Edison-Pablo Reyes

University of Desarrollo, CiudadSantiago, Santiago, Chile

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Publications (6)13.93 Total impact

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    ABSTRACT: Lipopolysaccharide (LPS) administered I.P. increases significantly the activation of c-Fos in neurons of the nucleus of the solitary tract (NTS), which in turn activates hypothalamus-pituitary-adrenal axis. The vagus nerve appears to play a role in conveying cytokines signals to the central nervous system (CNS), since -in rodent models of sepsis- bilateral vagotomy abolishes increases in plasmatic glucocorticoid levels, but does not suppress c-Fos NTS activation. Considering that NTS also receives sensory inputs from carotid body chemoreceptors, we evaluated c-Fos activation and plasmatic cortisol levels 90 min after I.P. administration of 15 mg/kg LPS. Experiments were performed in male Sprague-Dawley rats, in control conditions and after bilateral carotid neurotomy (BCN). LPS administration significantly increases the number of c-Fos positive NTS neurons and plasmatic cortisol levels in animals with intact carotid/sinus nerves. When LPS was injected after BCN, the number of c-Fos positive NTS neurons, and plasmatic cortisol levels were not significantly modified. Our data suggest that carotid body chemoreceptors might mediate CNS activation during sepsis.
    Advances in experimental medicine and biology 01/2012; 758:185-90. · 1.83 Impact Factor
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    ABSTRACT: The study of the initial effects of a sudden and brief replacement of air by pure oxygen has been proposed as a tool (Dejours' test) to determine the tonic influence that arterial (peripheral) chemoreceptors were exerting upon ventilation under previous normoxic conditions. Therefore, the acute ventilatory response to transient hyperoxia should be used to assess the level of hypoxic chemosensory drive. In spontaneously ventilated pentobarbitone-anesthetized cats, we observed that the degree of ventilatory depression provoked by hyperoxia was correlated to the degree of previous hypoxia. Minimal tidal volumes (V(T)) or transient apnea were reached between second to fourth cycles after switching from 5% to 100% O(2) breathing. Continuous recordings of chemosensory discharges from one carotid (sinus) nerve allowed correlation of the falls in frequency of chemosensory discharges to the degree of hyperoxia-induced ventilatory depression and provided an accurate measure of the prevailing chemosensory drive of ventilation exerted during hypoxic steady-state conditions.
    Advances in experimental medicine and biology 01/2012; 758:137-42. · 1.83 Impact Factor
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    ABSTRACT: In the absence of information on functional manifestations of carotid body (CB) inflammation, we studied an experimental model in which lipopolysaccharide (LPS) administration to pentobarbitone-anaesthetized cats was performed by topical application upon the CB surface or by intravenous infusion (endotoxaemia). The latter caused: (i) disorganization of CB glomoids, increased connective tissue, and rapid recruitment of polymorphonuclear cells into the vascular bed and parenchyma within 4 h; (ii) increased respiratory frequency and diminished ventilatory chemoreflex responses to brief hypoxia (breathing 100% N(2) for 10 s) and diminished ventilatory chemosensory drive (assessed by 100% O(2) tests) during normoxia and hypoxia; (iii) tachycardia, increased haematocrit and systemic hypotension in response to LPS i.v.; and (iv) increased basal frequency of carotid chemosensory discharges during normoxia, but no change in maximal chemoreceptor responses to brief hypoxic exposures. Lipopolysaccharide-induced tachypnoea was prevented by prior bilateral carotid neurotomy. Apoptosis was not observed in CBs from cats subjected to endotoxaemia. Searching for pro-inflammatory mediators, tumour necrosis factor-alpha (TNF-alpha) was localized by immunohistochemistry in glomus and endothelial cells; reverse transcriptase-polymerase chain reaction revealed that the CB expresses the mRNAs for both type-1 (TNF-R1) and type-2 TNF-alpha receptors (TNF-R2); Western blot confirmed a band of the size expected for TNF-R1; and histochemistry showed the presence of TNF-R1 in glomus cells and of TNF-R2 in endothelial cells. Experiments in vitro showed that the frequency of carotid nerve discharges recorded from CBs perfused and superfused under normoxic conditions was not significantly modified by TNF-alpha, but that the enhanced frequency of chemosensory discharges recorded along responses to hypoxic stimulation was transiently diminished in a dose-dependent manner by TNF-alpha injections. The results suggest that the CB may operate as a sensor for immune signals, that the CB exhibits histological features of acute inflammation induced by LPS, that TNF-alpha may participate in LPS-induced changes in chemosensory activity and that some pathophysiological reactions to high levels of LPS in the bloodstream may originate from changes in CB function.
    Experimental Physiology 08/2008; 93(7):892-907. · 2.79 Impact Factor
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    ABSTRACT: ABSTRACT In the absence of information on functional manifestations of carotid body (CB) inflammation, we studied an experimental model in which lipopolysaccharide (LPS) administration to pentobarbitone anesthetized cats was performed by topical application upon CB surface or IV infusion (endotoxaemia). This caused: i) disorganization of CB glomoids, increased connective tissue, rapid recruitment of polymorphonuclear (PMN) cells into vascular bed and parenchyma within four hours; ii) increased respiratory frequency and diminished ventilatory chemoreflex responses to brief hypoxia (breathing 100% N2 for 10 s), ventilatory chemosensory drive (assessed by 100% O2 tests) during normoxia and hypoxia; iii) tachycardia, increased haematocrit and systemic hypotension in response to LPS I.V.; iv) increased basal frequency of carotid chemosensory discharges during normoxia, but no change in maximal chemoreceptor responses to brief hypoxic exposures. LPS-induced tachypnea was prevented by prior bilateral carotid neurotomy. Apoptosis was not observed in CBs from cats subjected to endotoxaemia. Searching for pro-inflammatory mediators, tumour necrosis factor-alpha (TNF-alpha) was localized by immunohistochemistry in glomus and endothelial cells, RT-PCR revealed that the CB expresses the mRNAs for both type-1 and -2 TNF-alpha receptors; Western-blot confirmed a band of the size expected for TNF-R1; and histochemistry showed the presence of TNF-R1 in glomus cells and of TNF-R2 in endothelial cells. Experiments in vitro showed that the frequency of carotid nerve discharges recorded from CBs perfused and superfused under normoxic conditions was not significantly modified by TNF-alpha, but that the enhanced frequency of chemosensory discharges recorded along responses to hypoxic stimulation was transiently and dose-dependently diminished by TNF-alpha injections. Results suggest that the CB may operate as a sensor for immune signals, that the CB exhibits histological features of acute inflammation induced by LPS, that TNF-alphamay participate in LPS-induced changes in chemosensory activity and that some pathophysiological reactions to high levels of LPS in the bloodstream may originate from changes in CB function.
    Experimental Physiology 03/2008; · 2.79 Impact Factor
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    Edison-Pablo Reyes, Julio Alcayaga, Patricio Zapata
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    ABSTRACT: We investigate possible interactions between acetylcholine (ACh)- and adenosine 5'-triphosphate (ATP)-induced responses of petrosal ganglion, where the perikarya of most sensory neurons of the glossopharyngeal nerve are located. Experiments were performed on petrosal ganglia excised from pentobarbitone-anesthetized cats, desheathed and perfused in vitro. Separate applications of ACh and ATP to the exposed surface of the ganglion induced bursts of antidromic potentials recorded from the carotid (sinus) nerve branch of the glossopharyngeal nerve, which frequencies were dependent on the dose of the applied agonists. The simultaneous application of previously determined ED50s of ACh and ATP provoked responses corresponding closely to the simple addition of the responses elicited by the separate application of each agent. Responses usually subsided within 1 min of stimuli application but were followed by periods of refractoriness to subsequent application of the same agent. After determining the timing for recovering from desensitization to the ED50s of ACh and ATP applied separately, ACh was applied while the preparation had been desensitized to ATP and then ATP was applied during desensitization to ACh, but responses obtained were similar to control responses induced by each agent separately. In summary, ACh- and ATP-induced responses of petrosal ganglion neurons are simply additive, followed by a few minute lasting desensitization, but cross-desensitization was not observed. Thus, ACh and ATP seem to operate through independent receptors, activating separate ionic channels, whose coincident currents do not interfere each other.
    Brain Research 09/2006; 1107(1):97-103. · 2.88 Impact Factor
  • Advances in experimental medicine and biology 02/2003; 536:277-83. · 1.83 Impact Factor

Publication Stats

24 Citations
13.93 Total Impact Points

Institutions

  • 2008
    • University of Desarrollo
      CiudadSantiago, Santiago, Chile
    • Universidad Andrés Bello
      CiudadSantiago, Santiago, Chile
  • 2003–2006
    • University of Santiago, Chile
      • • Facultad de Ciencia
      • • Facultad de Química y Biología
      Santiago, Region Metropolitana de Santiago, Chile