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Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Chiropractic, Durban University of Technology, 2009. / The Effect of Cervical and Thoracic Spinal Manipulations on Blood Pressure in Normotensive Males. BACKGROUND A distinguishing feature of chiropractic is manipulation that is a load delivered by hand, to specific tissues (usually a short lever bony prominence) with therapeutic intent. Chiropractic spinal manipulation results in somatovisceral reflexes, which can affect the cardiovascular system and thereby reduce blood pressure. Areas of the spine known to cause such effects are the upper cervical region and the upper thoracic region. Increased blood pressure/hypertension is a global disorder. The incidence is increasing and leads to complications of cardiovasular disease and cerebral vascular accidents OBJECTIVES The objectives of the study were to determine whether spinal manipulation evokes somatovisceral reflexes and causes a reduction in blood pressure following an atlanto-axial (C0/C1), and Thoracic segments one to five manipulations (T1-T5). METHODS Forty, asymptomatic, normotensive males between the ages of 20 – 35 years of age participated in the study. All subjects underwent four consecutive days of intervention. Day one was sham laser. Day two was C0/C1 spinal manipulation. Day three was T1-T5 thoracic manipulation. Day four was a combination of C0/C1 and T1-T5 spinal manipulations. RESULTS The results of this study suggest that blood pressure decreases following a cervical or a thoracic manipulation, however a combination of the manipulations does not have a significant cumulative effect on the reduction of blood pressure. iv CONCLUSIONS Somatovisceral reflexes are evoked following a spinal manipulation, causing a reduction in blood pressure after an upper cervical or upper thoracic manipulation. Neurophysiological effects occurring as a result of spinal manipulation may inhibit or excite somatosomatic reflexes, which changes heart rate and blood pressure.

Prolonged exposure to microgravity is known to invoke physiological changes which predispose individuals to orthostatic intolerance upon readaptation to the earth's gravitational field. Attenuated baroreflex responsiveness has been implicated in contributing to this inability to withstand orthostatic stress. To test this hypothesis, eight individuals were exposed to 15 days of simulated microgravity exposure using the 6° head-down bed rest model. Prior to, and after the simulated microgravity exposure, the following were assessed: a) aortic baroreflex function; b) carotid baroreflex function; c) cardiopulmonary baroreflex function; and d) the degree of interaction between the cardiopulmonary and carotid baroreflexes.

Sixteen males and sixteen females were recruited for this study; eight of each gender were aerobically trained athletes; the remaining eight were untrained control subjects. Each subject performed a maximal exercise stress test for aerobic capacity (VO2max). On a separate day the blood volume and the cardiovascular responses to progressive (0 to -50 torr) lower body negative pressure (LBNP) were determined. The female subjects were observed to be significantly more tolerant of the LBNP than the male subjects. No differences between groups were observed in changes in leg volume, cardiac index, blood pressure, or heart rate during LBNP. However, the females, in comparison to the males, maintained stroke index at a higher level, and increased regional vasoconstriction more, during the LBNP induced hypotensive stress. These findings suggest that female subjects withstand LBNP to -50 torr better than male subjects.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of Witwatersrand in fulfilment of the requirements for the degree of Master of Science in Engineering. 2017 / The baroreceptor is a stretch receptor which detects changes in pressure in arterial blood vessels. Baroreceptor nerves inform the brainstem of changes in blood pressure, which then influences sympathetic and parasympathetic nervous activity to counteract that change. Due to the relationship between essential hypertension, sympathetic nervous activity and the baroreflex, there is some debate in the literature about whether the baroreflex can act as a long-term controller of blood pressure. This debate has increased in recent years, due to the high prevalence of essential hypertension in all societies and the introduction of new technologies to counteract drug-resistance hypertension. The baroreflex has become a source of debate due to the complex physiological feedback control that regulates blood pressure and due to new stimulating electrical devices, which have shown promising results in reducing drug-resistant essential hypertension. system. This is done through a literature survey extending through experimental and modelling research, where selected mathematical models of the baroreceptor are then analysed and simulated to find the best performing model, so that they may be simulated for an extended frequency response than what would be experimentally possible. The purpose of this investigation is to determine, through simulation, what the sensor static and dynamic characteristics are. Through this characterisation of the sensor behaviour of the baroreceptor in the baroreflex control loop, it is then possible to infer whether the baroreflex can act as a long-term controller of blood pressure. An overview of experimental and analytical investigations on the baroreceptor over the last 70 years is summarised. This overview includes mathematical models, which predict experimental results. A subset of four models from Srinivasen et al., Bugenhagen et al., Beard et al. and Mahdi et al. are selected. These models are implemented in MATLAB and Simulink. The parameters and experimental conditions are integrated into the Simulink models, and the simulated results are compared to the reported experimental data. In this way, each mathematical model is evaluated using secondary data for its ability to simulate the expected behaviour. Thereafter, all simulated models are compared under the same input conditions (a 0-230 mmHg step input over 12 s). These results are used to select the best performing models, based on how well they were parameterised and validated for experimental tests. The best performing models are those of Beard et al. and Bugenhagen et al. They are tested for a wide range of artificial inputs at different frequencies, with sinusoidal inputs which have periods that range from 0.1 s to 10 days and have a 100 mmHg operating point with a 1 mmHg peak amplitude. All modelling techniques studied show that the baroreceptor firing response resets due to the rate of change in strain in the visco-elastic arterial wall. Both tested model frequency responses, although parameterised for different species and for different major vessels, show high sensitivity to inputs in range from 1 s to 1 min 36 s (0.01 Hz 1Hz), and very low sensitivity for changes that are longer than 16 min 36s (0.001 Hz). This extrapolated simulation suggests a zero gain near DC. The simulated frequency response of the best performing baroreceptor models, which were validated against short-term experimental data, indicate that the baroreceptor is only able to sense changes that happen in less than 1 min 16s. The critical analysis of all the simulated baroreceptor models show that this characteristic of the baroreceptor is caused by the visco-elastic layers of the arterial wall, and is likely in all baroreceptors regardless of type or species. It also indicates that under electrical stimulation of the baroreceptor, the input signal from the electrical device bypasses the baroreceptor nerve ending (which is embedded in the arterial wall) and that the electrical signal of the baroreceptor is bypassed by the new stimulated electrical signal of the device. Furthermore, if the sensor can only detect short-term changes, then it is unlikely that the baroreceptor can inform the brainstem on longterm changes to mean arterial blood pressure. Therefore, based on the models examined in this study, this suggests that the baroreceptor is unlikely to be involved in long-term blood pressure control. This analysis of the best performing model is presented to show the limitations of the baroreflex in long term control of blood pressure. It serves as a simulated experiment to rationalise the contentious debate around the role of the baroreflex in long term blood pressure control, and to allow for future improvements that can be made on the baroreceptor model to allow for more extended modelling on sor characteristics. An improvement that could be applied to the best performing baroreceptor models, implemented in this study, is to examine the effects of ageing and inter-species variability on carotid sinus dimensions and visco-elastic wall properties. / CK2018

Aortic baroreflex (ABR) control of blood pressure was examined in 7 untrained (UT) and 8 endurance exercise trained (EET) young men. ABR control of blood pressure was determined during a steady state phenylephrine infusion to increase mean arterial pressure 10-15 mmHg, combined with positive neck pressure to counteract the increased carotid sinus transmural pressure, and low levels of lower body negative pressure to counteract the increased central venous pressure. Functioning alone, the ABR was functionally adequate to control blood pressure. However, ABR control of HR was significantly diminished in the EET subjects due solely to the decrease in the ABR sensitivity. The persistent strain from an increased stroke volume resulting from endurance exercise training could be the responsible mechanism.

壓力感受器在調節血壓的壓力感受性反射中的作用已是眾所周知。兩個動脈壓力感受器，分別為主動脈壓力感受器和頸動脈壓力感受器。它們作為重要的感應器以檢測主要動脈血壓，並和孤束核溝通，從而調節血壓。然而，壓力感受器的機械力敏感元件的分子身份仍是奧秘。因為機械敏感的陽離子通道受機械力刺激時會增加的神經元活動, 所以機械敏感的陽離子通道是合適的候選人。 / 在本研究中，通過使用膜片鉗和動作電位的測量，瞬时受体电位通道C5(TRPC5)被確定在主動脈壓力感受器的機械傳感器中。透過在壓力感受器神經元的鈣測量實驗，證實TRPC5參與由拉伸引起的鈣離子([Ca²⁺]i)上升。TRPC5基因敲除小鼠出現壓力感受器功能受損, 表明了TRPC5在血壓控制的重要性。 / 比較主動脈壓力感受器或頸動脈壓力感受器的不同敏感度現時存有不少爭論。在本研究中，我發現主動脈壓力感受器比頸動脈壓力感受器對於壓力變化更加敏感。此外，我還發現了主動脈壓力感受器神經元比頸動脈壓力感受器神經元有一個相對較高的瞬时受体电位通道V4(TRPV4)表達。鈣測量研究表明TRPV4通道在主動脈壓力感受器神經元的靈敏度可能發揮著重要作用。 / Baroreceptors have been well known for its role in the baroreflex regulation of blood pressure. Two arterial baroreceptors, aortic and carotid baroreceptors, serve as the important sensors to detect blood pressure in main arteries, and they communicate with the solitary nucleus tract for blood pressure regulation. However, the molecular identity of the mechano-sensitive components in the baroreceptors is still mysteries. Mechano-sensitive cation channels are the fascinating candidates as they increase neuronal activities when stimulated by stretch. In the present study, with the use of patch clamp and action potential measurement, TRPC5 channels were identified to be the mechanical sensor in the aortic baroreceptor. Calcium measurement studies demonstrated that TRPC5 was involved in the stretch-induced [Ca2+]i rise in baroreceptor neurons. The importance of TRPC5 in blood pressure control was also studied in TRPC5 knockout mice, which displayed an impaired baroreceptor function. / There have been controversies as to whether aortic baroreceptors or carotid baroreceptors are more sensitive to the change in blood pressure. In the present study, aortic baroreceptor was found to be more sensitive to the pressure change than the carotid baroreceptor. Furthermore, I also found a relative higher expression of TRPV4, a mechanosensitive channel, in the aortic baroreceptor neurons than in the carotid baroreceptor neurons. Moreover, calcium measurement studies showed that TRPV4 channels should play an important role in governing the differential pressure sensitivity in these two types of baroreceptor neurons. / Taken together, the present study provided novel information on the role of TRPC5 and TRPV4 in baroreceptor mechanosensing. In future, it will be of interest to explore whether TRPC5 and/or TRPV4 dysfunction could contribute to human diseases that are related to blood pressure control. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lau, On Chai Eva. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 133-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Declaration --- p.i / Abstract of the thesis entitled --- p.ii / Acknowledgement --- p.vii / Abbreviation --- p.ix / Table of content --- p.xii / List of figures --- p.xv / List of table --- p.xvii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Baroreceptors --- p.1 / Chapter 1.1.2 --- Arterial baroreceptors --- p.2 / Chapter 1.1.2.1 --- Functions of arterial baroreceptors --- p.4 / Chapter 1.1.2.2 --- Sensitivity of the arterial baroreceptors --- p.6 / Chapter 1.1.3 --- Other baroreceptors --- p.8 / Chapter 1.1.4 --- The molecular identity of the mechanosensors in baroreceptor neurons --- p.9 / Chapter 1.2 --- Transient receptor potential ion channels (TRP channels) --- p.10 / Chapter 1.2.1 --- TRP channels superfamily --- p.10 / Chapter 1.2.2 --- Multimerization of TRP channels --- p.12 / Chapter 1.2.3 --- Physiological functions --- p.14 / Chapter 1.2.4 --- Mechanosensitive TRP channels --- p.16 / Chapter 1.2.5 --- Canonical transient receptor potential 5 (TRPC5) channels --- p.17 / Chapter 1.2.6 --- Vanilloid transient receptor potential 4 (TRPV4) channels Figures --- p.20 / Chapter Chapter 2: --- Objectives --- p.34 / Chapter Chapter 3: --- Materials and Methods --- p.35 / Chapter 3.1 --- Materials --- p.35 / Chapter 3.1.1 --- Chemicals and reagents --- p.35 / Chapter 3.1.2 --- Solutions --- p.36 / Chapter 3.1.2.1 --- Solutions for calcium imaging --- p.36 / Chapter 3.1.2.2 --- Solutions for electrophysiology study --- p.38 / Chapter 3.1.2.3 --- Solutions for agarose gel electrophoresis --- p.41 / Chapter 3.1.3 --- Primers for RT-PCR --- p.42 / Chapter 3.1.4 --- Animals --- p.43 / Chapter 3.2 --- Methods --- p.43 / Chapter 3.2.1 --- Total RNA isolation and RT-PCR --- p.43 / Chapter 3.2.2 --- Immunohistochemistry --- p.44 / Chapter 3.2.3 --- Neuron labeling by DiI --- p.45 / Chapter 3.2.4 --- Neuron culture --- p.46 / Chapter 3.2.5 --- [Ca²⁺]i measurement --- p.47 / Chapter 3.2.6 --- Electrophysiology --- p.48 / Chapter 3.2.7 --- Evaluation of baroreflex response --- p.49 / Chapter 3.2.8 --- Telemetric measurement of blood pressure --- p.50 / Chapter 3.2.9 --- Statistical analysis --- p.51 / Figures --- p.52 / Chapter Chapter 4: --- Functional role of TRPC5 channels in aortic baroreceptor --- p.56 / Chapter 4.1 --- Introduction --- p.56 / Chapter 4.2 --- Materials and Methods --- p.59 / Chapter 4.2.1 --- Animals --- p.59 / Chapter 4.2.2 --- Immunohistochemistry --- p.59 / Chapter 4.2.3 --- Neuron labeling by DiI --- p.61 / Chapter 4.2.4 --- Neuron culture --- p.62 / Chapter 4.2.5 --- [Ca²⁺]i measurement --- p.63 / Chapter 4.2.6 --- Electrophysiology --- p.63 / Chapter 4.2.7 --- Evaluation of baroreflex response --- p.64 / Chapter 4.2.8 --- Telemetric measurement of blood pressure --- p.66 / Chapter 4.2.9 --- Statistical analysis --- p.67 / Chapter 4.3 --- Results --- p.67 / Chapter 4.3.1 --- Endogenous expression of TRPC5 channels in aortic baroreceptor neurons --- p.67 / Chapter 4.3.2 --- Characterization on the pressure-sensitive component in aortic baroreceptors --- p.68 / Chapter 4.3.3 --- Involvement of TRPC5 in [Ca²⁺]i response in aortic baroreceptor neurons --- p.69 / Chapter 4.3.4 --- Participation of TRPC5 in pressure-induced action potential firing in cultured aortic baroreceptor neurons --- p.70 / Chapter 4.3.5 --- Role of TRPC5 in baroreceptor sensory nerve activity and baroreflex regulation --- p.71 / Chapter 4.3.6 --- Importance of TRPC5 in baroreceptor function --- p.72 / Chapter 4.4 --- Discussions --- p.74 / Figures --- p.79 / Table --- p.98 / Chapter Chapter --- 5: TRPV4 channels and baroreceptor sensitivity --- p.99 / Chapter 5.1 --- Introduction --- p.99 / Chapter 5.2 --- Materials and Methods --- p.101 / Chapter 5.2.1 --- Animals --- p.101 / Chapter 5.2.2 --- Neuron labeling by DiI --- p.101 / Chapter 5.2.3 --- Neuron culture --- p.102 / Chapter 5.2.4 --- Electrophysiology --- p.103 / Chapter 5.2.5 --- Immunohistochemistry --- p.104 / Chapter 5.2.6 --- [Ca²⁺]i measurement --- p.105 / Chapter 5.2.7 --- Statistical analysis --- p.105 / Chapter 5.3 --- Results --- p.106 / Chapter 5.3.1 --- Properties of the aortic and carotid baroreceptor neurons --- p.106 / Chapter 5.3.2 --- Stretch sensitivity of aortic and carotid baroreceptor neurons --- p.108 / Chapter 5.3.3 --- mRNA expression of mechanosensitive TRP channels in aortic and carotid baroreceptor neurons --- p.109 / Chapter 5.3.4 --- Protein expression of TRPV4 channels in aortic and carotid baroreceptor neurons --- p.109 / Chapter 5.3.5 --- Involvement of TRPV4 in stretch-induced [Ca²⁺]i response in baroreceptor neurons --- p.110 / Chapter 5.4 --- Discussions --- p.111 / Figures --- p.116 / Chapter Chapter 6: --- General conclusions and future directions --- p.124 / Figures --- p.128 / References --- p.133

Wong Kwok-Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 89-107). / Abstracts in English and Chinese. / Title --- p.i / Abstract (English) --- p.ii / Abstract (Chinese) --- p.v / Content --- p.vii / Acknowledgement --- p.x / Abbreviation --- p.xii / Lists of tables and figures --- p.xiii / Chapter Chapter 1 --- General introduction --- p.1 / Chapter Chapter 2 --- "Effects of salinity on the cardiovascular responses and dipsogenic behaviors and silver seabream, Sparus sarba." / Chapter 2.1 --- Literature review / Chapter 2.1.1 --- Teleost euryhalinity --- p.5 / Chapter 2.1.2 --- Salinity and blood respiratory properties --- p.7 / Chapter 2.1.3 --- Salinity and blood volume --- p.8 / Chapter 2.1.4 --- Salinity and blood pressure --- p.10 / Chapter 2.1.5 --- Intestine physiology --- p.12 / Chapter 2.1.6 --- Summary --- p.14 / Chapter 2.2 --- Materials and methods / Chapter 2.2.1 --- Experimental animals --- p.19 / Chapter 2.2.2 --- Salinity adaptation --- p.19 / Chapter 2.2.3 --- Drinking rate measurement --- p.19 / Chapter 2.2.4 --- Respiratory characteristics --- p.20 / Chapter 2.2.5 --- Blood volume measurement --- p.21 / Chapter 2.2.6 --- Blood pressure experiment --- p.23 / Chapter 2.2.7 --- Statistical analysis --- p.23 / Chapter 2.3 --- Results / Chapter 2.3.1 --- Drinking rate --- p.25 / Chapter 2.3.2 --- Oxygen dissociation curves --- p.27 / Chapter 2.3.3 --- Blood volume --- p.29 / Chapter 2.3.4 --- Blood pressure --- p.31 / Chapter 2.4 --- Discussion / Chapter 2.4.1 --- Drinking rate --- p.36 / Chapter 2.4.2 --- Oxygen dissociation curves --- p.37 / Chapter 2.4.3 --- Blood volume --- p.38 / Chapter 2.4.4 --- Blood pressure --- p.40 / Chapter Chapter 3 --- "Manipulation of renin-angiotensin system in relation to the cardiovascular responses and dipsogenic behaviors of silver seabream, Sparus sarba." / Chapter 3.1 --- Literature review / Chapter 3.1.1 --- Renin angiotensin system (RAS) --- p.41 / Chapter 3.1.2 --- RAS and blood pressure --- p.47 / Chapter 3.1.3 --- RAS and drinking --- p.53 / Chapter 3.1.4 --- RAS and Cortisol --- p.55 / Chapter 3.1.5 --- RAS and kidney --- p.58 / Chapter 3.1.6 --- Summary --- p.58 / Chapter 3.2 --- Materials and methods / Chapter 3.2.1 --- Experimental animals --- p.61 / Chapter 3.2.2 --- Salinity adaptation --- p.61 / Chapter 3.2.3 --- Drinking rate measurement --- p.61 / Chapter 3.2.4 --- Determination of angiotensin converting enzyme (ACE) activity --- p.61 / Chapter 3.2.5 --- Blood pressure experiment --- p.62 / Chapter 3.2.6 --- Statistical analysis --- p.63 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Drinking rate --- p.64 / Chapter 3.3.2 --- ACE activity --- p.69 / Chapter 3.3.3 --- Blood pressure --- p.71 / Chapter 3.4 --- Discussion / Chapter 3.4.1 --- Drinking rate --- p.77 / Chapter 3.4.2 --- ACE activity --- p.81 / Chapter 3.4.3 --- Blood pressure --- p.83 / Chapter Chapter 4 --- General conclusion --- p.86 / Reference --- p.89

This study evaluated the efficacy of cognitive therapy and biofeedback training in lowering Dlood pressures of normotensives under no-stress and stress conditions. A cognitive therapy group was compared to biofeedback and habituation control groups with 32 normotensives. Subjects were taught to use the electronic sphygmomanometer that served as the device to measure blood pressure during pretreatment and posttreatment phases of the study. These measurement phases each consisted of three 19 minute periods. Trie first period consisted of no-stress, and then a stress period followed. Return-to-no-stress was the final period. Subjects in the cognitive therapy and biofeedbacK groups received five sessions of self-control training of 66 minutes each between the pre- and posttreatment phases. The cold pressor was the analogue stressor used to induce bxood pressure elevations,

Cardiovascular responses and tolerance to an orthostatic stress were examined in eight men before and after eight months of endurance exercise training. Following training, maximal oxygen consumption and blood volume were increased, and resting heart rate reduced. Orthostatic tolerance was reduced following training in all eight subjects. It was concluded that prolonged endurance training decreased orthostatic tolerance and this decrease in tolerance appeared associated with attenuated baroreflex sensitivity and alterations in autonomic balance secondary to an increased parasympathetic tone noted with training.