Vasomotor reflexes to excitation of A? and C afferent fibers of the inferior cardiac nerve

1971 ◽  
Vol 71 (2) ◽  
pp. 99-101 ◽  
Author(s):  
V. L. Shur
Keyword(s):  
Cardiac Nerve ◽  
Afferent Fibers ◽  
Vasomotor Reflexes ◽  
Inferior Cardiac Nerve

Synchronization of cardiac-related discharges of sympathetic nerves with inputs from widely separated spinal segments

1995 ◽  
Vol 268 (6) ◽  
pp. R1472-R1483 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
S. M. Barman
Keyword(s):  
Phase Angle ◽  
Cervical Spinal Cord ◽  
Sympathetic Nerves ◽  
Time Interval ◽  
Renal Nerve ◽  
Cardiac Nerve ◽  
Spinal Segments ◽  
The Difference ◽  
Decerebrate Cats ◽  
Inferior Cardiac Nerve

We used phase spectral analysis to study the relationships between the cardiac-related discharges of pairs of postganglionic sympathetic nerves in urethan-anesthetized or decerebrate cats. Phase angle when converted to a time interval should equal the difference in conduction times from the brain to the nerves (i.e., transportation lag) if their cardiac-related discharges have a common central source. Transportation lag was estimated as the difference in the onset latencies of activation of the nerves by electrical stimulation of the medulla or cervical spinal cord. The phase angle for the cardiac-related discharges of two nerves was not always equivalent in time to the transportation lag. For example, in some cases the cardiac-related discharges of the renal nerve were coincident with or led those of the inferior cardiac nerve. In contrast, the electrically evoked responses of the renal nerve lagged those of the inferior cardiac nerve by > or = 32 ms. These observations are consistent with a model of multiple and dynamically coupled brain stem generators of the cardiac-related rhythm, each controlling a different sympathetic nerve or exerting nonuniform influences on different portions of the spinal sympathetic outflow.

Buffer reflexes, tolerance to ganglioplegics and their relationship to enhanced pressor responsiveness

1959 ◽  
Vol 197 (1) ◽  
pp. 217-222 ◽  
Author(s):  
Irvine H. Page ◽  
J. W. McCubbin
Keyword(s):  
Arterial Pressure ◽  
Evoked Potentials ◽  
Spontaneous Activity ◽  
Synaptic Activity ◽  
Carotid Occlusion ◽  
Cardiovascular Reflexes ◽  
Renal Nerves ◽  
Peripheral Sensitization ◽  
Cardiac Nerve ◽  
Inferior Cardiac Nerve

Tetraethylammonium, hexamethonium, chlorisondamine or mecamylamine suppressed the dog's carotid occlusion reflex well before appearance of maximum augmentation of responses to pressor drugs. The reflex usually returned to near control values despite continued administration of ganglioplegics, while augmented responsiveness persisted or became more marked. An antipseudocholinesterase or prostigmine restored the suppressed reflex without loss of augmented responsiveness. Electroneurographic measurements of efferent spontaneous activity in postganglionic renal nerves revealed synaptic pathways resistant to blockade: a small amount of activity persisted during tolerance to ganglioplegics and showed reflex changes. Similar measurements of spontaneous and evoked potentials in the inferior cardiac nerve showed no synaptic activity during tolerance. Augmentation of response to pressor drugs by ganglioplegics does not depend wholly upon loss of compensatory reflexes; peripheral sensitization is probably another mechanism concerned. Maintenance of arterial pressure and persistence of cardiovascular reflexes during tolerance to ganglioplegics appear to depend upon transmission of a relatively few impulses over pathways resistant to blockade and upon peripheral sensitization to the presumably smaller amounts of norepinephrine released from nerve endings.

Inferior cardiac nerve activity in the cat during occlusion of the mesenteric artery

1979 ◽  
Vol 236 (2) ◽  
pp. H286-H290
Author(s):  
R. S. Tuttle ◽  
M. McCleary
Keyword(s):  
Mesenteric Artery ◽  
Carotid Sinus ◽  
Artery Occlusion ◽  
Nerve Activity ◽  
Cardiac Nerve ◽  
Pressor Reflex ◽  
Depressor Reflex ◽  
Sympathetic Discharge ◽  
Mesenteric Artery Occlusion ◽  
Inferior Cardiac Nerve

A number of studies in this and other laboratories using hemodynamic and pharmacologic evidence have suggested that occlusion of the mesenteric artery evokes a pressor reflex initiated by mesenteric baroreceptors. To provide additional evidence in support of this hypothesis, neurophysiological recordings were made of inferior cardiac nerve activity during mesenteric artery occlusion (MAO). The results indicate that MAO enhances inferior cardiac nerve activity in the cat, providing that the carotid sinus nerves have been cut. Cutting of the mesenteric nerves further facilitates cardiac nerve activity and abolishes the response to mesenteric artery occlusion. The evidence suggests that MAO evokes a reflex sympathetic discharge which is subject to override by the carotid sinus depressor reflex. The afferent limb of the reflex is characterized by a tonic depressor outflow from the mesenteric pressure receptors.

Spinal interneurons with sympathetic nerve-related activity

1984 ◽  
Vol 247 (5) ◽  
pp. R761-R767 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Electrical Stimulation ◽  
Sympathetic Nerve ◽  
Sympathetic Neurons ◽  
Related Activity ◽  
Spinal Interneurons ◽  
The Third ◽  
Cardiac Nerve ◽  
Thoracic Spinal ◽  
Inferior Cardiac Nerve ◽  
Stimulation Of

This study tested the hypothesis that at least some brain stem and reflex control of sympathetic outflow is mediated over pathways containing spinal interneurons. The vicinity of the intermediolateral nucleus (IML) of the third thoracic spinal segment was searched for neurons with spontaneous activity correlated to that in the inferior cardiac post-ganglionic sympathetic nerve of 16 baroreceptor-denervated cats anesthetized with Dial-urethane. Section of the carotid sinus, aortic depressor, and vagus nerves prevented the coupling of sympathetic and nonsympathetic networks by pulse synchronous baroreceptor activity. Spike-triggered averaging revealed the existence of two types of spinal neurons with sympathetic nerve-related activity. Preganglionic sympathetic neurons (PSN; n = 33) were antidromically activated by electrical stimulation of their axons in the third thoracic white ramus. Four observations suggest that the second group of neurons with sympathetic nerve-related activity (n = 18) were spinal interneurons (SIN) in pathways that excite PSN. First, these neurons could not be antidromically activated by stimulation of the segmental white ramus. Second, the intervals between spontaneous unit spike occurrence and inferior cardiac nerve activity were similar for SIN and PSN. Third, SIN and PSN were activated with nearly identical onset latencies by electrical stimulation of medullary sympathoexcitatory sites. Fourth, SIN were excited by intensities of cardiac sympathetic afferent stimulation that also activated PSN and the inferior cardiac nerve. SIN and PSN were distinguished on the basis of their spontaneous firing patterns; i.e., interspike intervals of SIN were significantly shorter than those of PSN.(ABSTRACT TRUNCATED AT 250 WORDS)

Caudal ventrolateral medullary neurons are elements of the network responsible for the 10-Hz rhythm in sympathetic nerve discharge

1994 ◽  
Vol 72 (1) ◽  
pp. 106-120 ◽  
Author(s):  
S. M. Barman ◽  
H. S. Orer ◽  
G. L. Gebber
Keyword(s):  
Firing Rate ◽  
Sympathetic Nerve ◽  
Pressor Response ◽  
Ventral Surface ◽  
Frequency Domain Analysis ◽  
Nerve Activity ◽  
Cardiac Nerve ◽  
Spike Triggered Averaging ◽  
Inferior Cardiac Nerve ◽  
Nerve Discharge

1. This is the first study to show that caudal ventrolateral medullary (CVLM) neurons play an important role in governing the 10-Hz rhythm in sympathetic nerve discharge (SND). Spike-triggered averaging showed that the naturally occurring discharges of 66 of 246 CVLM neurons located 0–2.5 mm rostral to the obex, 4–4.25 mm lateral to the midline, and within 2 mm of the ventral surface were correlated to the 10-Hz rhythm in inferior cardiac SND of 17 urethan-anesthetized cats. 2. Frequency domain analysis was used to characterize further the relationships between SND and the discharges of 45 CVLM neurons with activity correlated to the 10-Hz rhythm in inferior cardiac nerve activity. The autospectra of the discharges of 22 of these neurons contained a sharp peak near 10 Hz (corresponding to the peak in the autospectra of SND), although the mean firing rate of these neurons was only 5.9 +/- 0.5 (SE) spikes/s. The peak coherence value relating the 10-Hz discharges of these CVLM neurons and the inferior cardiac nerve was 0.42 +/- 0.03. The autospectra for the other 23 CVLM neurons did not contain a peak near 10 Hz. Their mean firing rate was 2.3 +/- 0.5 spikes/s, and the peak coherence value relating their discharges to the 10-Hz rhythm in SND was 0.08 +/- 0.01. The coherence value was significantly different than zero in all but three cases. 3. Importantly, spike-triggered averaging and coherence analysis demonstrated that CVLM neurons with activity correlated to the 10-Hz rhythm did not have activity correlated 1:1 to the cardiac-related rhythm in SND of baroreceptor-innervated cats. Also, their discharges were not correlated to the irregular 2- to 6-Hz oscillations in SND of baroreceptor-denervated cats. These data support the hypothesis that different pools of brain stem neurons generate the 10-Hz rhythm and the 2- to 6-Hz oscillations (or cardiac-related rhythm) in SND. 4. Despite the fact that CVLM neurons with activity correlated to the 10-Hz rhythm did not have activity correlated 1:1 to the cardiac-related rhythm in SND, these neurons were influenced by baroreceptor afferent nerve activity. First, their firing rates could be decreased (n = 12) or increased (n = 2) during the pressor response induced by inflating a balloon in the aorta (aortic obstruction). Second, on occasion, the discharges of CVLM neurons and the 10-Hz rhythm in SND were entrained to a harmonic of the heart rate.(ABSTRACT TRUNCATED AT 400 WORDS)

Categories of axons in the inferior cardiac nerve of the cat

1978 ◽  
Vol 177 (2) ◽  
pp. 301-310 ◽  
Author(s):  
Dennis G. Emery ◽  
Robert D. Foreman ◽  
Richard E. Coggeshall
Keyword(s):  
Cardiac Nerve ◽  
Inferior Cardiac Nerve
Sign in / Sign up

Export Citation Format

Share Document