Temporal and spatial summation caused by aortic nerve stimulation in rabbits. Effects of stimulation frequencies and amplitudes

This study was designed to evaluate a possible central nervous system (CNS) component to acute baroreflex resetting. In nine arterial baroreceptor-denervated, chloralose-urethan-anesthetized rats, a control (C) aortic nerve stimulation curve (3-5 V, 1 ms, 0-64 Hz) was obtained. Next, a constant "baroreceptor" input was delivered to the CNS (left aortic nerve stimulation, 10 min, 10.2 +/- 1.5 Hz). Within the first 13 s of aortic nerve stimulation, maximum inhibition of lumbar sympathetic nerve activity (LSNA) was 60 +/- 7.8% of baseline and at 1 min it increased to 68 +/- 5.6% of baseline. At the end of the 10-min aortic nerve stimulation, LSNA was not different from the response at 1 min (68 +/- 5.6% = 74 +/- 4.1%). Immediately after the constant stimulation (within 30 s), a test or reset (RS) curve was obtained (0-64 Hz). A recovery (RC) curve was obtained 10-20 min later. The slope of the linear portion of the curve and the stimulation frequency that produced 50% maximum inhibition (ES50) were compared among the three baroreflex curves (C, RS, RC,) and no significant differences were found. Thus, although a CNS component to baroreflex adaptation was evident during the first minute of aortic nerve stimulation, a longer term acute resetting of the baroreflex curve did not occur.

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Acute resetting of baroreceptor reflex in rabbits: a central component

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1986.250.5.h866 ◽

1986 ◽

Vol 250 (5) ◽

pp. H866-H870 ◽

Cited By ~ 5

Author(s):

D. L. Kunze

Keyword(s):

Arterial Pressure ◽

Test Stimulus ◽

Nerve Stimulation ◽

Sympathetic Activity ◽

Constant Stimulus ◽

Baroreceptor Reflex ◽

Pressure Response ◽

Stimulus Period ◽

Aortic Nerve ◽

Stimulation Of

Electrical stimulation of the aortic nerve of the anesthetized rabbit was used to determine whether there is a central nervous system component to acute resetting of the baroreceptor reflex. After stimulation of the aortic nerve for 5 min at 10 Hz, a ramp test stimulus to the nerve produced a reflex arterial pressure response that was attenuated as compared with that produced by the same ramp prior to the five-min stimulation period. Renal sympathetic nerve activity was recorded simultaneously to determine whether a reduction in the magnitude of the reflex inhibition of sympathetic activity produced by the depressor nerve stimulation could account for the attenuated arterial pressure response. Renal activity during the test ramp was reduced to the same value both before and after the constant stimulus period and thus did not correlate with the attenuated pressure response. There was, however, prolonged inhibition of tonic sympathetic activity after the 5-min stimulus period such that during the test stimulus there was less sympathetic activity to inhibit. The results were similar when sympathetic activity was recorded from branches of the sciatic nerve and from thoracic postganglionic nerves. In these nerves the period of prolonged inhibition after aortic nerve stimulation was up to 5 min. The attenuated pressure response to baroreceptor nerve stimulation after a constant stimulus appears to reflect the reduced change in sympathetic activity rather than the value to which the sympathetic activity falls.

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Aortic nerve-activated cardioinhibitory neurons and interneurons

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.3.783 ◽

1975 ◽

Vol 229 (3) ◽

pp. 783-789 ◽

Cited By ~ 43

Author(s):

J Schwaber ◽

N Schneiderman

Keyword(s):

Vagus Nerve ◽

Nerve Stimulation ◽

Baroreceptor Reflex ◽

Motor Nucleus ◽

Vagus Nerves ◽

Antidromic Activation ◽

Medial Nucleus ◽

Aortic Nerve ◽

Dorsal Motor Nucleus ◽

Stimulation Of

Unit activity evoked by electrical stimulation of the aortic and vagus nerves was recorded in the dorsal motor nucleus and nucleus solitarius of unanesthetized rabbits. Cardioinhibitory cells which showed antidromic activation to stimulation of the vagus nerve and synaptic activation to stimulation of the aortic nerve were localized in lateral dorsal motor nucleus 0.5-0.8 mm anterior of the obex. Additionally, units were found that appeared to be interneurons in the medullary pathway subserving baroreceptor reflex effects on cardioinhibitory neurons. These cells were activated by aortic, and usually vagus, nerve stimulation, appeared to be polysynaptically activated, and were located in medial nucleus solitarius rostral to the obex. Neurons reflecting a cardiac rhythm but not activated by aortic nerve stimulation were also observed.

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Blood pressure response to aortic nerve stimulation in swine

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1968.215.6.1488 ◽

1968 ◽

Vol 215 (6) ◽

pp. 1488-1492 ◽

Cited By ~ 13

Author(s):

EM Schmidt

Keyword(s):

Blood Pressure ◽

Nerve Stimulation ◽

Blood Pressure Response ◽

Pressure Response ◽

Aortic Nerve

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Effect of racemic mixture and the (S+)-isomer of ketamine on temporal and spatial summation of pain

British Journal of Anaesthesia ◽

10.1093/bja/77.5.625 ◽

1996 ◽

Vol 77 (5) ◽

pp. 625-631 ◽

Cited By ~ 88

Author(s):

L Arendt-Nielsen ◽

J Nielsen ◽

S Petersen-Felix ◽

T W Schnider ◽

A M Zbinden

Keyword(s):

Spatial Summation ◽

Racemic Mixture ◽

Temporal And Spatial

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Effects of aortic nerve stimulation on cervical sympathetic preganglionic neurones in the rat

Brain Research ◽

10.1016/0006-8993(87)91182-6 ◽

1987 ◽

Vol 401 (1) ◽

pp. 190-194 ◽

Cited By ~ 5

Author(s):

Yoshinobu Numao ◽

Michael P. Gilbey

Keyword(s):

Nerve Stimulation ◽

Aortic Nerve ◽

Cervical Sympathetic

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Effect of expiratory loading on expiratory duration and pulmonary stretch receptor discharge

Journal of Applied Physiology ◽

10.1152/jappl.1986.61.5.1857 ◽

1986 ◽

Vol 61 (5) ◽

pp. 1857-1863 ◽

Cited By ~ 12

Author(s):

P. W. Davenport ◽

J. A. Wozniak

Keyword(s):

Linear Relationship ◽

Temporal Summation ◽

Spatial Summation ◽

Stretch Receptor ◽

Single Breath ◽

Stretch Receptors ◽

Pulmonary Stretch Receptors ◽

Temporal And Spatial ◽

Resistive Loads ◽

Pulmonary Stretch Receptor

Slowly adapting pulmonary stretch receptors have been hypothesized to be the afferents mediating the vagally dependent, volume-related prolongation of expiratory time (TE) during expiratory loading. It has been further suggested that the vagal component of this prolongation of TE is due to the temporal summation of pulmonary stretch receptor (PSR) activity during expiratory loading. This hypothesis was tested in rabbits exposed to resistive and elastic single-breath expiratory loading while PSR′s were simultaneously recorded. Both types of loads resulted in a decreased expired volume (VE) and increased expiratory duration (TE). The TE for resistive loads were significantly greater than for elastic loads for equivalent VE. Thus two different VE-TE relationships were found for resistive and elastic loads. When TE was plotted against the area under the expired volume trajectory, a single linear relationship was observed. PSR activity recorded during expiratory loading increased as VE decreased and TE increased. A single linear relationship resulted when the number of PSR spikes during the expiration was plotted against the associated TE for all types of loads. These findings demonstrate that the volume-related prolongation of TE with single-breath expiratory loads is associated with an increase in PSR discharge. These results support the hypothesis that the vagal component of load-dependent prolongation of TE is a function of both the temporal and spatial summation of PSR activity during the expiratory phase.

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