrasinus pressures and responds to changes in the chemical milieu.
Subject
Action Potentials; Animals; Blood Pressure; Carotid Sinus/*physiology; Hypercapnia/physiopathology; Hypoxia/physiopathology; Pressoreceptors/*physiology; Rabbits; Sympathetic Nervous System/physiology
Identifier
Rights
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Citation
Qu L; Stuesse S L, “Low-pressure-sensitive baroreceptor fibers recorded from rabbit carotid sinus nerves.,” NEOMED Bibliography Database, accessed May 10, 2024, https://neomed.omeka.net/items/show/4736.