Browsing by Author "Xavier, Carlos Henrique"

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    Bezold-Jarisch reflex in sino-aortic denervated malnourished rats.
    (2011) Bezerra, Vanessa Moraes; Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Fontes, Marco Antônio Peliky; Cardoso, Leonardo Máximo; Fernandes, Luciano Gonçalves; Chianca Júnior, Deoclécio Alves
    In this study we assessed the role of Bezold–Jarisch reflex (BJR) in the regulation of blood pressure (BP) of malnourished (MN) and control rats (CN) with sino-aortic denervation (SAD). Fischer rats were fed diets containing either 6% (MN) or 15% (CN) protein for 35 days after weaning. These rats underwent sham or SAD and catheterization of femoral artery and vein for BP measurements and drug injection. Phenylbiguanide (PBG 5 μg/kg, i.v.) for activation BJR, produced bradycardia (− 317 ± 22 bpm for CN vs. − 372 ± 16 bpm for MN) and hypotension (− 57 ± 4 mm Hg for CN vs. − 54 ± 6 mm Hg for MN. After SAD, MN rats had reduced hypotensive (− 37 ± 7 mmHg for MN vs. − 82 ± 6 mm Hg for CN) and bradycardic (− 124 ± 17 for MN vs. − 414 ± 20 bpm CN) responses to BJR activation. To evaluate the contribution of the parasympathetic component due to BJR for the fall in BP, methyl atropine bromide, was given between two injections of PBG (5 μg/kg) separated by 10 min each other. Both bradycardic (− 216 ± 21 bpm before and − 4±3 bpm after for CN − 226±43 bpm before and − 9±20 bpm after for MN) and hypotensive (− 42±4 mm Hg before and − 6±1 mm Hg after for CN − 33±9 mm Hg before and − 5±2 mm Hg after for MN) responses were abolished in CN and MN groups. These data indicate that dietary protein malnutrition changes the relation between baroreflex and BJR required for maintenance of the BP during malnourishment.
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    Editorial: Stress-related diseases and dysfunctions.
    (2022) Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Chianca Júnior, Deoclécio Alves; Fontes, Marco Antônio Peliky; Crestani, Carlos César
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    Editorial: Stress-related diseases and Q2 dysfunctions.
    (2022) Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Chianca Júnior, Deoclécio Alves; Fontes, Marco Antônio Peliky; Crestani, Carlos César
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    Malnutrition alters the cardiovascular responses induced by central injection of tityustoxin in Fischer rats.
    (2013) Silva, Fernanda Cacilda dos Santos; Guidine, Patrícia Alves Maia; Ribeiro, Mara Fernandes; Fernandes, Luciano Gonçalves; Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Silva, Marcelo Eustáquio; Santos, Tasso Moraes; Moraes, Márcio Flávio Dutra; Chianca Júnior, Deoclécio Alves
    Scorpion envenoming and malnutrition are considered two important public health problems in Brazil, involving mainly children. Both these conditions are more common among the economically stratified lower income portion of the population, thus suggesting that these factors should be analyzed concomitantly. It is known that cardiorespiratory manifestations, as cardiac arrhythmias, arterial hypertension and hypotension, pulmonary edema and circulatory failure are the main “causa mortis” of scorpion envenomation. Additionally, there are evidences in the literature that deficiencies in dietary intake endanger the CNS and modify the cardiovascular homeostasis. Then, the objective of this work is to evaluate the protein malnourished effect on cardiovascular responses induced by tityustoxin (TsTX, an a-type toxin extracted from the Tityus serrulatus scorpion venom). Fischer rats (n ¼ 20) were injected i.c.v. with TsTX and divided in control and malnorished groups, which were, respectively, submitted to a control and a low-protein diet. Arterial pressure recordings were done until death of the animals. Although both groups presented an increased mean arterial pressure after TsTX injection, this increase was smaller and delayed in malnourished rats, when compared to control rats. In addition, heart rate increased only in rats from the control group. Finally, malnourished rats had an increase in survival time (9:9/13.5
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    Sympathoinhibition to Bezold Jarisch reflex is attenuated in protein malnourished rats.
    (2011) Bezerra, Vanessa Moraes; Xavier, Carlos Henrique; Fernandes, Luciano Gonçalves; Cardoso, Leonardo Máximo; Fontes, Marco Antônio Peliky; Chianca Júnior, Deoclécio Alves
    Malnutrition affects cardiovascular reflexes, including chemoreflex and baroreflex. In this study we assessed the hypothesis that malnourishment changes the responses in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) evoked from Bezold–Jarischreflex (BJR). Fischer rats were fed diets containing either (6% malnourished or 14% control) protein for 35 days after weaning. There were no differences in baseline MAP (102 ± 4 vs. 95 ± 3 mmHg) whereas higher baseline HR (478 ± 18 vs. 360 ± 11 bpm; P < 0.05,) and reduced sympathoinhibition (ΔRSNA = −54 ± 9 vs. −84 ± 7%; P = 0.0208) to BJR activation were found in malnourishedrats. We conclude that malnutrition affects the sympathetic control of BJR.
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    The role of dorsomedial hypotalamus ionotropic glutamate receptors in the hypertensive and tachycardic responses evoked by Tityustoxin intracerebroventricular injection.
    (2015) Silva, Fernanda Cacilda dos Santos; Guidine, Patrícia Alves Maia; Machado, Natália Lima Santos; Xavier, Carlos Henrique; Menezes, Rodrigo Cunha Alvim de; Santos, Tasso Moraes; Moraes, Márcio Flávio Dutra; Chianca Júnior, Deoclécio Alves
    The scorpion envenoming syndrome is an important worldwide public health problem due to its high incidence and potential severity of symptoms. Some studies address the high sensitivity of the central nervous system to this toxin action. It is known that cardiorespiratory manifestations involve the activation of the autonomic nervous system. However, the origin of this modulation remains unclear. Considering the important participation of the dorsomedial hypotalamus (DMH) in the cardiovascular responses during emergencial situations, the aim of this work is to investigate the involvement of the DMH on cardiovascular responses induced by intracerebroventricular (icv) injection of Tityustoxin (TsTX, a a-type toxin extracted from the Tityus serrulatus scorpion venom). Urethane-anaesthetized male Wistar rats (n = 30) were treated with PBS, muscimol or ionotropic glutamate receptor antagonists, bilaterally in DMH and later, with an icv injection of TsTX, or treated only with PBS in both regions. TsTX evoked a marked increase in mean arterial pressure and heart rate in all control rats. Interestingly, injection of muscimol, a GABAA receptor agonist, did not change the pressor and tachycardic responses evoked by TsTX. Remarkably, the injection ionotropic glutamate receptors antagonists in DMH abolished the pressor and the tachycardic response evoked by TsTX. Our data suggest that the central circuit recruited by TsTX, whose activation results in an array of physiological and behavioral alterations, depend on the activation of DMH ionotropic glutamate receptors. Moreover, our data provide new insights on the central mechanisms involved in the development of symptoms in the severe scorpion envenomation syndrome