Cyanide excites medullary sympathoexcitatory neurons in rats

Sun, Miao‐Kun; Jeske, I; Dj, Reis

doi:10.1152/ajpregu.1992.262.2.r182

Cited by 44 publications

(56 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There is at least one plausible explanation that may account for the mechanism of NaCN-induced hyperventilation in 6-OHDAtreated larvae. NaCN is a metabolic poison and acts on chemoreceptors as a potent respiratory stimulant in both mammals and teleosts (González et al, 1992;Sun et al, 1992;. However, because there is no direct evidence for central O 2 or CO 2 chemoreceptors in water-breathing fish (Milsom, 2010a;Milsom, 2010b), the action of NaCN on central chemoreceptors is unlikely.…”

Section: Larvae From the Head (A-c) And Tail (De) (A-c)mentioning

confidence: 99%

Serotonergic neuroepithelial cells of the skin in developing zebrafish: morphology, innervation and oxygen-sensitive properties

Coccimiglio

Jonz

2012

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYIn teleost fish, O 2 chemoreceptors of the gills (neuroepithelial cells or NECs) initiate cardiorespiratory reflexes during hypoxia. In developing zebrafish, hyperventilatory and behavioural responses to hypoxia are observed before development of gill NECs, indicating that extrabranchial chemoreceptors mediate these responses in embryos. We have characterised a population of cells of the skin in developing zebrafish that resemble O 2 -chemoreceptive gill NECs. Skin NECs were identified by serotonin immunolabelling and were distributed over the entire skin surface. These cells contained synaptic vesicles and were associated with nerve fibres. Skin NECs were first evident in embryos 24-26hpost-fertilisation (h.p.f.), and embryos developed a behavioural response to hypoxia between 24 and 48h.p.f. The total number of NECs declined with age from approximately 300cells per larva at 3days post-fertilisation (d.p.f.) to ~120cells at 7d.p.f., and were rarely observed in adults. Acclimation to hypoxia (30mmHg) or hyperoxia (300mmHg) resulted in delayed or accelerated development, respectively, of peak resting ventilatory frequency and produced changes in the ventilatory response to hypoxia. In hypoxia-acclimated larvae, the temporal pattern of skin NECs was altered such that the number of cells did not decrease with age. By contrast, hyperoxia produced a more rapid decline in NEC number. The neurotoxin 6-hydroxydopamine degraded catecholaminergic nerve terminals that made contact with skin NECs and eliminated the hyperventilatory response to hypoxia. These results indicate that skin NECs are sensitive to changes in O 2 and suggest that they may play a role in initiating responses to hypoxia in developing zebrafish.

show abstract

Section: Larvae From the Head (A-c) And Tail (De) (A-c)mentioning

confidence: 99%

Serotonergic neuroepithelial cells of the skin in developing zebrafish: morphology, innervation and oxygen-sensitive properties

Coccimiglio

Jonz

2012

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…A bipolar concentric stimulating electrode (NE 100, David Kopf Inst. ; tip separation, 0 5 mm) was placed in the fascia surrounding the mandibular branch of the facial nerve in order to locate the motor nucleus of the facial nerve by recording antidromic field potentials (Sun & Guyenet, 1985;Sun, Jeske & Reis, 1992). The evoked field potentials were used as a landmark to locate sites for recording RVL-spinal vasomotor neurones and for placement of pipettes into the RVL for microinjections.…”

mentioning

confidence: 99%

NMDA receptor‐mediated sympathetic chemoreflex excitation of RVL‐spinal vasomotor neurones in rats.

Sun

Reis

1995

The Journal of Physiology

View full text Add to dashboard Cite

1. We investigated the role of N-methyl-D-aspartic acid (NMDA) receptors in mediating hypoxic excitation of the reticulospinal vasomotor neurones of the rostroventrolateral reticular nucleus (RVL) of the medulla oblongata in paralysed ventilated rats. 2. Unilateral close arterial injection of sodium cyanide (100 nmol) into the carotid sinus region or ventilation with 100% N2 for 12 s rapidly, reversibly and reproducibly excited the RVL-spinal vasomotor neurones, followed about 1-2 s later by increases in sympathetic nerve activity and arterial pressure, effects abolished by denervation of the ipsilateral carotid sinus nerve. 3. Ionophoresis onto the RVL-spinal vasomotor neurones of kynurenate (a wide-spectrum antagonist of the excitatory amino acid receptors) or of 2-amino-5-monophosphovaleric acid (APV; a selective NMDA receptor antagonist), but not of xanthurenate (an inactive analogue of kynurenate), blocked the excitation elicited by intracarotid cyanide or 12 s of hypoxia. Kynurenate completely and APV partially blocked the excitatory responses to ionophoretically applied L-glutamate. APV, however, did not alter the excitatory responses of the vasomotor neurones to ionophoreses of kainate and quisqualate. 4. Bilateral microinjection of kynurenate (10 nmol, 50 nl per site) or APV (5 nmol, 50 nl per site) into the RVL blocked the increases in arterial pressure elicited by intracarotid cyanide or 12 s of 100 % N2 ventilation. 5. Twenty seconds of intratracheal administration of 100 % N2 resulted in complex and prolonged elevations of arterial pressure, the late component of which was affected neither by sinus denervation nor by microinjections of kynurenate or APV into the RVL. 6. We conclude that the sympathetic and cardiovascular responses to stimulation of arterial chemoreceptors result from excitation of RVL-spinal vasomotor neurones via activation of the NMDA subtypes of the excitatory amino acid receptors of the neurones. In contrast, the failure of these antagonists to influence the delayed excitation of the RVL-spinal vasomotor neurons by more prolonged exposure to N2 inhalation further supports the view that these neurones are directly stimulated by hypoxia.In mammals, hypoxia elicits a differentiated activation of the sympathetic nervous system

show abstract

“…Producing local hypoxia with NaCN discretely within C1, an essential site for tonic generation of vasomotor tone and the reflex regulation of blood pressure (50), directly excites C1 neurons (54,55) and increases sympathetic nerve discharge (41). The respiratory region located just rostral to the C1 region, the preBötC, is also directly excited by local hypoxia with NaCN causing augmented respiratory bursts, i.e., gasps/sighs (53) and may be important for autoresuscitation (20).…”

Section: Discussionmentioning

confidence: 99%

“…cellular pathways in common with hypoxic hypoxia by binding to heme groups in competition with O 2 , including cytochrome aa3 and HO. Thus, exposure to NaCN in cells is akin to O 2 depletion and has been a widely used model of hypoxia (27,54,55,58). Comparisons of the responses to NaCN and hypoxic hypoxia have been made previously in C1 neurons and carotid body type 1 cells, and both forms of hypoxia produced similar membrane potential responses and activation of specific ionic conductances, suggesting the same mechanism of hypoxic excitation (27, 54 -56, 64).…”

Section: Advantages and Limitations Of The In Vitro Modelmentioning

confidence: 99%

“…However, studies done in vivo (53,54) and in vitro (38,55,59) have demonstrated unique sites within the rostral ventrolateral medulla (RVLM) that increase their activity in response to local hypoxia. For example, in vivo, local hypoxia within the C1 region (54) and pre-Bötzinger complex (preBötC) (53) produce increases in sympathetic and respiratory nerve activity, respectively. Using in vitro preparations, neurons in the RVLM have been shown to be excited by hypoxia in both medullary slices (55) and primary cell cultures (38).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Heme oxygenase is necessary for the excitatory response of cultured neonatal rat rostral ventrolateral medulla neurons to hypoxia

D’Agostino

Mazza²,

Neubauer³

2009

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Heme oxygenase has been linked to the oxygen-sensing function of the carotid body, pulmonary vasculature, cerebral vasculature, and airway smooth muscle. We have shown previously that the cardiorespiratory regions of the rostral ventrolateral medulla are excited by local hypoxia and that heme oxygenase-2 (HO-2) is expressed in the hypoxia-chemosensitive regions of the rostral ventrolateral medulla (RVLM), the respiratory pre-Bötzinger complex, and C1 sympathoexcitatory region. To determine whether heme oxygenase is necessary for the hypoxic-excitation of dissociated RVLM neurons (P1) cultured on confluent medullary astrocytes (P5), we examined their electrophysiological responses to hypoxia (NaCN and low Po(2)) using the whole-cell perforated patch clamp technique before and after blocking heme oxygenase with tin protoporphyrin-IX (SnPP-IX). Following the electrophysiological recording, immunocytochemistry was performed on the recorded neuron to correlate the electrophysiological response to hypoxia with the expression of HO-2. We found that the responses to NaCN and hypoxia were similar. RVLM neurons responded to NaCN and low Po(2) with either depolarization or hyperpolarization and SnPP-IX blocked the depolarization response of hypoxia-excited neurons to both NaCN and low Po(2) but had no effect on the hyperpolarization response of hypoxia-depressed neurons. Consistent with this observation, HO-2 expression was present only in the hypoxia-excited neurons. We conclude that RVLM neurons are excited by hypoxia via a heme oxygenase-dependent mechanism.

show abstract

Cyanide excites medullary sympathoexcitatory neurons in rats

Cited by 44 publications

References 0 publications

Serotonergic neuroepithelial cells of the skin in developing zebrafish: morphology, innervation and oxygen-sensitive properties

Serotonergic neuroepithelial cells of the skin in developing zebrafish: morphology, innervation and oxygen-sensitive properties

NMDA receptor‐mediated sympathetic chemoreflex excitation of RVL‐spinal vasomotor neurones in rats.

Heme oxygenase is necessary for the excitatory response of cultured neonatal rat rostral ventrolateral medulla neurons to hypoxia

Contact Info

Product

Resources

About