Intramedullary sodium cyanide injection on respiratory and vasomotor responses in cats

Mitra, J.; Dev, Nagendu B.; Trivedi, Roopa; Amini, Saeid B.; Ernsberger, Paul; Cherniack, Neil S.

doi:10.1016/0034-5687(93)90069-m

Cited by 30 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Again, our data showing that DAMGO microinjections into the regions 1.0 mm outside the cMRR or the mMRR had no remarkable effect on V̇e support the conclusion that the spread was considerably limited. Consistent with our study, several investigators have previously calculated that microinjection of a volume of 100 nl into the brainstem could spread as far as 1.0 mm (Lipski et al , 1988; Mitra et al , 1993). However, we still cannot rule out the possible involvement of the vicinity of the MRR in the DAMGO-induced depression of the HVR.…”

Section: Discussionsupporting

confidence: 92%

“…According to the rat stereotaxic atlas of Paxinos and Watson (1998), each of the three subnuclei (RMg, RPa, ROb) covers a relatively large area (approximately 0.7– 1.0 mm 3 ), centered at the middle. A volume of 100 nl was used because previous studies have calculated that microinjecting this volume into the brainstem could spread as far as ~1 mm 3 (Lipski et al , 1988; Mitra et al , 1993). In fact, microinjecting this volume (100 nl) into the raphe (Nucci et al , 2008) and hypothalamus (Deolindo et al , 2008) of rats has been used by other investigators recently.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Opioid μ-receptors in medullary raphe region affect the hypoxic ventilation in anesthetized rats

Zhang

et al. 2009

Respiratory Physiology & Neurobiology

View full text Add to dashboard Cite

Opioids can attenuate the peripheral chemoreceptor-mediated hypoxic ventilatory response (HVR) by acting on central μ-type opioid receptors. Since the medullary raphe region (MRRs) expresses abundant μ-receptors and participates in modulating HVR, we tested the role of μ-receptors within the caudal, medial, and rostral MRR (cMRR, mMRR, and rMRR) in modulating the HVR. We recorded cardiorespiratory activities and their responses to isocapnic hypoxia in anesthetized rats before and after local microinjection of DAMGO into the MRR, and intravenous administration of DAMGO (100 μg/kg) alone or coupled with a previous local injection of CTAP. Microinjecting DAMGO into the cMRR or mMRR but not the rMRR significantly attenuated the HVR. However, systemic DAMGO-induced HVR attenuation was not significantly affected by pretreating the cMRR and mMRR with CTAP. Our data suggest that cMRR and mMRR μ-receptors are capable of depressing the HVR, while their contribution to the attenuated HVR by systemic DAMGO is limited.

show abstract

Section: Discussionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Opioid μ-receptors in medullary raphe region affect the hypoxic ventilation in anesthetized rats

Zhang

et al. 2009

Respiratory Physiology & Neurobiology

View full text Add to dashboard Cite

show abstract

“…Accordingly, theoretical calculations by Nicholson (32) demonstrate that, based on a 10-nl injection into the brain tissue, the concentration of the injectate 300 m from the injection site never exceeds 20% of the initial dose. Additionally, Lipski et al (29) estimated that in a 30-nl microinjection, the drug diffused ϳ325 m, whereas Mitra et al (30) reported that microinjections performed in a volume of 100 nl could spread as far as 1 mm. On the basis of these notions, in our experiments we used threshold doses, i.e., doses that elicited a thermoregulatory action when microinjected intra-AVPO, but not when administered peri-AVPO (Figs.…”

Section: Methodological Considerationsmentioning

confidence: 98%

Antipyretic role of the NO-cGMP pathway in the anteroventral preoptic region of the rat brain

Steiner

Antunes‐Rodrigues

McCann

et al. 2002

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

We tested the hypothesis that nitric oxide (NO) acts in the anteroventral preoptic region (AVPO) modulating fever. To this end, body core temperature (T(c)) of rats was monitored by biotelemetry before and after pharmacological modulation of the NO pathway. Nitrite/nitrate and cGMP in the anteroventral third ventricular region (AV3V), where the AVPO is located, were also determined. Intra-AVPO microinjection of the NO synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 12.5 microg) did not affect basal T(c), but it enhanced the early stage of lipopolysaccharide (LPS) fever, indicating that NO plays an antipyretic role in the AVPO. In agreement, intra-AVPO microinjection of the NO donor sodium nitroprusside (5 microg) reduced T(c). The antipyretic effect of NO seems to be mediated by cGMP because 1) NO has been shown to activate soluble guanylate cyclase, 2) intra-AVPO microinjection of 8-bromo-cGMP (8-BrcGMP) reduced T(c), and 3) the changes in AV3V levels of nitrite/nitrate and cGMP were similar in the course of fever. Additionally, we observed that nitrite/nitrate and cGMP levels decreased in the AV3V after, but not before, the onset of LPS fever, showing that the activity of the NO-cGMP pathway is reduced in the AV3V after intraperitoneal LPS, a mechanism that could contribute to the genesis and maintenance of fever. It was also observed that the efficacy of 8-BrcGMP in reducing T(c) in the AVPO is increased after LPS, emphasizing that the NO-cGMP pathway is antipyretic. This response could explain why intra-AVPO L-NMMA enhanced the early stage of LPS fever, even though the activity of the NO pathway before the onset of fever was unchanged. In summary, these data support an antipyretic role of the NO-cGMP pathway in the AVPO.

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%

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

Intramedullary sodium cyanide injection on respiratory and vasomotor responses in cats

Cited by 30 publications

References 19 publications

Opioid μ-receptors in medullary raphe region affect the hypoxic ventilation in anesthetized rats

Opioid μ-receptors in medullary raphe region affect the hypoxic ventilation in anesthetized rats

Antipyretic role of the NO-cGMP pathway in the anteroventral preoptic region of the rat brain

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

Contact Info

Product

Resources

About