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Charlotte W Usselman, Chantelle A Nielson, Torri A Luchyshyn, Tamara I Gimon, Nicole S Coverdale, Stan H M Van Uum, J Kevin Shoemaker
We tested the hypothesis that sympathetic responses to baroreceptor unloading may be affected by circulating sex hormones. During lower body negative pressure at -30, -60, and -80 mmHg, muscle sympathetic nerve activity (MSNA), heart rate and blood pressure were recorded in women taking (n=8) and not taking (n=9) hormonal contraceptives. All women were tested twice, once during the low hormone phase (i.e. the early follicular phase of the menstrual cycle and the placebo phase of hormonal contraceptive use), and again during the high hormone phase (i...
October 12, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Min-Zhu Zhao, Yong-Guo Li, Peng Zhang, Jin-Cheng Xiong, Shi-Sheng Zhu, Xuan Xiao, Jian-Bo Li
In forensic medicine, the diagnosis of death due to neurogenic shock is considered to be an aporia, as lacking objective indicators and presenting atypical symptoms in autopsy. Medico-legal disputes and complaints occasionally result from this ambiguity. To explore potential objective indicators of neurogenic shock, we set up a model of neurogenic shock by applying an external mechanical force on the carotid sinus baroreceptor in rabbits. The serum atrial natriuretic peptide (ANP) level was measured by radioimmunoassay in the control group (n = 8), survival group (n = 15) and death group (n = 5) both before and after the insult...
October 10, 2016: International Journal of Legal Medicine
Jacob Sturdy, Johnny T Ottesen, Mette S Olufsen
The baroreceptor neurons serve as the primary transducers of blood pressure for the autonomic nervous system and are thus critical in enabling the body to respond effectively to changes in blood pressure. These neurons can be separated into two types (A and C) based on the myelination of their axons and their distinct firing patterns elicited in response to specific pressure stimuli. This study has developed a comprehensive model of the afferent baroreceptor discharge built on physiological knowledge of arterial wall mechanics, firing rate responses to controlled pressure stimuli, and ion channel dynamics within the baroreceptor neurons...
October 5, 2016: Journal of Computational Neuroscience
Yusuke Kobayashi, Hideo Kobayashi, Hiroaki Ishiguro, Keisuke Yatsu, Tetsuya Fujikawa, Satoshi Umemura
OBJECTIVE: Though both carotid bulb and aortic arch are known to play important roles in regulation of blood pressure through modulation in baroreflex function, few studies have investigated the association of carotid bulb atherosclerosis and large arterial stiffness and orthostatic blood pressure change. DESIGN AND METHOD: Patients with metabolic disorder such as hypertension, dyslipidemia and diabetes mellitus underwent measurement of segment-specific carotid intima-media thickness (IMT) (as an index of atherosclerosis of carotid bulb), cardio-ankle vascular index (CAVI) (as an index for large arterial stiffness), heart rate variability (HRV) (as an index of baroreflex function) and sit-to-stand orthostatic blood pressure change (as a simple method for detecting orthostatic hypotension)...
September 2016: Journal of Hypertension
George Bakris
Resistant hypertension is defined as a blood pressure above 140/90 mmHg despite adherence to a combination of at least three optimally dosed antihypertensive medications, one of which is a diuretic. Chronic kidney disease (CKD) is one of the more common patient comorbidities associated with resistant hypertension. Recommended low-salt diet and triple antihypertensive drug regimens that include a diuretic, should be complemented by the sequential addition of other antihypertensive drugs. CKD is associated with premature vascular ageing, characterized by accelerated arteriosclerosis or atherosclerosis and endothelial dysfunction...
September 2016: Journal of Hypertension
Mehrangiz Khanmoradi, Ali Nasimi
The hypothalamic paraventricular nucleus (PVN) plays a role in cardiovascular regulation through vasopressin release and sympathetic system. The PVN contains angiotensin II (AngII) immunoreactive cells, fibers and AngII receptors. We have already shown that microinjection of AngII into PVN produced a pressor response concomitant with an increase in firing rate of some PVN neurons. This study was performed to find if PVN AngII plays a regulatory function during hypotension. Hypovolemic-hypotension was induced and the possible role of the PVN AngII in returning arterial pressure toward normal was assessed by monitoring cardiovascular response and single-unit activity of the PVN neurons...
September 13, 2016: Neuroscience Research
Eva On-Chai Lau, Chun-Yin Lo, Yifei Yao, Arthur Fuk-Tat Mak, Liwen Jiang, Yu Huang, Xiaoqiang Yao
Arterial baroreceptors are mechanical sensors that detect blood pressure changes. It has long been suggested that the two arterial baroreceptors, aortic and carotid baroreceptors, have different pressure sensitivities. However, there is no consensus as to which of the arterial baroreceptors are more sensitive to changes in blood pressure. In the present study, we employed independent methods to compare the pressure sensitivity of the two arterial baroreceptors. Firstly, pressure-activated action potential firing was measured by whole-cell current clamp with a high-speed pressure clamp system in primary cultured baroreceptor neurons...
2016: Frontiers in Physiology
Caroline Gusson Shimoura, Gisele Silvério Lincevicius, Erika Emy Nishi, Adriana Castello Costa Girardi, Karin Argenti Simon, Cassia de Toledo Bergamaschi, Ruy Ribeiro Campos
BACKGROUND: Renovascular hypertension (2-kidney 1-clip model (2K1C)) is characterized by renin-angiotensin system (RAS) activation. Increased Angiotensin II (AngII) leads to sympathoexcitation, oxidative stress, and alterations in sodium and water balance. AIM: The aim of this study was to evaluate whether a discrete increase in sodium chloride intake in 2K1C rats leads to changes in cardiovascular and autonomic function, oxidative stress, and renin angiotensin aldosterone system...
September 14, 2016: American Journal of Hypertension
Yang Liu, Di Wu, Mei-Yu Qu, Jian-Li He, Mei Yuan, Miao Zhao, Jian-Xin Wang, Jian He, Lu-Qi Wang, Xin-Jing Guo, Meng Zuo, Shu-Yang Zhao, Mei-Na Ma, Jun-Nan Li, Weinian Shou, Guo-Fen Qiao, Bai-Yan Li
BACKGROUND: Molecular and cellular mechanisms of neuropeptide-Y (NPY)-mediated gender-difference in blood pressure (BP) regulation are largely unknown. METHODS: Baroreceptor sensitivity (BRS) was evaluated by measuring the response of BP to phenylephrine/nitroprusside. Serum NPY concentration was determined using ELISA. The mRNA and protein expression of NPY receptors were assessed in tissue and single-cell by RT-PCR, immunoblot, and immunohistochemistry. NPY was injected into the nodose while arterial pressure was monitored...
September 7, 2016: Oncotarget
Mateus R Amorim, Leni G H Bonagamba, George M P R Souza, Davi J A Moraes, Benedito H Machado
Sino-aortic denervated (SAD) rats present mean arterial pressure (MAP) similar to control rats. Since respiration modulates MAP, we hypothesized that conscious SAD rats present respiratory changes associated with the normal MAP. In this study we evaluated the cardiovascular and respiratory activities and arterial blood gases in control and SAD rats. Male juvenile Wistar rats (P19-P21) were submitted to SAD, sham surgery, or selective carotid bodies removal (CBX) and the three groups were evaluated 10 days after the surgery (SAD, n = 21, Sham, n = 18, CBX, n = 13)...
September 12, 2016: Experimental Physiology
Jasdeep Kaur, Alberto Alvarez, Hanna W Hanna, Abhinav C Krishnan, Danielle Senador, Tiago M Machado, Yasir H Altamimi, Abe T Lovelace, Maryetta D Dombrowski, Marty D Spranger, Donal O'Leary
The muscle metaboreflex and arterial baroreflex regulate arterial pressure through distinct mechanisms. During submaximal exercise muscle metaboreflex activation (MMA) elicits a pressor response virtually solely by increasing cardiac output (CO) while baroreceptor unloading increases mean arterial pressure (MAP) primarily through peripheral vasoconstriction. The interaction between the two reflexes when activated simultaneously has not been well established. We activated the muscle metaboreflex in chronically instrumented canines during dynamic exercise (via graded reductions in hindlimb blood flow; HLBF) followed by simultaneous baroreceptor unloading (via bilateral carotid occlusion; BCO)...
September 9, 2016: American Journal of Physiology. Heart and Circulatory Physiology
M H Abdulla, M Duff, H Swanton, E J Johns
AIM: This study investigated the effect of renal bradykinin B1 and B2 receptor blockade on the high- and low-pressure baroreceptor reflex regulation of renal sympathetic nerve activity (RSNA) in rats with cisplatin-induced renal failure. METHODS: Cisplatin (5 mg/kg) or saline was given intraperitoneally 4 days prior to study. Following chloralose/urethane anaesthesia, rats were prepared for measurement of mean arterial pressure (MAP), heart rate and RSNA and received intrarenal infusions of either Lys-[des-Arg(9) , Leu(8) ]-bradykinin (LBK), a bradykinin B1 receptor blocker, or bradyzide (BZ), a bradykinin B2 receptor blocker...
November 2016: Acta Physiologica
T Meller, F Stiehm, R Malinowski, K Thieme
The interaction of cardiovascular dynamics and pain perception is an important component of intrinsic pain regulation. In healthy subjects acute pain stimuli cause increased sympathetic arousal and increased mean arterial pressure. Arterial baroreceptors sense phasic blood pressure changes and relay the information to the lower brainstem via the dorsomedial nucleus tractus solitarius (dmNTS). Projections in the brainstem and also higher cortical areas result in elevation of blood pressure as part of the autonomic nervous system as well as modulation of sleep, anxiety and pain...
October 2016: Der Schmerz
Nicola Maschietto, Luca Semplicini, Giulio Ceolotto, Arianna Cattelan, Helen Poser Dvm, Ilaria Iacopetti, Gabriele Gerardi, Giulia Maria De Benedictis, Tommaso Pilla, Daniele Bernardini, Luca Aresu, Stefania Rizzo, Cristina Basso, Andrea Semplicini, Ornella Milanesi
BACKGROUND: Stent implantation is the treatment of choice for adolescents and adults with aortic coarctation (CoAo). Despite excellent short-term results, 20%-40% of the patients develop arterial hypertension later in life, which was attributed to inappropriate response of the aortic baroreceptors to increased stiffness of the ascending aorta (ASAO), either congenital or induced by CoAo repair. In particular, it has been hypothesized that stent itself may cause or sustain hypertension...
September 7, 2016: Congenital Heart Disease
Thales C Barbosa, Lauro C Vianna, Takeshi Hashimoto, Lonnie Grove Petersen, Niels D Olesen, Hayato Tsukamoto, Henrik Sørensen, Shigehiko Ogoh, Antonio Claudio L Nóbrega, Niels H Secher
Arterial baroreflex function is important for blood pressure control during exercise, but its contribution to cardiovascular adjustments at the onset of cycling exercise remains unclear. Fifteen healthy male subjects (24 ± 1 years) performed 45-s trials of low- and moderate-intensity cycling, with carotid baroreceptor stimulation by neck suction at -60 Torr applied 0-5, 10-15, and 30-35 s after the onset of exercise. Cardiovascular responses to neck suction during cycling were compared to those obtained at rest...
August 31, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
J Menne, R Wachter
Invasive treatment methods-more specifically renal denervation and baroreceptor activator therapy-have been used for the treatment of therapy-resistant hypertension for several years now. In particular, renal denervation has aroused great interest because it was easy to perform and the first studies provided very promising results. Meanwhile, however, three randomized, blinded studies have been published, and none showed a significant benefit of renal denervation compared to a sham procedure. In addition, in several studies it was demonstrated that intensification of drug therapy, particularly with spironolactone, is at least comparable...
September 2016: Der Internist
C R Newey, J R Martin
In a rat model, the baroreceptor reflex can be assessed by graded infusions of either phenylephrine or sodium nitroprusside with continuous hemodynamic monitoring. Microinjection of the cholinergic agonist carbachol (CCh) into the posterior hypothalamic nucleus (PHN) evokes an increase in mean arterial pressure and a change in heart rate. Lower doses of CCh evoke only tachycardia, whereas middle and higher doses evoke a biphasic change in heart rate of tachycardia followed by bradycardia. The bradycardia following the microinjection of CCh into the PHN can be attenuated by the previous administration of the vasopressin V1 receptor antagonist [d(CH2 )5 Tyr(Me)] arginine vasopressin (AVPX)...
January 2016: Autonomic & Autacoid Pharmacology
Michael S Lauer
No abstract text is available yet for this article.
August 19, 2016: Circulation Research
Nikhil Kansal, Daniel G Clair, Deborah A Jaye, Avram Scheiner
OBJECTIVE: Continuous stimulation of the carotid baroreceptors has been shown to evoke a sustained systolic blood pressure (SBP) reduction in hypertensive subjects. This study conducted a detailed mapping of the SBP and heart rate response to electrical stimulus at different locations in the carotid sinus region in patients undergoing a carotid endarterectomy (CEA). METHODS: The Carotid Sinus Autonomic Response Mapping (C-Map) Study is a multicenter, prospective, non-randomized, acute feasibility study conducted in 10 hypertensive subjects undergoing CEA...
July 30, 2016: Autonomic Neuroscience: Basic & Clinical
Kanji Matsukawa, Kei Ishii, Ryota Asahara, Mitsuhiro Idesako
Our laboratory has reported that central command blunts the sensitivity of aortic baroreceptor-heart rate (HR) reflex at the onset of voluntary static exercise in animals. We have examined whether baroreflex control of cardiac sympathetic nerve activity (CSNA) and/or cardiovagal baroreflex sensitivity are altered at the onset of spontaneously occurring motor behavior, which was monitored with tibial nerve activity in paralyzed, decerebrate cats. CSNA exhibited a peak increase (126 ± 17%) immediately after the exercise onset, followed by increases in HR and mean arterial pressure (MAP)...
August 18, 2016: Journal of Applied Physiology
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