Cardiovascular Regulatory Mechanisms Research Articles

Effects of training load on heart rate variability and blood pressure in track and field athletes and skiers

BACKGROUND: Adaptation of human body to the harsh conditions of the European North remains a topic of ongoing interest, despite numerous studies on the subject. There is a need to study population groups whose daily activities involve physical activity in extreme northern conditions. One such group includes athletes who participate in endurance sports. For athletes engaged in cyclical sports, competitive activities becomes can be particularly demanding, requiring sustained physical exertion and maximum power generation. Training and competing in harsh conditions place significant strain on the body’s cardiovascular regulation mechanisms. Over time, this may result in detrimental structural and biochemical changes in the cardiovascular system. AIM: To identify the patterns of changes in heart rate regulation among track and field athletes and skiers after a training load. MATERIAL AND METHODS: Athletes from the Arkhangelsk region, including skiers and track and field athletes in the mass sports categories, who regularly compete in regional events, took part in the study. The studies took place in the medical offices of sports complexes, where the UPFT-1/30“Psychophysiologist” device was used to record and analyze cardiointervalograms. Blood pressure was recorded before and after training sessions using the Criticare System 8100H monitor. RESULTS: The initial variational span (VR) values of the duration of cardio intervals before exercise were slightly lower than the reference values in both the group of skiers and the group of athletes. At the same time, the mean square deviation (SD) values initially fell within normal range. Following the training load, both groups experienced a statistically significant decrease in SD and VR values, falling below the lower limit of the permissible range. Furthermore, spectral analysis of the cardiac intervals before exercise indicated a high level of neurohumoral regulation. After exercise, there was a statistically significant decrease in the initial values of TP in both groups, aligning with the average level of neurohumoral regulation. CONCLUSION: The results obtained in track and field athletes with a predominant anaerobic training load and skiers with a predominant aerobic load suggest that the training load of a predominantly aerobic nature may lead to less pronounced stress on the regulatory systems. This hypothesis was further supported by the results of the changes in blood pressure.

Anxiety symptom severity is associated with increased arterial blood pressure and arterial blood pressure variability in apparently healthy young adults

Introduction: Lifetime prevalence of anxiety disorders is approximately 30%, and anxiety is associated with an increased susceptibility to develop cardiovascular disease. Anxiety disorders have been linked to hypertension, and autonomic dysfunction has been posited as a contributing factor. However, anxiety symptom severity exists on a continuum, and it is less clear how anxiety severity is associated with blood pressure or beat-to-beat blood pressure variability, a hemodynamic biomarker that reflects dynamic cardiovascular regulatory mechanisms. The objective of this study was to test the hypothesis that self-reported anxiety symptom severity is positively associated with resting blood pressure and beat-to-beat blood pressure variability among healthy young adults without cardiometabolic disease. Methods: Resting beat-to-beat blood pressure (mmHg; finger plethysmography) and anxiety scores from a self-report anxiety symptom questionnaire (Zung Self-Rated Anxiety Scale, ZSRA) were collected in 53 healthy young adults (40 males, 13 females, age = 25 ± 4 yr, BMI = 25 ± 6 kg/m2). Following 10 minutes of quiet rest, signals were recorded over a 10-minute period with participants in a supine position, and the middle 8 minutes were used for analyses. Multiple linear regression was used to examine the independent relations of ZSRA with systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), SAP standard deviation (SAPSD), DAP standard deviation (DAPSD), and MAP standard deviation (MAPSD) while controlling for age and sex. To further understand whether the observed relations between ZSRA and beat-to-beat blood pressure variability were explained by or independent of elevated absolute arterial pressure, partial correlations (rxy,z) were performed for ZSRA versus SAPSD, DAPSD, and MAPSD while partialling out the effect of SAP, DAP, and MAP, respectively. Results: ZSRA was significantly correlated with SAP (β = 0.34, p = 0.015), MAP (β = 0.32, p = 0.023), SAPSD (β = 0.36, p = 0.008), DAPSD (β = 0.35, p = 0.014), and MAPSD (β = 0.37, p = 0.008). When controlling for SAP, DAP, and MAP, ZSRA was independently associated with SAPSD (rxy,z = 0.34, p = 0.016), DAPSD (rxy,z = 0.35, p = 0.012), and MAPSD (rxy,z = 0.40, p = 0.005). Conclusion: Self-reported anxiety symptom severity is associated with increased blood pressure and beat-to-beat blood pressure variability, which indicates an important relationship between anxiety and blood pressure regulation across a continuum of symptom severity. This study is the first to show a relationship between anxiety and beat-to-beat blood pressure variability, independent of absolute mean blood pressure, among healthy young adults devoid of cardiometabolic disease. Our data build upon and align with previous findings that anxiety symptom severity is associated with increased muscle sympathetic nerve activity among healthy young adults and enhances our understanding of the relationship between anxiety and cardiovascular health, even among apparently healthy individuals. Funding provided by a grant from the Injury Prevention Research Center through the CDC (R49 CE003095; NDMJ). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Evaluation of the translation of multiple cardiovascular regulatory mechanisms in the anesthetized dog

The strategic and targeted use of an anesthetized canine cardiovascular model early in drug discovery enables a comprehensive cardiovascular and electrophysiological assessment of potential safety liabilities and guides compound selection prior to initiation of chronic toxicological studies. An ideal model would enable exposure-response relationships to guide safety margin calculations, have a low threshold to initiate, and have quick delivery of decision quality data. We have aimed to profile compounds with diverse mechanism of actions (MoAs) of “non-QT” cardiovascular drug effects and evaluate the ability of nonclinical in vivo cardiovascular models to detect clinically reported effects. The hemodynamic effects of 11 drugs (atropine, itraconazole, atenolol, ivabradine, milrinone, enalaprilat, fasudil, amlodipine, prazosin, amiloride, and hydrochlorothiazide) were profiled in an anesthetized dog cardiovascular model. Derived parameters included: heart rate, an index of left ventricular contractility, mean arterial pressure, systemic vascular resistance, and cardiac output. Species specific plasma protein data was generated (human, dog) and utilized to calculate free drug concentrations. Using the anesthetized dog cardiovascular model, 10 of the 11 drugs displayed the predicted changes in CV parameters based on their primary MoAs and corresponding clinically described effects. Interestingly but not unexpected, 1 of 11 failed to display their predicted CV pattern which is likely due to a delay in pharmacodynamic effect that is beyond the duration of the experimental model (hydrochlorothiazide). The analysis from the current study supports the strategic use of the anesthetized dog model early in the drug discovery process for a comprehensive cardiovascular evaluation with good translation to human.

Econometric predictive model for assessing the functional state of students during the examination period: a cross-sectional exploratory pilot study

Background. Mathematical modeling is widely used in medicine to analyze the body systems in terms of their structure, work and interrelations. The present study investigates factors associated with the adaptation potential of the cardiovascular system, develops multiple regression models for the dependence of the adaptive potential on these factors, and compares the significance of the linear model with non-linear ones. Objectives. To determine changes in the circulatory system in students during the examination period and develop a mathematical model for predicting the adaptive potential of the cardiovascular system. Methods. The cohort observational study enrolled 74 students of Kirov State Medical University, aged 18–23 years, who gave consent to the survey. The participants were divided into two cohorts depending on the dominant type of the autonomic nervous system (group 1 — individuals with the dominance of sympathetic part of the peripheral division of the autonomic nervous system (n = 54) and group 2 — individuals with vagotonic type of regulation (n = 20)). The relationship between the hemodynamic parameters and the initial autonomic tone was considered as the main relevancy criterion of the study. Comparative analysis of hemodynamic parameters depending on the dominant type of autonomic nervous system was carried out in the cohorts. Development of the regression model was based on 74 observations. Data description included median (Me) and interquartile range representing 25th and 75th percentiles. The indicators in independent samples (cohorts) were compared using the non-parametric Mann—Whitney U test. Correlation analysis of relationships between the studied variables involved Spearman’s criterion (r). Differences and correlations were considered significant at p = 0.05. Calculations and analyses were performed using spreadsheets in Statistica Advanced 10 for Windows RU (Statsoft, Russia). Results. The state of the cardiovascular system significantly depends on the dominant type of the autonomic nervous system. Such parameters as stroke volume, cardiac index, cardiac minute output, circulatory efficiency were established to be significantly higher, whereas diastolic blood pressure, mean arterial pressure, cardiovascular index — lower in individuals with activation of the sympathetic part of the autonomic division of the peripheral nervous system. The study revealed significant correlations between the parameters of central hemodynamic and anthropometric parameters depending on the dominant type of the autonomic nervous system. Conclusion. Significant differences of hemodynamic parameters depending on the dominant type of autonomic system indicate the relevance of neurohumoral mechanisms of cardiovascular regulation. The values in adaptive potential exceeded 2.0 points, indicating the stress of the cardiovascular adaptation. The correlation regression analysis showed the greatest significance of the multiple linear regression model developed by the authors for predicting the adaptive potential of the cardiovascular system.

Heart Rate Variability Parameters to Evaluate Autonomic Functions in Healthy Young Subjects during Short-Term “Dry” Immersion

There is a gap in the current knowledge on the immediate mechanisms of cardiovascular regulation in human subjects within short-term exposure to modeled microgravity using “dry” immersion. Aim. The purpose of the study was to evaluate cardiovascular responses in young healthy subjects during a 45 min session with the help of linear and nonlinear heart rate variability and hemodynamics parameters. The research voluntarily enrolled 33 subjects (18 men, 15 women) aged 19–23 years old. Results. The study showed that systolic and diastolic blood pressure was quite stable, some time-domain parameters of heart rate variability (SDNN, RMSSD, pNN50, etc.) and the frequency-domain (TP, HF, LF, but not VLF) have significantly increased within a 45 min “dry” immersion session. Of the non-linear parameters of heart rate variability, only ApEn significantly decreased during the “dry” immersion session. Conclusion. Our results suggest that a short-term 45 min DI session provokes in young healthy subjects neurogenic autonomic reaction based on the baroreceptor reflex. This provides stable hemodynamics in these subjects along the “dry” immersion session.

Blood pressure variability: methodological aspects, clinical relevance and practical indications for management - a European Society of Hypertension position paper ∗.

Blood pressure is not a static parameter, but rather undergoes continuous fluctuations over time, as a result of the interaction between environmental and behavioural factors on one side and intrinsic cardiovascular regulatory mechanisms on the other side. Increased blood pressure variability (BPV) may indicate an impaired cardiovascular regulation and may represent a cardiovascular risk factor itself, having been associated with increased all-cause and cardiovascular mortality, stroke, coronary artery disease, heart failure, end-stage renal disease, and dementia incidence. Nonetheless, BPV was considered only a research issue in previous hypertension management guidelines, because the available evidence on its clinical relevance presents several gaps and is based on heterogeneous studies with limited standardization of methods for BPV assessment. The aim of this position paper, with contributions from members of the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular Variability and from a number of international experts, is to summarize the available evidence in the field of BPV assessment methodology and clinical applications and to provide practical indications on how to measure and interpret BPV in research and clinical settings based on currently available data. Pending issues and clinical and methodological recommendations supported by available evidence are also reported. The information provided by this paper should contribute to a better standardization of future studies on BPV, but should also provide clinicians with some indications on how BPV can be managed based on currently available data.

Modern aspects of short-term blood presssure variability in arterial hypertension

Abstract. Arterial hypertension is an important public health problem worldwide due to its high incidence and associated risks of cardiovascular and renal diseases such as coronary heart disease, cerebrovascular disease, chronic kidney disease. The level of blood pressure is the main indicator of hypertension treatment effectiveness and leading cardiovascular risk factor. Blood pressure is one of the most dynamic physiological parameters, which is characterized by continuous and significant changes beat-to-beat, over 24 h, day-to-day, and visit-to-visit. Under physiological conditions, these blood pressure variations are mostly represent a response to environmental stimulation aimed at maintaining cardiovascular homeostasis. However, a persistent increase in the blood pressure variability may be the result of pathological changes in the mechanisms of cardiovascular regulation, which leads to alterations in cardiovascular system functioning with the subsequent development of cardiovascular diseases and complications. The phenomenon of blood pressure variability has been known for a long time. It was first described by the English physiologist Stephen Gales in 1733, and its assessment in clinical conditions became possible at the end of the 19th – beginning of the 20th century, after the invention of the sphygmomanometer and the introduction of non-invasive blood pressure measurement using the Riva-Rocci and Korotkov methods. Historically, blood pressure variability has been viewed as a random factor caused by measurement error, which prevents accurate blood pressure measurement. Вlood pressure variability was considered the so-called «background noise», which was not given any importance and tried to overcome with the help of improving monitoring. However, already at the end of the last century, the discussion of the clinical significance of this indicator in patients with hypertension began. The clinical significance and prognostic implications of blood pressure variability have been demonstrated by a series of clinical and population-based studies conducted in recent years, in which elevated blood pressure variability was associated with a higher risk of target organ damage, cardiovascular events, cardiovascular and total mortality independently of blood pressure level. The review presents modern concepts of blood pressure variability, its classification, and assessment methods. The pathogenetic significance of short-term BP variability in patients with arterial hypertension is reviewed, with a discussion of the available evidence regarding the significance of short-term blood pressure variability in cardiovascular risk stratification.

Correlation between Angiotensin Serum Levels and Very-Low-Frequency Spectral Power of Heart Rate Variability during Hemodialysis.

Cardiovascular regulatory mechanisms that fail to compensate for ultrafiltration and cause hypovolemia during hemodialysis (HD) are not completely understood. This includes the interaction between the autonomic nervous system and the biochemistry that regulates blood pressure and modulates cardiac activity and vascular tone in response to hypovolemia in patients treated with HD. The objective was to evaluate the association of spectral indices of heart rate variability (HRV) with serum levels of angiotensin II, angiotensin 1–7, nitric oxide and total antioxidant capacity during HD. Electrocardiographic records were obtained from 20 patients during HD (3 h), from which HRV data and spectral power data in the very-low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands were generated. Three blood samples per patient were collected during HD (0.0, 1.5, 3.0 h) to determine the levels of biomarkers involved in the pressor response during HD. Angiotensin II had a positive correlation with VLF (r = 0.390) and with LF/HF (r = 0.359) and a negative correlation with LF (r = −0.262) and HF (r = −0.383). There were no significant correlations between HRV and the other biomarkers. These results suggest that during HD, VLF could reflect the serum levels of angiotensin II, which may be associated with the autonomic response to HD.

Implication of the Central Nucleus of the Amygdala in Cardiovascular Regulation and Limiting Maximum Exercise Performance During High-intensity Exercise in Rats

To date, the mechanism of central fatigue during high-intensity exercise has remained unclear. Here we elucidate the central mechanisms of cardiovascular regulation during high-intensity exercise with a focus on the hypothesis that amygdala activation acts to limit maximum exercise performance. In the first of three experiments, we probed the involvement of the central nucleus of the amygdala (CeA) in such regulation. Wistar rats were subjected to a maximum exercise test and their total running time and cardiovascular responses were compared before and after bilateral CeA lesions. Next, probing the role of central pathways, we tested whether high-intensity exercise activated neurons in CeA and/or the hypothalamic paraventricular nucleus (PVN) that project to the nucleus tractus solitarius (NTS). Finally, to understand the potential autonomic mechanisms affecting maximum exercise performance, we measured the cardiovascular responses in anesthetized rats to electrical microstimulation of the CeA, PVN, or both. We have found that (1) CeA lesions resulted in an increase in the total exercise time and the time at which an abrupt increase in arterial pressure appeared, indicating an apparent suppression of fatigue. (2) We confirmed that high-intensity exercise activated both the PVN-NTS and CeA-NTS pathways. Moreover, we discovered that (3) while stimulation of the CeA or PVN alone both induced pressor responses, their simultaneous stimulation also increased muscle vascular resistance. These results are evidence that cardiovascular responses during high-intensity exercise are affected by CeA activation, which acts to limit maximum exercise performance, and may implicate autonomic control modulating the PVN-NTS pathway via the CeA.

Prenatal Hypoxia Affects Foetal Cardiovascular Regulatory Mechanisms in a Sex- and Circadian-Dependent Manner: A Review.

Prenatal hypoxia during the prenatal period can interfere with the developmental trajectory and lead to developing hypertension in adulthood. Prenatal hypoxia is often associated with intrauterine growth restriction that interferes with metabolism and can lead to multilevel changes. Therefore, we analysed the effects of prenatal hypoxia predominantly not associated with intrauterine growth restriction using publications up to September 2021. We focused on: (1) The response of cardiovascular regulatory mechanisms, such as the chemoreflex, adenosine, nitric oxide, and angiotensin II on prenatal hypoxia. (2) The role of the placenta in causing and attenuating the effects of hypoxia. (3) Environmental conditions and the mother’s health contribution to the development of prenatal hypoxia. (4) The sex-dependent effects of prenatal hypoxia on cardiovascular regulatory mechanisms and the connection between hypoxia-inducible factors and circadian variability. We identified that the possible relationship between the effects of prenatal hypoxia on the cardiovascular regulatory mechanism may vary depending on circadian variability and phase of the days. In summary, even short-term prenatal hypoxia significantly affects cardiovascular regulatory mechanisms and programs hypertension in adulthood, while prenatal programming effects are not only dependent on the critical period, and sensitivity can change within circadian oscillations.

Long-Term Visit-To-Visit Blood Pressure Variability and Cognition: A Systematic Review of Observational Studies

Existing literature suggests that in comparison to a single blood pressure (BP) measurement, or the mean of multiple recordings, BP variability (BPV) may reflect dysfunction in cardiovascular regulatory mechanisms, leading to compromised cognitive health. No systematic review has yet synthesized observational reports examining the association between cognition and long-term visit-to-visit BPV. In response, a comprehensive literature search was executed in December, 2019, and updated in December, 2020. Methodological approach was pre-registered (https://osf.io/vmnuq/). Of 1385 reports, 27 met eligibility criteria. Most executed secondary analyses using existing longitudinal datasets of older adults (N=21). Intervals between measurement occasions ranged from 30 days to four years, and follow-up ranged from 0.5-25 years. Most studies computed more than one index of BPV (range=1-6), and all included at least three BP recordings (range=3-12). Given extensive between-study variability in analytic approach (e.g., BPV and cognition treated as continuous and/or categorical variables; number of covariates ranged 0-18), our team determined that meta-analyzing the results would be inappropriate. Despite heterogeneity in study characteristics, the majority (85.2%) reported that systolic BPV (sBPV) was negatively associated with cognition; specifically, higher sBPV was associated with cognitive impairment (N=9), cognitive decline (N=6), and/or risk of dementia (N=5). Four studies also revealed higher sBPV in individuals with dementia compared to controls. Three studies reported no association, while one reported a positive significant association between BPV and cognition. Results were similar for diastolic BPV. Despite considerable heterogeneity in study characteristics, greater variability in visit-to-visit BP appears to be consistently associated with adverse cognitive outcomes.

Neuroinflammation and Microglial Activation at Rostral Ventrolateral Medulla Underpin Cadmium-Induced Cardiovascular Dysregulation in Rats.

PurposeCadmium is a heavy metal and environmental toxicant known to act on the central cardiovascular regulatory mechanisms, and one of its brain targets is the rostral ventrolateral medulla (RVLM), a brainstem site that maintains blood pressure and sympathetic vasomotor tone. The present study assessed the hypothesis that cadmium elicits cardiovascular dysregulation by inducing neuroinflammation and microglial activation, two potential cellular mechanisms, in RVLM.MethodsAdult male Sprague–Dawley rats were used for measuring cardiovascular responses after intravenous administration of cadmium. We further conducted real-time PCR, immunofluorescence staining, in situ determination of mitochondrial superoxide, hematoxylin and eosin staining, and enzyme-linked immunosorbent assay (ELISA) to identify cytokine and chemokine mRNA expression, microglia activation, superoxide production, and necrotic and apoptotic cell death in RVLM.ResultsWe found animals maintained under propofol anesthesia, intravenous administration of cadmium acetate (4 mg/kg) resulted in an increase, followed by a rebound and a secondary decrease in spontaneous baroreflex-mediated sympathetic vasomotor tone, a progressive reduction in mean arterial pressure and heart rate, alongside augmentation of pro-inflammatory cytokine and chemokine in RVLM. All those cardiovascular and neuroinflammatory events were reversed by pretreatment with an anti-inflammatory drug, pentoxifylline (50 mg/kg, i.p.). There were also concurrent microglial activation, reactive oxygen species production, hypoxia, reduced blood flow, and necrotic and apoptotic cell death in RVLM.ConclusionBased on these biochemical, pharmacological and morphological observations, we conclude that neuroinflammation and microglial activation at RVLM, and their downstream cellular mechanisms, causally underpin cadmium-induced cardiovascular dysregulation.

Quantifying multidimensional control mechanisms of cardiovascular dynamics during multiple concurrent stressors.

Heartbeat regulation is achieved through different routes originating from central autonomic network sources, as well as peripheral control mechanisms. While previous studies successfully characterized cardiovascular regulatory mechanisms during a single stressor, to the best of our knowledge, a combination of multiple concurrent elicitations leading to the activation of different autonomic regulatory routes has not been investigated yet. Therefore, in this study, we propose a novel modeling framework for the quantification of heartbeat regulatory mechanisms driven by different neural routes. The framework is evaluated using two heartbeat datasets gathered from healthy subjects undergoing physical and mental stressors, as well as their concurrent administration. Experimental results indicate that more than 70% of the heartbeat regulatory dynamics is driven by the physical stressor when combining physical and cognitive/emotional stressors. The proposed framework provides quantitative insights and novel perspectives for neural activity on cardiac control dynamics, likely highlighting new biomarkers in the psychophysiology and physiopathology fields. A Matlab implementation of the proposed tool is available online.

Evaluation of the impact of surgical aortic valve replacement on short-term cardiovascular and cerebrovascular controls through spontaneous variability analysis.

We assessed the effect of surgical aortic valve replacement (SAVR) on cardiovascular and cerebrovascular controls via spontaneous variability analyses of heart period, approximated as the temporal distance between two consecutive R-wave peaks on the electrocardiogram (RR), systolic, diastolic and mean arterial pressure (SAP, DAP and MAP) and mean cerebral blood flow (MCBF). Powers in specific frequency bands, complexity, presence of nonlinear dynamics and markers of cardiac baroreflex and cerebral autoregulation were calculated. Variability series were acquired before (PRE) and after (POST) SAVR in 11 patients (age: 76±5 yrs, 7 males) at supine resting and during active standing. Parametric spectral analysis was performed based on the autoregressive model. Complexity was assessed via a local nonlinear prediction approach exploiting the k-nearest-neighbor strategy. The presence of nonlinear dynamics was checked by comparing the complexity marker computed over the original series with the distribution of the same index assessed over a set of surrogates preserving distribution and power spectral density of the original series. Cardiac baroreflex and cerebral autoregulation were estimated by assessing the transfer function from SAP to RR and from MAP to MCBF and squared coherence function via the bivariate autoregressive approach. We found that: i) orthostatic challenge had no effect on cardiovascular and cerebrovascular control markers in PRE; ii) RR variance was significantly reduced in POST; iii) complexity of SAP, DAP and MAP variabilities increased in POST with a greater likelihood of observing nonlinear dynamics over SAP compared to PRE at supine resting; iv) the amplitude of MCBF variations and MCBF complexity in POST remained similar to PRE; v) cardiac baroreflex sensitivity decreased in POST, while cerebrovascular autoregulation was preserved. SAVR induces important changes of cardiac and vascular autonomic controls and baroreflex regulation in patients exhibiting poor reactivity of cardiovascular regulatory mechanisms, while cerebrovascular autoregulation seems to be less affected.

Acute Hemodynamic Changes Associated with Zumba and ZOCA Dance Exercises among Females of Selected Gyms in Lusaka, Zambia

Background: Dynamic exercises are known to elicit hemodynamic changes such as an increase in arterial blood pressure and heart rate. Zumba and ZOCA are part of a fast growing group of dance fitness programmes designed to provide a cardiovascular dynamic workout. Despite their growing popularity, very few studies have been done to provide knowledge regarding the hemodynamic changes associated with these exercises. Methods: Case study in which 27 females took part in either a Zumba or ZOCA class. Using digital blood pressure monitors, recordings of blood pressure and heart rate were taken, firstly, before commencement of the exercise, secondly, after 30 minutes after exercise and thirdly, at the end of the class.Results: Mean baseline blood pressures were 118 (SD = 14) mmHg and 77 (SD = 7) mmHg, systolic and diastolic blood pressures, respectively. After 30 minutes of dancing, mean systolic blood pressure increased to 130 (SD = 19) mmHg (p˂ 0.05) while diastolic blood pressureonly rose to an average of 80 (SD = 8) mmHg (p˃ 0.05). At the end of the class (after the cool down phase) mean systolic blood pressure reduced to 109 (SD = 13) mmHg (p˂0.05) while diastolic blood pressure reduced to 74(SD = 12) mmHg (p˂ 0.05). Conclusions: Zumba and ZOCA elicited significant hemodynamic changes that can be attributed to these exercises stimulating the cardiovascular regulatory mechanisms (e.g central command and exercise-pressor) sufficiently and hence resulting in autonomic adjustmentsthat were concurrent with effective dynamic exercise. Keywords: Blood Pressure, Heart Rate, Aerobic, Dance Exercise

Wavelet Analysis of Microcirculatory Flowmotion Reveals Cardiovascular Regulatory Mechanisms–Data from a Beta-Blocker

A variety of animal models exist for the study of cardiovascular function using many approaches from surgically induced ischemia to genetic manipulation. A murine physiological model was recently proposed for the non-invasive study of peripheral circulation and was strengthened by the wavelet transform analysis (WA) of laser Doppler flowmetry (LDF) signals. WA allows the extraction of cardiac, respiratory, sympathetic, endothelial, and myogenic components from the raw LDF signal. The present study was designed to evaluate the discernment capacity of the model through an analysis of the short-term effects of the well-known hypotensive cardiovascular drug, atenolol. Six male C57/BL6 mice (16 weeks old) were included in the study, with each animal serving as its own control. Following anesthesia with ketamine-xylazine, skin perfusions were continuously assessed in both hindlimbs by LDF during baseline and after two sequential atenolol administrations (2.5 and 5.0 mg/kg, as commonly prescribed). Expected atenolol-induced hypotension was present, associated with a significantly increased heart rate and peripheral perfusion with both dosages. Through the application of WA to the LDF signal, we could detail the mechanisms of the atenolol-induced peripheral perfusion modulation: an immediate amplitude decrease of the cardiac LDF spectrum with an amplitude increase of the sympathetic component (p < 0.05) and the endothelial and myogenic components (non-significant). These data suggested a regulatory crosstalk between the peripheral (baroreceptors) and the microcirculatory units, which ultimately resulted in hypotension, inotropic reduction, and tachycardia. In conclusion, WA offered insight that simply could not be seen with only the perfusion curve and, thus, was an effective tool to investigate this cardiovascular mechanism of regulation.

Sodium Handling and Interaction in Numerous Organs.

Salt (NaCl) is a prerequisite for life. Excessive intake of salt, however, is said to increase disease risk, including hypertension, arteriosclerosis, heart failure, renal disease, stroke, and cancer. Therefore, considerable research has been expended on the mechanism of sodium handling based on the current concepts of sodium balance. The studies have necessarily relied on relatively short-term experiments and focused on extremes of salt intake in humans. Ultra-long-term salt balance has received far less attention. We performed long-term salt balance studies at intakes of 6, 9, and 12 g/day and found that although the kidney remains the long-term excretory gate, tissue and plasma sodium concentrations are not necessarily the same and that urinary salt excretion does not necessarily reflect total-body salt content. We found that to excrete salt, the body makes a great effort to conserve water, resulting in a natriuretic-ureotelic principle of salt excretion. Of note, renal sodium handling is characterized by osmolyte excretion with anti-parallel water reabsorption, a state-of-affairs that is achieved through the interaction of multiple organs. In this review, we discuss novel sodium and water balance concepts in reference to our ultra-long-term study. An important key to understanding body sodium metabolism is to focus on water conservation, a biological principle to protect from dehydration, since excess dietary salt excretion into the urine predisposes to renal water loss because of natriuresis. We believe that our research direction is relevant not only to salt balance but also to cardiovascular regulatory mechanisms.

Blood pressure variability: its relevance for cardiovascular homeostasis and cardiovascular diseases.

Blood pressure (BP) is one of the most dynamic physiologic variables that is routinely measured in clinical practice and is characterized by continuous and significant changes beat-to-beat, over 24 h, day-to-day, and visit-to-visit. Under physiological conditions, these BP variations largely represent a response to environmental stimulations and challenges of daily life aimed at maintaining so-called cardiovascular "homeostasis". However, sustained increases in blood pressure variability (BPV) may also reflect alterations in cardiovascular regulatory mechanisms or underlying pathological conditions and may represent a source of damage to the cardiovascular system. The clinical significance and prognostic implications of these BP variations have been demonstrated by a series of clinical and population studies conducted in recent years, in which increasing BPV has been associated with a higher risk of subclinical organ damage, cardiovascular events, and cardiovascular and all-cause mortality, independent of elevated average BP values. This paper will review the available evidence on the current definitions, classification, and mechanisms responsible for different types of BPV by focusing on their relevance to cardiovascular homeostasis and cardiovascular disease.

Mechanisms underlying the generation of autonomorespiratory coupling amongst the respiratory central pattern generator, sympathetic oscillators, and cardiovagal premotoneurons.

The respiratory rhythm and pattern and sympathetic and parasympathetic outflows are generated by distinct, though overlapping, propriobulbar arrays of neuronal microcircuit oscillators constituting networks utilizing mutual excitatory and inhibitory neuronal interactions, residing principally within the metencephalon and myelencephalon, and modulated by synaptic influences from the cerebrum, thalamus, hypothalamus, cerebellum, and mesencephalon and ascending influences deriving from peripheral stimuli relayed by cranial nerve afferent axons. Though the respiratory and cardiovascular regulatory effector mechanisms utilize distinct generators, there exists significant overlap and interconnectivity amongst and between these oscillators and pathways, evidenced reciprocally by breathing modulation of sympathetic oscillations and sympathetic modulation of neural breathing. These coupling mechanisms are well-demonstrated coordinately in sympathetic- and respiratory-related central neuronal and efferent neurogram recordings and quantified by the findings of cross-correlation, spectra, and coherence analyses, combined with empirical interventions including lesioning and pharmacological agonist and antagonist microinjection studies, baroloading, barounloading, and hypoxic and/or hypercapnic peripheral and/or central chemoreceptor stimulation. Sympathetic and parasympathetic central neuronal and efferent neural discharge recordings evidence classic fast rhythms produced by propriobulbar neuronal networks located within the medullary division of the lateral tegmental field, coherent with cardiac sympathetic nerve discharge. These neural efferent nerve discharges coordinately evidence slow synchronous oscillations, constituted by Traube Hering (i.e., high frequency), Mayer wave (i.e., medium or low frequency), and vasogenic autorhythmicity (i.e., very low frequency) wave spectral bands. These oscillations contribute to coupling neural breathing, sympathetic oscillations, and parasympathetic cardiovagal premotoneuronal activity. The mechanisms underlying the origins of and coupling amongst, these waves remains to be unresolved.

Dose-Dependent Acute Circulatory Fates Elicited by Cadmium Are Mediated by Differential Engagements of Cardiovascular Regulatory Mechanisms in Brain.

Whereas cadmium is a toxicant that has been shown to cause cardiovascular toxicity and mortality in mammals, few mechanistic studies address its acute circulatory actions. The present study assessed the hypothesis that cadmium effects dose-dependent acute circulatory fates via differential participation of the cardiovascular regulatory mechanisms in brain. In Sprague-Dawley rats maintained under propofol anesthesia, cadmium acetate (8 mg/kg, iv) induced significantly high mortality rate within 10 min, concomitant with progressive decline toward zero level of mean arterial pressure (MAP), heart rate (HR), baroreflex-mediated sympathetic vasomotor tone, and carotid blood flow (CBF). There were concurrent tissue anoxia, cessation of microvascular perfusion, reduction of mitochondrial membrane potential and ATP production, and necrotic cell death in the rostral ventrolateral medulla (RVLM), the brain stem site that maintains blood pressure and sympathetic vasomotor tone. On the other hand, a lower-dose of cadmium (4 mg/kg, iv) resulted in only a transient decrease in MAP that was mirrored by an increase in CBF and baroreflex-mediated sympathetic vasomotor tone, minor changes in HR, along with transient hypoxia, and apoptotic cell death in RVLM. We conclude that cadmium elicits dose-dependent acute cardiovascular effects with differential underlying biochemical and neural mechanisms. At a higher-dose, cadmium induces high mortality by effecting acute cardiovascular collapse via anoxia, diminished tissue perfusion, mitochondrial dysfunction and bioenergetics failure that echo failure of cerebral autoregulation, leading to necrosis, and loss of functionality in RVLM. On the other hand, a lower-dose of cadmium elicits low mortality, transient decrease in arterial pressure, and hypoxia and apoptosis in RVLM that reflect sustained cerebral autoregulation.