Recovery of phrenic activity and ventilation after cervical spinal hemisection in rats

2006 ◽  
Vol 100 (3) ◽  
pp. 800-806 ◽  
Author(s):  
David D. Fuller ◽  
Francis J. Golder ◽  
E. B. Olson ◽  
Gordon S. Mitchell
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Minute Ventilation ◽  
Nerve Activity ◽  
Time Points ◽  
Phrenic Motoneurons ◽  
Ventrolateral Funiculus ◽  
Barometric Plethysmography ◽  
Stimulation Of ◽  
Spinal Hemisection

We tested two hypotheses: 1) that the spontaneous enhancement of phrenic motor output below a C2 spinal hemisection (C2HS) is associated with plasticity in ventrolateral spinal inputs to phrenic motoneurons; and 2) that phrenic motor recovery in anesthetized rats after C2HS correlates with increased capacity to generate inspiratory volume during hypercapnia in unanesthetized rats. At 2 and 4 wk post-C2HS, ipsilateral phrenic nerve activity was recorded in anesthetized, paralyzed, vagotomized, and ventilated rats. Electrical stimulation of the ventrolateral funiculus contralateral to C2HS was used to activate crossed spinal synaptic pathway phrenic motoneurons. Inspiratory phrenic burst amplitudes ipsilateral to C2HS were larger in the 4- vs. 2-wk groups ( P < 0.05); however, no differences in spinally evoked compound phrenic action potentials could be detected. In unanesthetized rats, inspiratory volume and frequency were quantified using barometric plethysmography at inspired CO2 fractions between 0.0 and 0.07 (inspired O2 fraction 0.21, balance N2) before and 2, 3, and 5 wk post-C2HS. Inspiratory volume was diminished, and frequency enhanced, at 0.0 inspired CO2 fraction ( P < 0.05) 2-wk post-C2HS; further changes were not observed in the 3- and 5-wk groups. Inspiratory frequency during hypercapnia was unaffected by C2HS. Hypercapnic inspiratory volumes were similarly attenuated at all time points post-C2HS ( P < 0.05), thereby decreasing hypercapnic minute ventilation ( P < 0.05). Thus increases in ipsilateral phrenic activity during 4 wk post-C2HS have little impact on the capacity to generate inspiratory volume in unanesthetized rats. Enhanced crossed phrenic activity post-C2HS may reflect plasticity associated with spinal axons not activated by our ventrolateral spinal stimulation.

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat

1988 ◽  
Vol 118 (3) ◽  
pp. 471-483 ◽  
Author(s):  
L. M. Voloschin ◽  
E. Décima ◽  
J. H. Tramezzani
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Silent Period ◽  
High Amplitude ◽  
Milk Ejection ◽  
Nerve Activity ◽  
Thoracic Nerve ◽  
Myelinated Fibres ◽  
Stimulation Of

ABSTRACT Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 ± 63 and 868 ± 141 (s.e.m.) nerve fibres in the TBTN (85% non-myelinated) in virgin and lactating rats respectively. Non-myelinated fibres were enlarged in lactating rats; the modal value being 0·3–0·4 μm2 for virgin and 0·4–0·5 μm2 for lactating rats (P > 0·001; Kolmogorov–Smirnov test). The modal value for myelinated fibres was 3–6 μm2 in both groups. The compound action potential of the TBTN in response to electrical stimulation showed two early volleys produced by the Aα- and Aδ-subgroups of myelinated fibres (conduction velocity rate of 60 and 14 m/s respectively), and a late third volley originated in non-myelinated fibres ('C') group; conduction velocity rate 1·4 m/s). Before milk ejection the suckling pups caused 'double bursts' of fibre activity in the Aδ fibres of the TBTN. Each 'double burst' consisted of low amplitude action potentials and comprised two multiple discharges (33–37 ms each) separated by a silent period of around 35 ms. The 'double bursts' occurred at a frequency of 3–4/s, were triggered by the stimulation of the nipple and were related to fast cheek movements visible only by watching the pups closely. In contrast, the Aα fibres of the TBTN showed brief bursts of high amplitude potentials before milk ejection. These were triggered by the stimulation of cutaneous receptors during gross slow sucking motions of the pup (jaw movements). Immediately before the triggering of milk ejection the mother was always asleep and a low nerve activity was recorded in the TBTN at this time. When reflex milk ejection occurred, the mother woke and a brisk increase in nerve activity was detected; this decreased when milk ejection was accomplished. In conscious rats the double-burst type of discharges in Aδ fibres was not observed, possibly because this activity cannot be detected by the recording methods currently employed in conscious animals. During milk ejection, action potentials of high amplitude were conveyed in the Aα fibres of the TBTN. During the treading time of the stretch reaction (SR), a brisk increase in activity occurred in larger fibres; during the stretching periods of the SR a burst-type discharge was again observed in slow-conducting afferents; when the pups changed nipple an abrupt increase in activity occurred in larger fibres. In summary, the non-myelinated fibres of the TBTN are increased in diameter during lactation, and the pattern of suckling-evoked nerve activity in myelinated fibres showed that (a) the double burst of Aδ fibres, produced by individual sucks before milk ejection, could be one of the conditions required for the triggering of the reflex, and (b) the nerve activity displayed during milk-ejection action may result, at least in part, from 'non-specific' stimulation of cutaneous receptors. J. Endocr. (1988) 118, 471–483

Respiratory responses to aortic and carotid chemoreceptor activation in the dog

1991 ◽  
Vol 70 (6) ◽  
pp. 2539-2550 ◽  
Author(s):  
F. A. Hopp ◽  
J. L. Seagard ◽  
J. Bajic ◽  
E. J. Zuperku
Keyword(s):  
Electrical Stimulation ◽  
Carotid Body ◽  
Carotid Sinus ◽  
Chemical Stimulation ◽  
Respiratory Drive ◽  
Carotid Sinus Nerve ◽  
Nerve Activity ◽  
Respiratory Reflexes ◽  
Respiratory Responses ◽  
Stimulation Of

Respiratory responses arising from both chemical stimulation of vascularly isolated aortic body (AB) and carotid body (CB) chemoreceptors and electrical stimulation of aortic nerve (AN) and carotid sinus nerve (CSN) afferents were compared in the anesthetized dog. Respiratory reflexes were measured as changes in inspiratory duration (TI), expiratory duration (TE), and peak averaged phrenic nerve activity (PPNG). Tonic AN and AB stimulations shortened TI and TE with no change in PPNG, while tonic CSN and CB stimulations shortened TE, increased PPNG, and transiently lengthened TI. Phasic AB and AN stimulations throughout inspiration shortened TI with no changes in PPNG or the following TE; however, similar phasic stimulations of the CB and CSN increased both TI and PPNG and decreased the following TE. Phasic AN stimulation during expiration decreased TE and the following TI with no change in PPNG. Similar stimulations of the CB and CSN decreased TE; however, the following TI and PPNG were increased. These findings differ from those found in the cat and suggest that aortic chemoreceptors affect mainly phase timing, while carotid chemoreceptors affect both timing and respiratory drive.

Comparison of gene expression of 2-mo denervated, 2-mo stimulated-denervated, and control rat skeletal muscles

2005 ◽  
Vol 22 (2) ◽  
pp. 227-243 ◽  
Author(s):  
Tatiana Y. Kostrominova ◽  
Douglas E. Dow ◽  
Robert G. Dennis ◽  
Richard A. Miller ◽  
John A. Faulkner
Keyword(s):  
Gene Expression ◽  
Electrical Stimulation ◽  
Mrna Expression ◽  
Action Potentials ◽  
Skeletal Muscles ◽  
Microarray Study ◽  
Number Of Genes ◽  
Denervated Muscles ◽  
And Control ◽  
Stimulation Of

Loss of innervation in skeletal muscles leads to degeneration, atrophy, and loss of force. These dramatic changes are reflected in modifications of the mRNA expression of a large number of genes. Our goal was to clarify the broad spectrum of molecular events associated with long-term denervation of skeletal muscles. A microarray study compared gene expression profiles of 2-mo denervated and control extensor digitorum longus (EDL) muscles from 6-mo-old rats. The study identified 121 genes with increased and 7 genes with decreased mRNA expression. The expression of 107 of these genes had not been identified previously as changed after denervation. Many of the genes identified were genes that are highly expressed in skeletal muscles during embryonic development, downregulated in adults, and upregulated after denervation of muscle fibers. Electrical stimulation of denervated muscles preserved muscle mass and maximal force at levels similar to those in the control muscles. To understand the processes underlying the effect of electrical stimulation on denervated skeletal muscles, mRNA and protein expression of a number of genes, identified by the microarray study, was compared. The hypothesis was that loss of nerve action potentials and muscle contractions after denervation play the major roles in upregulation of gene expression in skeletal muscles. With electrical stimulation of denervated muscles, the expression levels for these genes were significantly downregulated, consistent with the hypothesis that loss of action potentials and/or contractions contribute to the alterations in gene expression in denervated skeletal muscles.

Electrical Stimulation of the Rat Lumbar Spine Induces Reflex Action Potentials in the Nerves to the Lower Abdomen

Spine ◽  
2000 ◽  
Vol 25 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Yuzuru Takahashi ◽  
Jiro Hirayama ◽  
Yoshio Nakajima ◽  
Seiji Ohtori ◽  
Kazuhisa Takahashi
Keyword(s):  
Electrical Stimulation ◽  
Lumbar Spine ◽  
Action Potentials ◽  
Lower Abdomen ◽  
Reflex Action ◽  
Stimulation Of

Interaction of descending spinal sympathetic pathways and afferent nerves

1978 ◽  
Vol 234 (3) ◽  
pp. H223-H229
Author(s):  
S. M. Barman ◽  
R. D. Wurster
Keyword(s):  
Nerve Fibers ◽  
Nerve Activity ◽  
Afferent Nerves ◽  
Afferent Nerve Fibers ◽  
Somatosympathetic Reflex ◽  
Reflex Activation ◽  
Dorsolateral Funiculus ◽  
Ventrolateral Funiculus ◽  
Stimulation Of ◽  
Excitatory Pathway

With the use of computer-aided techniques, the interaction of descending spinal sympathetic pathways and afferent nerve fibers (cervical dorsal roots and tibial nerve) in regulation of thoracic (T2) preganglionic nerve activity was investigated in anesthetized, vagotomized, and paralyzed cats. High-frequency activation of a sympathoinhibitory pathway (ventrolateral funiculus) depressed the evoked discharges in the T2 preganglionic nerve elicited by stimulation of a sympathoexcitatory pathway (dorsolateral funiculus) and the spinal component of the somatosympathetic reflex. Submaximal evoked responses were also inhibited through baroreceptor reflex activation (blood pressure elevations up to 225 mmHg). Facilitation of the spinal component of the somatosympathetic reflex occurred during stimulation of the excitatory pathway. Carotid occlusion (baroreceptor inactivation) facilitated the submaximal evoked discharges from stimulation of the descending excitatory pathway. These data support the contention that sympathetic nerve activity can be modified by the integration of excitatory and inhibitory impulses at the spinal level.

Pontine-evoked inspiratory inhibitions after antagonism of NMDA, GABAA, or glycine receptor

1993 ◽  
Vol 74 (3) ◽  
pp. 1265-1273 ◽  
Author(s):  
L. Ling ◽  
D. R. Karius ◽  
D. F. Speck
Keyword(s):  
Electrical Stimulation ◽  
Glycine Receptor ◽  
Inhibitory Response ◽  
Glycine Receptors ◽  
Onset Latency ◽  
Nerve Activity ◽  
Systemic Injection ◽  
Mk 801 ◽  
Inspiratory Motor ◽  
Stimulation Of

Single-shock stimulation of the pontine respiratory group (PRG) produces a transient short-latency inhibition of inspiratory motor activity. Stimulus trains delivered to the PRG can elicit a premature termination of inspiration. This study examined the involvement of N-methyl-D-aspartate (NMDA), gamma-aminobutyrateA (GABAA), or glycine receptors in these inhibitory responses. Experiments were conducted in decerebrate, paralyzed, and ventilated cats. Control responses to PRG stimulation were obtained from recordings of the left phrenic nerve activity. After systemic injection of MK-801, bicuculline, or strychnine (antagonists to NMDA, GABAA, or glycine receptors, respectively), responses to stimulation were again recorded. Inspiratory termination elicited by the PRG stimulation persisted after antagonism of NMDA, GABAA, or glycine receptors. The onset latency and duration of the transient inhibition were not changed after administration of bicuculline, but MK-801 administration did significantly prolong the duration of the transient inhibition. Strychnine significantly prolonged both the onset latency and the duration. These data suggest that none of the three receptor types is required in the inspiratory termination response elicited by electrical stimulation of the PRG region and that NMDA, GABAA, or glycine receptor-mediated neurotransmission is not solely responsible for the transient inhibitory response. However, the prolonged onset and duration of the transient inhibition after strychnine administration suggest that glycine does normally participate in this response.

scholarly journals Anesthesia and Increased Hypercarbic Drive Impair the Coordination between Breathing and Swallowing

2014 ◽  
Vol 121 (6) ◽  
pp. 1175-1183 ◽  
Author(s):  
Olivia M. D’Angelo ◽  
Daniel Diaz-Gil ◽  
Danuza Nunn ◽  
Jeroen C. P. Simons ◽  
Chloe Gianatasio ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electrical Stimulation ◽  
Respiratory Tract ◽  
Motor Response ◽  
Minute Ventilation ◽  
Foreign Material ◽  
Randomized Controlled ◽  
Ventilatory Drive ◽  
End Tidal ◽  
Stimulation Of

Abstract Background: Coordination between breathing and swallowing helps prevent aspiration of foreign material into the respiratory tract. The authors examined the effects of anesthesia and hypercapnia on swallowing–breathing coordination. Methods: In a randomized controlled crossover study, general anesthesia with propofol or sevoflurane was titrated using an up-down method to identify the threshold for suppression of the motor response to electrical stimulation of the forearm. Additional measurements included bispectral index, genioglossus electromyogram, ventilation (pneumotachometer), and hypopharyngeal pressure. During wakefulness and at each level of anesthesia, carbon dioxide was added to increase the end-tidal pressure by 4 and 8 mmHg. A swallow was defined as increased genioglossus activity with deglutition apnea and an increase in hypopharyngeal pressure. Spontaneous swallows were categorized as physiological (during expiration or followed by expiration) or pathological (during inspiration or followed by an inspiration). Results: A total of 224 swallows were analyzed. Anesthesia increased the proportion of pathological swallows (25.9% vs. 4.9%) and decreased the number of swallows per hour (1.7 ± 3.3 vs. 28.0 ± 22.3) compared to wakefulness. During anesthesia, hypercapnia decreased hypopharyngeal pressure during inspiration (−14.1 ± 3.7 vs. −8.7 ± 2 mmHg) and increased minute ventilation, the proportion of pathological swallows (19.1% vs. 12.3%), and the number of swallows per hour (5.5 ± 17.0. vs. 1.3 ± 5.5). Conclusions: Anesthesia impaired the coordination between swallowing and respiration. Mild hypercapnia increased the frequency of swallowing during anesthesia and the likelihood of pathological swallowing. During anesthesia, the risk for aspiration may be further increased when ventilatory drive is stimulated.

scholarly journals Wing Hair Plates in Crickets: Physiological Characteristics and Connections with Stridulatory Motor Neurones

1983 ◽  
Vol 107 (1) ◽  
pp. 21-47 ◽  
Author(s):  
C.J.H. ELLIOTT
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Viscous Drag ◽  
Behavioural Study ◽  
Wing Hair ◽  
Motor Neurones ◽  
Association Area ◽  
The Mean ◽  
Wing Folding ◽  
Stimulation Of

(1) Hairs in the subcostal hair plates of the wings of crickets have a high angular stiffness (5.5μNm rad1) when bent about their base. The mean threshold required to elicit action potentials is 15°. Viscous drag from air movements will not deflect the hairs sufficiently to excite them; this will only occur when the hair is bent by the opposite wing. (2) The hair sensillae project to the ventral association area of the mesothoracic ganglion, but the endings of the stridulatory motor neurones are all in dorsal or lateral neuropiles of the thoracic ganglia. (3) Electrical stimulation of the hair plates evokes reliable EPSPs in opener (M99), closer (M90) and wing folding (M85) motor neurones, after latencies of 4–20 ms, depending on the neurone. Properties of the hairs and motor neurones suggest that these EPSPs in the wing folding muscle (M85) and closer (M90) could play an important role in the control of wing position seen in recent behavioural study.

Synaptic Inhibition of Cat Phrenic Motoneurons by Internal Intercostal Nerve Stimulation

1999 ◽  
Vol 82 (3) ◽  
pp. 1224-1232 ◽  
Author(s):  
Mark C. Bellingham
Keyword(s):  
Phrenic Nerve ◽  
Intercostal Nerve ◽  
Evoked Responses ◽  
Nerve Activity ◽  
Synaptic Inputs ◽  
Phrenic Nerve Activity ◽  
Reflex Pathways ◽  
Phrenic Motoneurons ◽  
Conditioning Stimuli ◽  
Stimulation Of

Intracellular recordings from 65 phrenic motoneurons (PMNs) in the C5 segment and recordings of C5 phrenic nerve activity were made in 27 pentobarbitone-anesthetized, paralyzed, and artificially ventilated adult cats. Inhibition of phrenic nerve activity and PMN membrane potential hyperpolarization (48/55 PMNs tested) was seen after stimulation of the internal intercostal nerve (IIN) at a mean latency to onset of 10.3 ± 2.7 ms. Reversal of IIN-evoked hyperpolarization ( n = 14) by injection of negative current or diffusion of chloride ions occurred in six cases, and the hyperpolarization was reduced in seven others. Stimulation of the IIN thus activates chloride-dependent inhibitory synaptic inputs to most PMNs. The inhibitory phrenic nerve response to IIN stimulation was reduced by ipsilateral transection of the lateral white matter at the C3 level and was converted to an excitatory response by complete ipsilateral cord hemisection at the same level. After complete ipsilateral hemisection of the spinal cord at C3 level, stimulation of the IIN evoked both excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) in PMNs ( n = 10). It was concluded that IIN stimulation can evoke both excitatory and inhibitory responses in PMNs using purely spinal circuitry, but that excitatory responses are normally suppressed by a descending pathway in intact animals. Fifteen PMNs were tested for possible presynaptic convergence of inputs in these reflex pathways, using test and conditioning stimuli. Significant enhancement (>20%) of IPSPs were seen in seven of eight IIN-evoked responses using pericruciate sensorimotor cortex (SMC) conditioning stimuli, but only one of five IIN-evoked responses were enhanced by superior laryngeal nerve (SLN) conditioning stimuli. The IIN-evoked IPSP was enhanced in one of two motoneurons by stimulation of the contralateral phrenic nerve. It was concluded that presynaptic interneurons were shared by the IIN and SMC pathways, but uncommonly by other pathways. These results indicate that PMNs receive inhibitory synaptic inputs from ascending thoracocervical pathways and from spinal interneurons. These inhibitory reflex pathways activated by afferent inputs from the chest wall may play a significant role in the control of PMN discharge, in parallel with disfacilitation following reduced activity in bulbospinal neurons projecting to PMNs.

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