Peripheral chemoreceptors and cardiorespiratory coupling: a link to sympatho-excitation

Chronic intermittent hypoxia (CIH) has been identified as a relevant risk factor for the development of enhanced sympathetic outflow and arterial hypertension. Several studies have highlighted the importance of peripheral chemoreceptors for the cardiovascular changes elicited by CIH. However, the effects of CIH on the central mechanisms regulating sympathetic outflow are not fully elucidated. Our research group has explored the hypothesis that the enhanced sympathetic drive following CIH exposure is, at least in part, dependent on alterations in the respiratory network and its interaction with the sympathetic nervous system. In this report, I discuss the changes in the discharge profile of baseline sympathetic activity in rats exposed to CIH, their association with the generation of active expiration and the interactions between expiratory and sympathetic neurones after CIH conditioning. Together, these findings are consistent with the theory that mechanisms of central respiratory–sympathetic coupling are a novel factor in the development of neurogenic hypertension.

Analysis of autonomic modulation after an acute session of resistance exercise at different intensities in chronic obstructive pulmonary disease patients

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Role of cholinergic and adrenergic pathways of the medial septal area in the control of water intake and renal excretion in rats

In this study, we investigated an interaction between noradrenergic and cholinergic pathways of the medial septal area (MSA) on the control of water intake and urinary electrolyte excretion by means of injection of their respective agonists. Noradrenaline (a nonspecific α-adrenergic agonist) and clonidine (an α2-adrenergic agonist), but not phenylephrine (an α1-adrenergic agonist), induced natriuresis and kaliuresis. α-Adrenergic activation had no effect on the natriuresis and kaliuresis induced by carbachol (a cholinergic agonist) and it inhibited the antinatriuresis and antikaliuresis induced by isoproterenol (a ß-adrenergic agonist). Interactions related to volume excretion are complex. α-Adrenergic activation induced a mild diuresis and inhibited the antidiuresis induced by isoproterenol, but phenylephrine combined with carbachol induced antidiuresis. The water intake induced by carbachol was inhibited by clonidine and noradrenaline, but not phenylephrine. These results show an asymmetry in the interaction between α-adrenergic and cholinergic receptors concerning water intake and electrolyte excretion. © 1992.

Role of the adrenergic pathways of the lateral hypothalamus on water intake and pressor response induced by the cholinergic activation of the medial septal area in rats

In the present experiments, we investigated a possible involvement of noradrenergic receptors of the lateral hypothalamus (LH) in the water intake and pressor response induced by cholinergic stimulation of the medial septal area (MSA) in rats. The cholinergic agonist carbachol (2 nmol) injected into the MSA induced water intake and pressor response. The injection of an α2-adrenergic agonist, clonidine (20 and 40 nmol), but not of an α1-adrenergic agonist, phenylephrine (80 and 160 nmol), into the LH inhibits the water intake induced by carbachol injected into the MSA. The injection of clonidine or phenylephrine into the LH produced no change in the MAP increase induced by carbachol injected into the MSA. The present results suggest that adrenergic pathways involving the LH are important for the water intake, but not for the pressor response, induced by cholinergic activation of the MSA. © 1994.

Comparison of Polar(®) RS800G3(™) heart rate monitor with Polar(®) S810i(™) and electrocardiogram to obtain the series of RR intervals and analysis of heart rate variability at rest

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cardiovascular risk and mortality in end-stage renal disease patients undergoing dialysis: sleep study, pulmonary function, respiratory mechanics, upper airway collapsibility, autonomic nervous activity, depression, anxiety, stress and quality of life: a prospective, double blind, randomized controlled clinical trial

Background: Chronic kidney disease (CKD) is one of the most serious public health problems. The increasing prevalence of CKD in developed and developing countries has led to a global epidemic. The hypothesis proposed is that patients undergoing dialysis would experience a marked negative influence on physiological variables of sleep and autonomic nervous system activity, compromising quality of life.Methods/Design: A prospective, consecutive, double blind, randomized controlled clinical trial is proposed to address the effect of dialysis on sleep, pulmonary function, respiratory mechanics, upper airway collapsibility, autonomic nervous activity, depression, anxiety, stress and quality of life in patients with CKD. The measurement protocol will include body weight (kg); height (cm); body mass index calculated as weight/height(2); circumferences (cm) of the neck, waist, and hip; heart and respiratory rates; blood pressures; Mallampati index; tonsil index; heart rate variability; maximum ventilatory pressures; negative expiratory pressure test, and polysomnography (sleep study), as well as the administration of specific questionnaires addressing sleep apnea, excessive daytime sleepiness, depression, anxiety, stress, and quality of life.Discussion: CKD is a major public health problem worldwide, and its incidence has increased in part by the increased life expectancy and increasing number of cases of diabetes mellitus and hypertension. Sleep disorders are common in patients with renal insufficiency. Our hypothesis is that the weather weight gain due to volume overload observed during interdialytic period will influence the degree of collapsibility of the upper airway due to narrowing and predispose to upper airway occlusion during sleep, and to investigate the negative influences of haemodialysis in the physiological variables of sleep, and autonomic nervous system, and respiratory mechanics and thereby compromise the quality of life of patients.

Sympathetic mediation of salivation induced by intracerebroventricular pilocarpine in rats

Central cholinergic activation by pilocarpine induces salivation dependent on the integrity of forebrain areas. The present work investigates the autonomic mediation of this salivation. Pilocarpine (500 nmol/rat) was injected into the lateral ventricle (LV) of tribromoethanol-anesthetized adult male rats. Preweighed cotton balls were inserted into the oral cavity and weighed again 7 min later. ol-adrenoceptor antagonists (3-50 mu mol/kg) prazosin (alpha(1)), yohimbine (alpha(2)) or propranolol (beta) injected intraperitoneally (i.p.) produced, 80%, 20% and 0% inhibition respectively of the LV pilocarpine-induced salivation. Intracerebroventricular injections (160 nmol) of the antagonists did not alter the effects of pilocarpine injected into the LV. Bilateral section of chorda tympani nerve or bilateral sympathetic cervical ganglionectomy produced 0% and 40% inhibition of pilocarpine-induced salivation, respectively. Ganglionectomy did not alter salivation induced by i.p, injection of pilocarpine (4 mu mol/kg). The results indicate that there is a large sympathetic contribution to the salivation induced by central cholinergic activation. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Endogenous hydrogen peroxide in the hypothalamic paraventricular nucleus regulates sympathetic nerve activity responses to L-glutamate

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of thyroid hormone T3 on Myosin-Va expression in the central nervous system

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos agudos do tabagismo sobre a modulação autonômica: análise por meio do plot de poincaré

FUNDAMENTO: O tabagismo altera a função autonômica. OBJETIVO: Investigar os efeitos agudos do tabagismo sobre a modulação autonômica e a recuperação dos índices de variabilidade de frequência cardíaca (VFC) pós-fumo, por meio do plot de Poincaré e índices lineares. MÉTODOS: Foram avaliados 25 fumantes jovens, os quais tiveram a frequência cardíaca analisada, batimento a batimento, na posição sentada, após 8 horas de abstinência, por 30 minutos em repouso, 20 minutos durante o fumo e 30 minutos pós-fumo. Análise de variância para medidas repetidas, seguido do teste de Tukey, ou teste de Friedman seguido do teste de Dunn foram aplicados dependendo da normalidade dos dados, com p < 0,05. RESULTADOS: Durante o fumo, houve redução dos índices SD1 (23,4 ± 9,2 vs 13,8 ± 4,8), razão SD1/SD2 (0,31 ± 0,08 vs 0,2 ± 0,04), RMSSD (32,7 ± 13 vs 19,1 ± 6,8), SDNN (47,6 ± 14,8 vs 35,5 ± 8,4), HFnu (32,5 ± 11,6 vs 19 ± 8,1) e do intervalo RR (816,8 ± 89 vs 696,5 ± 76,3) em relação ao repouso, enquanto que aumentos do índice LFnu (67,5 ± 11,6 vs 81 ± 8,1) e da razão LF/HF (2,6 ± 1,7 vs 5,4 ± 3,1) foram observados. A análise visual do plot mostrou menor dispersão dos intervalos RR durante o fumo. Com exceção da razão SD1/SD2, os demais índices apresentaram recuperação dos valores, 30 minutos após o tabagismo. CONCLUSÃO: O tabagismo produziu agudamente modificações no controle autonômico, caracterizadas por ativação simpática e retirada vagal, com recuperação 30 minutos após o fumo.

Espécies reativas de oxigênio no controle neurovegetativo da pressão arterial

The control of the blood pressure depends on the activity of select groups of neurons present in the central nervous system. Evidence has demonstrated that the redox state (a balance between oxidizing and reducing species) is involved in the control of neuronal activity, which suggests that the redox state can influence the neuronal transmission within the central nervous system acting on the neuronal modulation of biological functions. For instance, the glutamatergic transmission may be widely affected by reactive oxygen species, oxidizing agents that have been extensively investigated due to their involvement in physiological and pathological processes. In the present article, we discuss the main experimental finds that support the hypothesis that reactive oxygen species have important role in physiological (and pathological) modulation of the cardiovascular function through alterations in the sympathetic and parasympathetic system. Therefore, reactive oxygen species can actively participate in the development of cardiovascular diseases like hypertension when the balance in the redox state is disrupted.

Performance of children with learning difficulties in fine motor function and handwriting

This study aimed to compare and characterize the fine, sensory and perceptive function performance and handwriting quality between students with learning difficulties and students with good academic performance. Methods: This study comprised 192 students from 2nd to 4th grades, both genders, whose ages ranged from 7 to 11 years old. The students were distributed into: GI, GII, GIII and GIV, comprising 96 students with learning difficulties, and groups GV, GVI, GVII, GVIII comprising 96 students with good academic performance. The students were submitted to evaluation of fine motor, sensorial and perception functions and handwriting evaluation under dictation. Results: The results showed that the students with learning difficulties, from 1st to 3rd grade, had lower performance on tests of fine motor, sensory and perceptive function, when compared to the students with good academic performance in the same grade; the students from 4th grade, both groups, did not show changes on fine motor, sensory and perceptive function; and only the students of GII showed dysgraphia. Conclusions: the results presented in this study suggest that the qualitative aspects of fine motor, sensory and perceptive skills reflect the integrity and maturity of central nervous system and can probably play an important role in early diagnosis of development disorders and consequently prevent academic disorders such as handwriting performance.

Efeito antinociceptivo, gastrointestinal e na atividade locomotora espontânea da administração intravenosa e metadona em equinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da variabilidade da frequência cardíaca em cães

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Differential effects of variation in athletes training on myocardial morphophysiological adaptation in men: Focus on I-123-MIBG assessed myocardial sympathetic activity

High intensity systematic physical training leads to myocardial morphophysiological adaptations. The goal of this study was to investigate if differences in training were correlated with differences in cardiac sympathetic activity.58 males (19-47 years), were divided into three groups: strength group (SG), (20 bodybuilders), endurance group (EG), (20 endurance athletes), and a control group (CG) comprising 18 healthy non-athletes. Cardiac sympathetic innervation was assessed by planar myocardial I-123-metaiodobenzylguanidine scintigraphy using the early and late heart to mediastinal (H/M) ratio, and washout rate (WR).Left ventricular mass index was significantly higher both in SG (P < .001) and EG (P = .001) compared to CG without a statistical significant difference between SG and EG (P = .417). The relative wall thickness was significantly higher in SG compared to CG (P < .001). Both left ventricular ejection fraction and the peak filling rate showed no significant difference between the groups. Resting heart rate was significantly lower in EG compared to CG (P = .006) and SG (P = .002). The late H/M ratio in CG was significantly higher compared to the late H/M for SG (P = .003) and EG (P = .004). However, WR showed no difference between the groups. There was no significant correlation between the parameters of myocardial sympathetic innervation and parameters of left ventricular function.Strength training resulted in a significant increase in cardiac dimensions. Both strength and endurance training seem to cause a reduction in myocardial sympathetic drive. However, myocardial morphological and functional adaptations to training were not correlated with myocardial sympathetic activity.