Commentaries on Viewpoint: The ongoing need for good physiological investigation: Obstructive sleep apnea in HIV patients as a paradigm

The final publication is available via http://dx.doi.org/10.1152/japplphysiol.00989.2014[Abstract] The intriguing paradigm put forth by Darquenne et al. (3) highlighted that improved therapy against human immunodeficiency virus (HIV) has come at the cost of elevated rates of chronic diseases, such as obstructive sleep apnea (OSA) and obesity, during the highly active antiretroviral therapy (HAART) era.Ministerio de Economía y Competitividad; TIN2013-40686-P

Brain

Fil: Campagnole Santos, Maria José. Universidade Federal de Minas Gerais; BrasilFil: Gironacci, Mariela Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Peliky Fontes, Marco Antônio. Universidade Federal de Minas Gerais; Brasi

Asymmetry in the control of cardiac performance by dorsomedial hypothalamus

Dorsomedial hypothalamus (DMH) plays a key role in integrating cardiovascular responses to stress. We have recently reported greater heart rate responses following disinhibition of the right side of the DMH (R-DMH) in anesthetized rats and greater suppression of stress-induced tachycardia following inhibition of the R-DMH in conscious rats [both compared with similar intervention in the left DMH (L-DMH)], suggesting existence of right/left side asymmetry in controlling cardiac chronotropic responses by the DMH. The aim of the present study was to determine whether similar asymmetry is present for controlling cardiac contractility. In anesthetized rats, microinjections of the GABA_A antagonist bicuculline methiodide (BMI; 40 pmol/100 nl) into the DMH-evoked increases in heart rate (HR), left ventricular pressure (LVP), myocardial contractility (LVdP/dt), arterial pressure, and respiratory rate. DMH disinhibition also precipitated multiple ventricular and supraventricular ectopic beats. DMH-induced increases in HR, LVP, LVdP/dt, and in the number of ectopic beats dependent on the side of stimulation, with R-DMH provoking larger responses. In contrast, pressor and respiratory responses did not depend on the side of stimulation. Newly described DMH-induced inotropic responses were rate-, preload- and (largely) afterload-independent; they were mediated by sympathetic cardiac pathway, as revealed by their sensitivity to β-adrenergic blockade. We conclude that recruitment of DMH neurons causes sympathetically mediated positive chronotropic and inotropic effects, and that there is an asymmetry, at the level of the DMH, in the potency to elicit these effects, with R-DMH > L-DMH

The dorsomedial hypothalamus and the central pathways involved in the cardiovascular response to emotional stress.

Psychological stress elicits increases in sympathetic activity accompanied by a marked cardiovascular response. Revealing the relevant central mechanisms involved in this phenomenon could contribute significantly to our understanding of the pathogenesis of stress-related cardiovascular diseases, and the key to this understanding is the identification of the nuclei, pathways and neurotransmitters involved in the organization of the cardiovascular response to stress. The present review will focus specifically on the dorsomedial hypothalamus, a brain region now known to play a primary role in the synaptic integration underlying the cardiovascular response to emotional stress

Sympathoinhibition to Bezold Jarisch reflex is attenuated in protein malnourished rats.

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

Emotional stress and sympathetic activity: contribution of dorsomedial hypothalamus to cardiac arrhythmias

Maintenance of homeostasis in normal or stressful situations depends upon mechanisms controlling autonomic activity. Central requirement for changes in sympathetic output resulting from emotional stress must be adjusted to the input signals from visceral sensory afferent (feedback response) for an optimum cardiovascular performance. There is a large body of evidence indicating that emotional stress can lead to cardiovascular disease. Reviewing the descending pathways from dorsomedial hypothalamus, a key region involved in the cardiovascular response to emotional stress, we discuss the interactions between mechanisms controlling the sympathetic output to the cardiovascular system and the possible implications in cardiovascular disease

Bezold-Jarisch reflex in sino-aortic denervated malnourished rats.

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