The respiratory pattern generator modulates the sympathetic outflow, strength of which is enhanced by challenges produced hypoxia. This coupling due to respiratory-modulated presympathetic neurons in rostral ventrolateral medulla (RVLM), but underlining electrophysiological mechanisms remain unclear. For a better understanding neural substrates responsible for generation this respiratory-sympathetic coupling, we combined immunofluorescence, single cell qRT-pCR, and recordings RVLM situ...

The main O 2 arterial chemoreceptors are the carotid bodies (CBs), which mediate hyperventilation in response to short-term sustained hypoxia (SH). CBs contain glomus cells expressing K + channels, inhibited by hypoxia, leading neurotransmitters release. ATP released and type II has been considered essential for chemosensory processing under physiological pathophysiological conditions. Although systemic effects of chronic activation SH well known, early (first 24 hours) cellular molecular...

At rest, inspiration is an active process while expiration passive. However, high chemical drive (hypercapnia or hypoxia) activates central and peripheral chemoreceptors triggering reflex increases in expiration. The Locus Coeruleus contains noradrenergic neurons (A6 neurons) that increase their firing frequency when exposed to hypercapnia hypoxia. Using recently developed neuronal hyperpolarising technology conscious rats, we tested the hypothesis A6 are a part of vigilance centre for...

The carotid bodies (CBs) of spontaneously hypertensive (SH) rats exhibit hypertonicity and hyperreflexia contributing to heightened peripheral sympathetic outflow. We hypothesized that CB hyperexcitability is driven by its own innervation.To test this, the chemoreflex was activated (NaCN 50-100 µL, 0.4 µg/µL) in SH Wistar situ before after: (i) electrical stimulation (ES; 30 Hz, 2 ms, 10 V) superior cervical ganglion (SCG), which innervates CB; (ii) unilateral resection SCG (SCGx); (iii)...

Abstract Active expiration is essential for increasing pulmonary ventilation during high chemical drive (hypercapnia). The lateral parafacial (pF L ) region, which contains expiratory neurones, drives abdominal muscles active in response to hypercapnia. However, the electrophysiological properties and synaptic mechanisms determining activity of pF as well specific conditions their emergence, are not fully understood. Using whole cell electrophysiology single quantitative RT‐PCR techniques,...

Rats subjected to sustained hypoxia (SH) present increases in arterial pressure (AP) and glutamatergic transmission the nucleus tractus solitarius (NTS) neurons sending projections ventrolateral medulla (VLM). Treatment with minocycline, a microglial inhibitor, attenuated increase AP response SH. The amplitude of postsynaptic currents NTS-VLM neurons, induced by mechanisms, was blunted minocycline treatment. number cells increased NTS vehicle-treated SH rats but not minocycline-treated rats....

The control of the excitability in magnocellular neurosecretory cells (MNCs) supraoptic nucleus has been attributed mainly to synaptic inputs from circunventricular organs. However, nitric oxide (NO), a gaseous messenger produced this during isotonic and short-term hypertonic conditions, is an example modulator that can act directly on MNCs modulate their firing rate. NO inhibits electrical MNCs, leading decrease release vasopressin oxytocin. Although effects are well established, mechanism...

Sympathetic activity displays rhythmic oscillations generated by brainstem inspiratory and expiratory neurons. Amplification of these respiratory-related is observed in rats under enhanced central respiratory drive or during development neurogenic hypertension. Herein, we evaluated the involvement ventral medullary sympatho-excitatory catecholaminergic C1 neurons, using inhibitory Drosophila allatostatin receptors, for expiratory-related sympathetic submitted to chronic intermittent hypoxia...

The phenotypic differentiation between oxytocin (OT)- and vasopressin (VP)-secreting magnocellular neurosecretory cells (MNCs) from the supraoptic nucleus is relevant to understanding how several physiological pharmacological challenges affect their electrical activity. Although firing patterns of OT VP neurons, both in vivo vitro, may appear different each other, much assumed about characteristics. These assumptions make it practically impossible obtain a confident based exclusively on...

The carotid bodies are peripheral chemoreceptors and contribute to the homeostatic maintenance of arterial levels O2, CO2, [H+]. They have attracted much clinical interest recently because realization that aberrant signaling in these organs is associated with several pathologies including hypertension. Herein, we describe data suggesting sympathetic overactivity neurogenic hypertension is, at least part, dependent on body tonicity hyperreflexia related changes electrophysiological properties...

Chronic intermittent hypoxia (CIH) produces respiratory-related sympathetic overactivity and hypertension in rats. In this study, we tested the hypothesis that enhanced central respiratory modulation of activity after CIH also decreases sympathoinhibitory component baroreflex rats, which may contribute to development hypertension. Wistar rats were exposed or normoxia (control group) for 10 days. Phrenic nerve, thoracic neurons rostral ventrolateral medulla caudal recorded situ preparations...

Key points Acute hypoxia induces active expiration in rectus abdominis (RA) muscles conscious freely moving rats, although its overall contribution is smaller than internal oblique (IO) muscles. Tonically and silent RA motoneurons were identified vitro preparations of rat spinal cords. Sustained (SH) increased the synaptic strength induced morphological changes tonically motoneurons. Expiratory recorded situ preparation SH enhanced both excitability transmission those firing during stage 2...

New Findings What is the central question of this study? Does parafacial respiratory group (pFRG), which mediates active expiration, recruit nasofacial and oral motoneurons to coordinate motor activities that engage muscles controlling airways in rats during expiration. main finding its importance? Hypercapnia/acidosis or pFRG activation evoked expiration stimulated nerves responsible for control patency simultaneously. Bilateral inhibition abolished simultaneous induced by...

Dysfunctions in the hypoglossal control of tongue extrinsic muscles are implicated obstructive sleep apnoea (OSA) syndrome. Chronic intermittent hypoxia (CIH), an important feature OSA syndrome, produces deleterious effects on motor oropharyngeal resistance, but whether motoneurones innervating affected by CIH is unknown. We show that enhanced respiratory-related activity rat nerve protrudor and retractor muscles. Intracellular recordings revealed increases firing frequency synaptic...

What is the central question of this study? Adrenomedullin in rostral ventrolateral medulla (RVLM) increases sympathetic activity; given that adrenomedullin released during hypoxia, what are effects its agonism and antagonism RVLM after chronic intermitent hypoxia (CIH) exposure? main finding importance? CIH exposure sensitizes adrenomedullin-dependent mechanisms RVLM, supporting role as a sympathoexcitatory neuromodulator. A novel mechanism was identified for generation overdrive...

Key points Carotid body (CB) chemoreceptors are hyperactive in hypertension, and their acute activation produces bronchoconstriction. We show that the respiratory‐modulated bronchiolar tone, pulmonary parasympathetic efferent activity, firing frequency synaptic excitation of bronchoconstrictor motoneurones nucleus ambiguus were all enhanced spontaneous hypertensive (SH) rats. In SH rats, CB denervation reduced respiratory‐related parasympathetic‐mediated tone to levels seen normotensive...

Abstract Aims Stimulation of peripheral chemoreceptors, as during hypoxia, increases breathing and respiratory‐related sympathetic bursting. Activation catecholaminergic C1 neurones induces sympathoexcitation, while its ablation reduces the chemoreflex sympathoexcitatory response. However, no study has determined respiratory phase(s) in which pre‐sympathetic are recruited by chemoreceptor whether neurone activation affects all phases modulation activity. We addressed these unknowns testing...