-
The Journal of Clinical Investigation Jul 2020Mechanical stretch of baroreceptors in the wall of the aortic arch and carotid sinus initiates autonomic reflexes to change heart rate and blood pressure for...
Mechanical stretch of baroreceptors in the wall of the aortic arch and carotid sinus initiates autonomic reflexes to change heart rate and blood pressure for cardiovascular homeostasis. In this issue of the JCI, Lu et al. show that tentonin 3 (TTN3), a recently identified stretch-sensitive ion channel, was present at the vagus afferent nerve endings innervating the aortic arch to function as a baroreceptor. This study expands the molecular profiles of baroreceptors and provides new insights into molecular mechanisms underlying the regulation of cardiovascular functions through baroreceptor function.
Topics: Aorta, Thoracic; Blood Pressure; Carotid Sinus; Ion Channels; Pressoreceptors
PubMed: 32484454
DOI: 10.1172/JCI138120 -
Phlebology May 2015This study is the first in a series investigating the relationship between autonomic nervous system dysfunction and chronic cerebrospinal venous insufficiency in...
OBJECTIVE
This study is the first in a series investigating the relationship between autonomic nervous system dysfunction and chronic cerebrospinal venous insufficiency in multiple sclerosis patients. We screened patients for the combined presence of the narrowing of the internal jugular veins and symptoms of autonomic nervous system dysfunction (fatigue, cognitive dysfunction, sleeping disorders, headache, thermal intolerance, bowel/bladder dysfunction) and determined systolic and diastolic blood pressure responses to balloon angioplasty.
METHODS
The criteria for eligibility for balloon angioplasty intervention included ≥ 50% narrowing in one or both internal jugular veins, as determined by the magnetic resonance venography, and ≥ 3 clinical symptoms of autonomic nervous system dysfunction. Blood pressure was measured at baseline and post-balloon angioplasty.
RESULTS
Among patients who were screened, 91% were identified as having internal jugular veins narrowing (with obstructing lesions) combined with the presence of three or more symptoms of autonomic nervous system dysfunction. Balloon angioplasty reduced the average systolic and diastolic blood pressure. However, blood pressure categorization showed a biphasic response to balloon angioplasty. The procedure increased blood pressure in multiple sclerosis patients who presented with baseline blood pressure within lower limits of normal ranges (systolic ≤ 105 mmHg, diastolic ≤ 70 mmHg) but decreased blood pressure in patients with baseline blood pressure above normal ranges (systolic ≥ 130 mmHg, diastolic ≥ 80 mmHg). In addition, gender differences in baseline blood pressure subcategories were observed.
DISCUSSION
The coexistence of internal jugular veins narrowing and symptoms of autonomic nervous system dysfunction suggests that the two phenomena may be related. Balloon angioplasty corrects blood pressure deviation in multiple sclerosis patients undergoing internal jugular vein dilation. Further studies should investigate the association between blood pressure deviation and internal jugular veins narrowing, and whether blood pressure normalization affects Patient's clinical outcomes.
Topics: Adult; Aged; Angioplasty, Balloon; Autonomic Nervous System Diseases; Blood Pressure; Constriction, Pathologic; Female; Humans; Jugular Veins; Male; Middle Aged; Multiple Sclerosis; Pressoreceptors; Severity of Illness Index; Sex Factors; Symptom Assessment; Treatment Outcome; Venous Insufficiency
PubMed: 24255092
DOI: 10.1177/0268355513512824 -
Indian Journal of Pharmacology 2019The objective of the study is to develop an automatic drug infusion control system during cardiovascular surgery.
OBJECTIVES
The objective of the study is to develop an automatic drug infusion control system during cardiovascular surgery.
MATERIALS AND METHODS
Based on the clinical drug dosage analysis, the modeling of cardiovascular system with baroreceptor model is mathematically modeled using compartmental approach, considering the relationship between the volume and flow rate of blood during each heartbeat. This model is then combined with drug modeling of noradrenaline and nitroglycerine by deriving the volume and drug mass concentration equations, based on pharmacokinetics and pharmacodynamics of the drugs. The closed-loop patient models are derived from the open-loop data obtained from the physiology-drug model with covariate as age. The proportional-integral controller is designed based on optimal values obtained from bacterial foraging-oriented particle swarm optimization algorithm. The controllers are implemented individually for each control variable such as aortic pressure and cardiac output (CO), irrespective of varying weights based on the relative gain array analysis which depicts the maximum influence of cardiac drugs on control variables.
RESULTS
The physiology-drug model output responses are simulated using MATLAB. The controlled responses of aortic pressure and CO with infusion rate of cardiac drugs are obtained. The robustness of the controller is checked by introducing variations in cardiovascular model parameters. The efficiency of the controller during normal and abnormal conditions is compared using time domain analysis.
CONCLUSIONS
The controller design was efficient and can be further improved by designing switching-based controllers.
Topics: Arterial Pressure; Cardiac Output; Cardiovascular Agents; Humans; Infusions, Intravenous; Models, Cardiovascular; Nitroglycerin; Norepinephrine; Pressoreceptors
PubMed: 31031469
DOI: 10.4103/ijp.IJP_612_18 -
Medical Hypotheses Jan 2020The carotid sinus is a dilated area at the base of the internal carotid artery of humans and is located immediately superior to the bifurcation of the internal and...
The carotid sinus is a dilated area at the base of the internal carotid artery of humans and is located immediately superior to the bifurcation of the internal and external carotid arteries. It is widely accepted, in the fields of medicine and physiology, to function as a baroreceptor in its central control role. This paper presents a hypothesis challenging this paradigm - that the carotid sinus functions by detecting oscillations at the vessel wall which result from shear stress due to vortical flow. This is contrary to conventional thinking which presumes that the carotid sinus responds to blood pressure or wall pressure. Our hypothesis is based on anatomy, physiology and physical properties of fluid which make the sinus the area of highest vorticity. Utilizing magnetic resonance angiograms of undiseased carotid vessels, we computed the oscillatory shear index (OSI) via a computational fluid dynamics simulation of flow. This region of highest OSI coincides with the area where the nerve to the carotid sinus lies within the vessel wall. Accordingly, the hypothesis is that the carotid sinus acts as a mechanotransducer of wall shear stress oscillation and not as a baroreceptor.
Topics: Baroreflex; Carotid Artery, External; Carotid Artery, Internal; Carotid Sinus; Computer Simulation; Hemorheology; Humans; Magnetic Resonance Angiography; Mechanotransduction, Cellular; Models, Cardiovascular; Pressoreceptors; Stress, Mechanical
PubMed: 31726427
DOI: 10.1016/j.mehy.2019.109441 -
CNS Neuroscience & Therapeutics Mar 2022To understand the direct impact of bradykinin in autonomic control of circulation through baroreflex afferent pathway.
AIM
To understand the direct impact of bradykinin in autonomic control of circulation through baroreflex afferent pathway.
METHODS
The mean arterial pressure (MAP) was monitored while bradykinin and its agonists were applied via nodose (NG) microinjection, the expression of bradykinin receptors (BRs) in the NG (1 -order) and nucleus tractus solitarius (NTS, 2 -order) were tested in adult male, age-matched female, and ovariectomized rats under physiological and hypertensive conditions. Additionally, bradykinin-induced depolarization was also tested in identified baroreceptor and baroreceptive neurons using whole-cell patch-clamp technique.
RESULTS
Under physiological condition, bradykinin-induced dose- and estrogen-dependent reductions of MAP with lower estimated EC in females. B R agonist mediated more dramatic MAP reduction with long-lasting effect compared with B R activation. These functional observations were consistent with the molecular and immunostaining evidences. However, under hypertensive condition, the MAP reduction was significantly less dramatic in N -Nitro-L-Arginine-methyl ester (L-NAME) induced secondary and spontaneous hypertension rats in males compared with female rats. Electrophysiological data showed that bradykinin-elicited concentration-dependent membrane depolarization with discharges during initial phase in identified myelinated Ah-types baroreceptor neurons, not myelinated A-types; while, higher concentration of bradykinin was required for depolarization of unmyelinated C-types without initial discharges.
CONCLUSION
These datasets have demonstrated for the first time that bradykinin mediates direct activation of baroreflex afferent function to trigger estrogen-dependent depressor response, which is due mainly to the direct activation/neuroexcitation of female-specific myelinated Ah-type baroreceptor neurons leading to a sexual dimorphism in parasympathetic domination of blood pressure regulation via activation of B R/B R expression in baroreflex afferent pathway.
Topics: Animals; Baroreflex; Bradykinin; Estrogens; Female; Hypertension; Male; Neurons; Pressoreceptors; Rats; Rats, Inbred SHR
PubMed: 34964272
DOI: 10.1111/cns.13792 -
Advances in Physiology Education Sep 2018We describe a simple, cost-effective experiment to demonstrate cardiovascular integration of heart rate and blood pressure to accommodate the environmental and dietary...
We describe a simple, cost-effective experiment to demonstrate cardiovascular integration of heart rate and blood pressure to accommodate the environmental and dietary factors of gravity and caffeine. Specific learning objectives associated with this include understanding the effects of posture on blood pressure and heart rate, coupled with the role of caffeine in modifying this response. Inclusion of ECG measurements, coupled with heart rate variability analysis, added a demonstration of the contribution made by the autonomic nervous system under these conditions. We clearly demonstrate that the cardiac work, estimated as rate-pressure product, necessary to undertake the transition from supine to standing, is fixed for a given group of subjects. However, the individual contribution of heart rate and systolic pressure to the cardiac workload is subject to the external factors of gravity and caffeine. Such an activity also demonstrates additional benefits, including unstructured teaching opportunities to augment classroom learning associated with integrative physiology and also the discussion of ethical issues with regard to human experimentation.
Topics: Adolescent; Adult; Blood Pressure; Caffeine; Diet; Female; Gravitation; Heart Rate; Humans; Male; Physiology; Posture; Pressoreceptors; Young Adult
PubMed: 29972055
DOI: 10.1152/advan.00003.2017 -
American Journal of Physiology. Heart... Aug 2020Changes in the arterial baroreflex arc contribute to elevated sympathetic outflow and altered reflex control of blood pressure with human aging. Using ultrasound and... (Comparative Study)
Comparative Study
Changes in the arterial baroreflex arc contribute to elevated sympathetic outflow and altered reflex control of blood pressure with human aging. Using ultrasound and sympathetic microneurography (muscle sympathetic nerve activity, MSNA) we investigated the relationships between aortic and carotid artery wall tension (indices of baroreceptor activation) and the vascular sympathetic baroreflex operating point (OP; MSNA burst incidence) in healthy, normotensive young ( = 27, 23 ± 3 yr) and middle-aged men ( = 22, 55 ± 4 yr). In young men, the OP was positively related to the magnitude and rate of unloading and time spent unloaded in the aortic artery ( = 0.56, 0.65, and 0.51, = 0.02, 0.003, and 0.03), but not related to the magnitude or rate of unloading or time spent unloaded in the carotid artery ( = -0.32, -0.07, and 0.06, = 0.25, 0.81, and 0.85). In contrast, in middle-aged men, the OP was not related to either the magnitude or rate of unloading or time spent unloaded in the aortic ( = 0.22, 0.21, and 0.27, = 0.41, 0.43, and 0.31) or carotid artery ( = 0.06, 0.28, and -0.01; = 0.48, 0.25, and 0.98). In conclusion, in young men, aortic unloading mechanics may play a role in determining the vascular sympathetic baroreflex OP. In contrast, in middle-aged men, barosensory vessel unloading mechanics do not appear to determine the vascular sympathetic baroreflex OP and, therefore, do not contribute to age-related arterial baroreflex resetting and increased resting MSNA. We assessed the influence of barosensory vessel mechanics (magnitude and rate of unloading and time spent unloaded) as a surrogate for baroreceptor unloading. In young men, aortic unloading mechanics are important in regulating the operating point of the vascular sympathetic baroreflex, whereas in middle-aged men, these arterial mechanics do not influence this operating point. The age-related increase in resting muscle sympathetic nerve activity does not appear to be driven by altered baroreceptor input from stiffer barosensory vessels.
Topics: Adult; Age Factors; Aging; Aorta; Arterial Pressure; Baroreflex; Carotid Arteries; Heart Rate; Homeostasis; Humans; Male; Middle Aged; Muscle, Skeletal; Pressoreceptors; Time Factors; Ultrasonography; Young Adult
PubMed: 32648822
DOI: 10.1152/ajpheart.00265.2020 -
Hypertension (Dallas, Tex. : 1979) Jul 2016Carotid bodies play a critical role in protecting against hypoxemia, and their activation increases sympathetic activity, arterial pressure, and ventilation, responses...
Carotid bodies play a critical role in protecting against hypoxemia, and their activation increases sympathetic activity, arterial pressure, and ventilation, responses opposed by acute stimulation of the baroreflex. Although chemoreceptor hypersensitivity is associated with sympathetically mediated hypertension, the mechanisms involved and their significance in the pathogenesis of hypertension remain unclear. We investigated the chronic interactions of these reflexes in dogs with sympathetically mediated, obesity-induced hypertension based on the hypothesis that hypoxemia and tonic activation of carotid chemoreceptors may be associated with obesity. After 5 weeks on a high-fat diet, the animals experienced a 35% to 40% weight gain and increases in arterial pressure from 106±3 to 123±3 mm Hg and respiratory rate from 8±1 to 12±1 breaths/min along with hypoxemia (arterial partial pressure of oxygen=81±3 mm Hg) but eucapnia. During 7 days of carotid baroreflex activation by electric stimulation of the carotid sinus, tachypnea was attenuated, and hypertension was abolished before these variables returned to prestimulation values during a recovery period. After subsequent denervation of the carotid sinus region, respiratory rate decreased transiently in association with further sustained reductions in arterial partial pressure of oxygen (to 65±2 mm Hg) and substantial hypercapnia. Moreover, the severity of hypertension was attenuated from 125±2 to 116±3 mm Hg (45%-50% reduction). These findings suggest that hypoxemia may account for sustained stimulation of peripheral chemoreceptors in obesity and that this activation leads to compensatory increases in ventilation and central sympathetic outflow that contributes to neurogenically mediated hypertension. Furthermore, the excitatory effects of chemoreceptor hyperactivity are abolished by chronic activation of the carotid baroreflex.
Topics: Animals; Carotid Body; Chemoreceptor Cells; Diet, High-Fat; Disease Models, Animal; Dogs; Electric Stimulation; Hypertension; Hypoxia; Obesity; Pressoreceptors; Random Allocation; Tachypnea; Treatment Outcome
PubMed: 27160198
DOI: 10.1161/HYPERTENSIONAHA.116.07232 -
The Journal of Maternal-fetal &... Dec 2023Baroreflex is a regulatory mechanism that slows the fetal heart rate. This study aimed to investigate the effects of lipopolysaccharide (LPS)-induced endotoxemia on...
OBJECTIVE
Baroreflex is a regulatory mechanism that slows the fetal heart rate. This study aimed to investigate the effects of lipopolysaccharide (LPS)-induced endotoxemia on fetal baroreceptor sensitivity in preterm fetal sheep.
METHODS
The changes in fetal baroreceptor sensitivity were measured in seven chronically instrumented preterm fetal sheep. Fetal baroreceptor sensitivity was measured in three phases: (A) control phase, defined as the 24 h before the first injection of LPS; (B) acute phase, defined as the 24 h between the first and second injections of LPS; and (C) fetal acidosis phase, defined as the time from the second LPS injection until intrauterine fetal death. Histological examinations of the fetal membrane and umbilical cord were also conducted.
RESULTS
Each fetus developed metabolic acidosis after the second injection of LPS. The fetuses died 24.7 (SD = 6.1) hours after the second injection of LPS. Both the umbilical cord and fetal membranes showed histological evidence of severe inflammation. In total, 163 fetal baroreceptor measurements were performed in this experiment (A, = 77 times; B, = 60 times; C, = 26 times). Fetal baroreceptor sensitivity showed significant differences in all three phases (A: 2.7 [SD = 0.2]; B: 2.5 [SD = 0.2]; and C: 1.5 [SD = 0.2]). Post hoc tests showed that baroreceptor sensitivity in the acidosis phase had decreased significantly compared to that in the control and acute phases (<.001 and =.002, respectively).
CONCLUSIONS
Fetal baroreceptor sensitivity decreased during fetal acidosis induced by LPSs.
Topics: Pregnancy; Female; Humans; Sheep; Animals; Lipopolysaccharides; Pressoreceptors; Fetus; Inflammation; Fetal Diseases; Acidosis; Heart Rate, Fetal
PubMed: 36443245
DOI: 10.1080/14767058.2022.2150392 -
Journal of Atherosclerosis and... Apr 2024The carotid sinuses and aortic arch are baroreceptor-resident arteries (BRAs) and atherosclerosis-susceptible sites of brain-supplying arteries, which would impair...
Evaluating Total Atherosclerosis Burden of Baroreceptor-Resident Arteries after Ischemic Cerebrovascular Disease for Identifying Patients with Heavy Coronary Atherosclerosis Burden.
AIM
The carotid sinuses and aortic arch are baroreceptor-resident arteries (BRAs) and atherosclerosis-susceptible sites of brain-supplying arteries, which would impair baroreflex-mediated blood pressure (BP) regulation and prompt coronary atherosclerosis. We sought to determine the relationship between total atherosclerosis burden (TAB) of BRAs and coronary atherosclerosis burden (AB) in patients with ischemic cerebrovascular disease (ICVD) and explore the potential contribution of BP profiles to this relationship.
METHODS
In this cross-sectional analysis of patients with ICVD who simultaneously undertook computed tomography angiography and 24-hour ambulatory BP monitoring, TAB of BRAs was scored based on the atherosclerotic vessel circumference ratio of the carotid sinuses and aortic arch, while the ABs of the intracranial, cervical, aortic, and coronary arteries were scored based on stenosis severity and plaque complexity as routine.
RESULTS
Among the 230 patients analyzed, coronary AB was significantly correlated with TAB of BRAs, independently of, and more tightly than the ABs of the intracranial, cervical, and aortic arteries, and the stenosis- and complexity-based AB of BRA-located arteries (bilateral common and extracranial internal carotid arteries and aortic arch). Both coronary AB and TAB of BRAs were negatively associated with the night-to-day BP dipping ratios, which was quite different from the relationship between intracranial AB and 24-hour BP characteristics. These findings were also true for patients with ICVD without a history of coronary artery disease.
CONCLUSION
Evaluating TAB of BRAs might provide a new link between atherosclerosis of brain- and heart-supplying arteries, connected partially by BP circadian rhythm. It might facilitate identifying patients with ICVD with heavy coronary AB and comprehensively managing vascular risk.
Topics: Humans; Coronary Artery Disease; Stroke; Constriction, Pathologic; Pressoreceptors; Cross-Sectional Studies; Risk Factors; Atherosclerosis; Arteries
PubMed: 37866928
DOI: 10.5551/jat.64457