Cardiac sympathetic premotor neurons

1997 ◽  
Vol 272 (2) ◽  
pp. R615-R620 ◽  
Author(s):  
R. R. Campos ◽  
R. M. McAllen
Keyword(s):  
Injection Site ◽  
Neuronal Cell ◽  
Sympathetic Nerves ◽  
Ventrolateral Medulla ◽  
Response Ratio ◽  
Cardiac Nerve ◽  
Neuronal Cell Bodies ◽  
Premotor Neurons ◽  
Sympathetic Premotor Neurons ◽  
Inferior Cardiac Nerve

To locate premotor neurons controlling the cardiac sympathetic supply and to determine their relation to brain stem vasomotor pathways, the rostral ventrolateral medulla (RVLM) was mapped in seven chloralose-anesthetized cats, with the use of microinjections of sodium glutamate (5-10 nl, 0.1 M) to excite neuronal cell bodies. Cardiac sympathetic responses were recorded from the ipsilateral inferior cardiac nerve, while recordings were made simultaneously from postganglionic vasoconstrictor fibers to skeletal muscle (ipsilateral peroneal nerve). Baroreceptors were denervated to eliminate the reflex effects of blood pressure changes. Most of the 115 injected RVLM sites excited both sympathetic nerves. Inferior cardiac nerve activity increased by up to 395% (mean 105 +/- 86%, SD), and muscle vasoconstrictor activity increased by up to 487% (110 +/- 107%). Their relative response varied with injection site, however. For 16 of the most rostromedial injections, the inferior cardiac nerve-to-muscle vasoconstrictor response ratio exceeded that expected by two- to sevenfold; for 9 very caudolateral injections that ratio was strongly reversed, favoring muscle vasoconstrictors by two to fivefold. Intervening sites gave more equal responses. Overall, the response ratio varied systematically with injection site. These findings demonstrate that neurons with preferential or selective actions on the cardiac sympathetic outflow are present in the RVLM and are organized topographically. The simplest interpretation is that a population of selective cardiac sympathetic premotor neurons occupies a territory substantially overlapping, but centered rostromedially to, the population controlling vasoconstriction in muscle.

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.

Tonic drive to sympathetic premotor neurons of rostral ventrolateral medulla from caudal pressor area neurons

1999 ◽  
Vol 276 (4) ◽  
pp. R1209-R1213 ◽  
Author(s):  
R. R. Campos ◽  
R. M. McAllen
Keyword(s):  
Blood Pressure ◽  
Significant Proportion ◽  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Cervical Cord ◽  
Neuron Activity ◽  
Tonic Activity ◽  
Premotor Neurons ◽  
Sympathetic Premotor Neurons ◽  
Caudal Pressor

The responses of sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM) to activation or inactivation of neurons in the caudal pressor area (CPA) were studied in urethan-anesthetized rats. Extracellular recordings were made from 32 barosensitive single units in the RVLM, of which 26 were antidromically activated from the cervical cord. Unilateral microinjections ofl-glutamate (0.5–5 nmol) into the CPA increased firing in 13 of 14 premotor neurons by 90 ± 30% while raising blood pressure. Both ipsilateral and contralateral injections were effective. Unilateral or bilateral inhibition of CPA neuron activity by microinjecting glycine (5–200 nmol/side) lowered blood pressure, while it reduced firing in 9 of 10 and 16 of 17 premotor neurons, respectively, by 45 ± 9 and 39 ± 6%. A significant proportion of tonic activity in RVLM sympathetic premotor neurons is thus driven, directly or indirectly, by neurons in the CPA.

Fractal Activity Generated Independently by Medullary Sympathetic Premotor and Preganglionic Sympathetic Neurons

2003 ◽  
Vol 90 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Hakan S. Orer ◽  
Mahasweta Das ◽  
Susan M. Barman ◽  
Gerard L. Gebber
Keyword(s):  
Spinal Cord ◽  
Power Law ◽  
Time Scale ◽  
Sympathetic Neurons ◽  
Fano Factor ◽  
Ventrolateral Medulla ◽  
Interspike Intervals ◽  
Antidromic Activation ◽  
Premotor Neurons ◽  
Sympathetic Premotor Neurons

In anesthetized cats with cervical spinal cord transection, Fano factor analysis was used to test for time-scale invariant (fractal) fluctuations in spike counts of single preganglionic cervical sympathetic neurons (PSNs) and putative sympathetic premotor neurons located in the rostral ventrolateral medulla (RVLM) and caudal medullary raphe. The medullary neurons exhibited cardiac-related activity, and their axons projected to the spinal cord, as demonstrated by antidromic activation. The variance-to-mean spike count ratio (Fano factor) was plotted as a function of the window size used to count spikes. The Fano factor curves for seven PSNs, eight RVLM neurons, and eight raphe neurons contained a power law relationship extending over more than one time scale. In these cases, random shuffling of the interspike intervals in the original time series eliminated the power law relationship. Thus the power law relationships can be attributed to long-range correlations among interspike intervals rather than simply to the distribution of the intervals that is not changed by shuffling the data. It is concluded that PSNs and sympathetic premotor neurons in the medulla can independently generate fractal firing patterns.

scholarly journals Prostate innervation and local anesthesia in prostate procedures

2002 ◽  
Vol 57 (6) ◽  
pp. 287-292 ◽  
Author(s):  
Alexandre Oliveira Rodrigues ◽  
Marcos Tobias Machado ◽  
Eric Roger Wroclawski
Keyword(s):  
Local Anesthesia ◽  
Risk Group ◽  
Transrectal Ultrasound ◽  
Neuronal Cell ◽  
Sympathetic Nerves ◽  
High Risk Group ◽  
Sensory Innervation ◽  
Prostatic Biopsy ◽  
Neuronal Cell Bodies ◽  
Pelvic Ganglia

The nerve supply of the human prostate is very abundant, and knowledge of the anatomy contributes to successful administration of local anesthesia. However, the exact anatomy of extrinsic neuronal cell bodies of the autonomic and sensory innervation of the prostate is not clear, except in other animals. Branches of pelvic ganglia composed of pelvic (parasympathetic) and hypogastric (sympathetic) nerves innervate the prostate. The autonomic nervous system plays an important role in the growth, maturation, and secretory function of this gland. Prostate procedures under local anesthesia, such as transurethral prostatic resections or transrectal ultrasound-guided prostatic biopsy, are safe, simple, and effective. Local anesthesia can be feasible for many special conditions including uncomplicated prostate surgery and may be particularly useful for the high-risk group of patients for whom inhalation or spinal anesthesia is inadvisable.

Descending vasomotor pathways from the dorsomedial hypothalamic nucleus: role of medullary raphe and RVLM

2004 ◽  
Vol 287 (4) ◽  
pp. R824-R832 ◽  
Author(s):  
J. Horiuchi ◽  
R. M. McAllen ◽  
A. M. Allen ◽  
S. Killinger ◽  
M. A. P. Fontes ◽  
...  
Keyword(s):  
Firing Rate ◽  
Acute Stress ◽  
Ventrolateral Medulla ◽  
Hypothalamic Nucleus ◽  
Modest Contribution ◽  
Medullary Raphe ◽  
Premotor Neurons ◽  
Dorsomedial Hypothalamic Nucleus ◽  
Sympathetic Premotor Neurons ◽  
Raphe Pallidus

The dorsomedial hypothalamic nucleus (DMH) is believed to play a key role in mediating vasomotor and cardiac responses evoked by an acute stress. Inhibition of neurons in the rostral ventrolateral medulla (RVLM) greatly reduces the increase in renal sympathetic nerve activity (RSNA) evoked by activation of the DMH, indicating that RVLM neurons mediate, at least in part, the vasomotor component of the DMH-evoked response. In this study, the first aim was to determine whether neurons in the medullary raphe pallidus (RP) region also contribute to the DMH-evoked vasomotor response, because it has been shown that the DMH-evoked tachycardia is mediated by the RP region. The second aim was to directly assess the effect of DMH activation on the firing rate of RVLM sympathetic premotor neurons. In urethane-anesthetized rats, injection of the GABAA receptor agonist muscimol (but not vehicle solution) in the RP region caused a modest (∼25%) but significant reduction in the increase in RSNA evoked by DMH disinhibition (by microinjection of bicuculline). In other experiments, disinhibition of the DMH resulted in a powerful excitation (increase in firing rate of ∼400%) of 5 out of 6 spinally projecting barosensitive neurons in the RVLM. The results indicate that neurons in the RP region make a modest contribution to the renal sympathoexcitatory response evoked from the DMH and also that sympathetic premotor neurons in the RVLM receive strong excitatory inputs from DMH neurons, consistent with the view that the RVLM plays a key role in mediating sympathetic vasomotor responses arising from the DMH.

Kainic acid on the rostral ventrolateral medulla inhibits phrenic output and CO2 sensitivity

1988 ◽  
Vol 65 (4) ◽  
pp. 1525-1534 ◽  
Author(s):  
E. E. Nattie ◽  
J. W. Mills ◽  
L. C. Ou ◽  
W. M. St John
Keyword(s):  
Kainic Acid ◽  
Neuronal Cell ◽  
Ventral Surface ◽  
Ventrolateral Medulla ◽  
Co2 Response ◽  
Specific Amino Acid ◽  
Amino Acid Receptors ◽  
Neuronal Cell Bodies ◽  
Chemosensitive Areas ◽  
End Tidal

We used the neurotoxin, kainic acid, which is known to stimulate neuronal cell bodies as opposed to axons of passage by binding to specific amino acid receptors to determine whether cells with such receptors have access to the ventrolateral medullary surface and are involved in central ventilatory chemosensitivity. Pledgets with 4.7 mM kainic acid were placed bilaterally on the rostral, intermediate, or caudal ventilatory chemosensitive areas for 1-2 min in chloralose-urethan-anesthetized, paralyzed, vagotomized, glomectomized, and servo-ventilated cats. Application of kainic acid on the caudal or intermediate areas produced no consistent significant effects on eucapnic phrenic output or on the slope or maximum value of the phrenic nerve response to increased end-tidal PCO2. Rostral area kainic acid produced immediate augmentation and then diminution of blood pressure and phrenic output. Apnea developed in six of nine cats by 40 min. In all five cats in which it could be tested, the slope of the CO2 response was clearly decreased. Of [3H]kainic acid applied to the rostral area, 88.4% was shown to be within 2 mm of the ventral surface. Comparison of surface application sites of this and other studies suggests that an area overlapping the border of the original rostral and intermediate areas allows access to neurons involved in the chemoreception process, which may also provide tonic facilitatory input to cardiorespiratory systems.

Analysis of Firing Correlations Between Sympathetic Premotor Neuron Pairs in Anesthetized Cats

2001 ◽  
Vol 85 (4) ◽  
pp. 1697-1708 ◽  
Author(s):  
R. M. McAllen ◽  
D. Trevaks ◽  
A. M. Allen
Keyword(s):  
Cross Correlation ◽  
Ventrolateral Medulla ◽  
Electrode Recording ◽  
Synaptic Interactions ◽  
Premotor Neurons ◽  
Intermediate Time ◽  
Minor Part ◽  
Sympathetic Premotor Neurons ◽  
Neuronal Oscillators ◽  
A Minor

The activity of sympathetic premotor neurons in the rostral ventrolateral medulla (subretrofacial nucleus) supports sympathetic vasomotor tone, but the factors that drive these premotor neurons' activity have not been determined. This study examines whether either direct interconnections between subretrofacial neurons or synchronizing common inputs to them are important for generating their tonic activity. Simultaneous extracellular single-unit recordings were made from 32 pairs of sympathetic premotor neurons in the subretrofacial nucleus of chloralose-anesthetized cats. Paired spike trains were either separated by spike shape from a single-electrode recording (14 pairs) or recorded from two electrodes less than 250 μm apart (18 pairs). All neurons were inhibited by carotid baroreceptor stimulation and most had a spinal axon proven by antidromic stimulation from the spinal cord. Autocorrelation, inter-spike interval, and cardiac cycle-triggered histograms were constructed from the spontaneous activity of each neuron, and cross-correlation histograms covering several time scales were generated for each neuron pair. No significant peaks or troughs were found in short-term cross-correlation histograms (2 ms bins, ±100 ms range), providing no support for important local synaptic interactions. On an intermediate time scale (20 ms bins, ±1 s range), cross-correlation revealed two patterns indicating shared, synchronizing inputs. Repeating peaks and troughs (19/32 pairs) were due to the two neurons' common cardiac rhythmicity, of presumed baroreceptor origin. Single, zero time-spanning peaks of 40–180 ms width were seen in 5/32 cases. Calculations based on the prevalence and strength of these synchronizing inputs indicate that most of the ensemble spike activity of the subretrofacial neuron population is derived from asynchronous sources (be they intrinsic or extrinsic). If synchronizing sources such as neuronal oscillators were responsible for more than a minor part of the drive, they would be multiple, dispersed, and weak.

The 10-Hz sympathetic rhythm is dependent on raphe and rostral ventrolateral medullary neurons

1993 ◽  
Vol 264 (5) ◽  
pp. R857-R866 ◽  
Author(s):  
S. Zhong ◽  
Z. S. Huang ◽  
G. L. Gebber ◽  
S. M. Barman
Keyword(s):  
Sympathetic Nerves ◽  
The Body ◽  
Ventrolateral Medulla ◽  
Chemical Inactivation ◽  
Spinal Lesions ◽  
Medullary Raphe ◽  
Left And Right ◽  
Decerebrate Cats ◽  
Inferior Cardiac Nerve ◽  
Nerve Discharge

We studied the effects of brain stem and spinal lesions on the 10-Hz rhythms in left and right inferior cardiac sympathetic nerve discharge (SND) of baroreceptor-denervated, decerebrate cats. Unilateral medullary lesions [parasagittal section 1.5 mm lateral to midline, radiofrequency lesion of the rostral ventrolateral medulla (RVLM), or chemical inactivation (muscimol) of the RVLM] dramatically reduced the 10-Hz rhythmic discharges in the two nerves. Power in the 10-Hz band of ipsilateral inferior cardiac SND was reduced more than that in contralateral SND. In contrast, bilateral parasagittal medullary sections or microinjection of muscimol into the medullary raphe uniformly reduced the 10-Hz rhythmic discharges of both nerves. Unlike unilateral medullary lesions, rostral pontine or cervical spinal hemisection reduced the 10-Hz discharges of only the ipsilateral inferior cardiac nerve. The chemical inactivation experiments demonstrate that the 10-Hz rhythm in SND is dependent on medullary raphe and RVLM neurons. Moreover the experiments with unilateral lesions demonstrate a mutually facilitatory interaction of medullary circuits that are responsible for the 10-Hz rhythmic discharges in sympathetic nerves located on opposite sides of the body.

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