We hypothesized that sympathetic hyperactivity and parasympathetic insuficiency in spontaneously hypertensive rats (SHR) underlie their exaggerated cardiovascular response to acute stress and impaired adaptation to repeated restraint stress exposure compared to Wistar-Kyoto rats (WKY). Cardiovascular responses to single (120 min) or repeated (daily 120 min for 1 week) restraint were measured by radiotelemetry and autonomic balance was evaluated by power spectral analysis of systolic blood pressure variability (SBPV) and heart rate variability (HRV). Baroreflex sensitivity (BRS) was measured by the pharmacological Oxford technique. Stress-induced pressor response and vascular sympathetic activity (low-frequency component of SBPV) were enhanced in SHR subjected to single restraint compared to WKY, whereas stress-induced tachycardia was similar in both strains. SHR exhibited attenuated cardiac parasympathetic activity (high-frequency component of HRV) and blunted BRS compared to WKY. Repeated restraint did not affect the stress-induced increase in blood pressure. However, cardiovascular response during the post-stress recovery period of the 7th restraint was reduced in both strains. The repeatedly restrained SHR showed lower basal heart rate during the dark (active) phase and slightly decreased basal blood pressure during the light phase compared to stress-naive SHR. SHR subjected to repeated restraint also exhibited attenuated stress-induced tachycardia, augmented cardiac parasympathetic activity, attenuated vascular sympathetic activity and improved BRS during the last seventh restraint compared to single-stressed SHR. Thus, SHR exhibited enhanced cardiovascular and sympathetic responsiveness to novel stressor exposure (single restraint) compared to WKY. Unexpectedly, the adaptation of cardiovascular and autonomic responses to repeated restraint was more effective in SHR.
- MeSH
- autonomní nervový systém * patofyziologie MeSH
- baroreflex * fyziologie MeSH
- fyzické omezení * MeSH
- fyziologická adaptace * fyziologie MeSH
- hypertenze * patofyziologie MeSH
- krevní tlak * fyziologie MeSH
- krysa rodu rattus MeSH
- potkani inbrední SHR * MeSH
- potkani inbrední WKY * MeSH
- psychický stres patofyziologie MeSH
- srdeční frekvence * fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Spontaneously hypertensive rats (SHR) are characterized by sympathetic hyperactivity and insufficient parasympathetic activity, and their high blood pressure (BP) can be lowered by long-term inhibition of the renin-angiotensin system. The aim of our study was to determine the influence of chronic inhibition of angiotensin converting enzyme (ACE) by captopril on cardiovascular regulation by the sympathetic and parasympathetic nervous system. Implanted radiotelemetric probes or arterial cannulas were used to measure mean arterial pressure (MAP), heart rate (HR), and arterial baroreflex in adult SHR and Wistar-Kyoto (WKY) rats under basal or stress conditions. MAP and the low-frequency component of systolic blood pressure variability (LF-SBPV, marker of sympathetic activity) were greater in SHR than in WKY rats. Under basal conditions chronic captopril treatment reduced both parameters more effectively in SHR, and the same was true during acute restraint stress. HR was similar in control rats of both strains, but WKY rats showed greater heart rate variability (HRV), indicating higher parasympathetic activity. Captopril administration increased HR in both strains, whereas HRV was decreased only in WKY. Chronic captopril treatment improved the impaired baroreflex-HR control in SHR by increasing the sensitivity but not the capacity of vagal arm of arterial baroreflex. Captopril treatment attenuated BP changes elicited by dimethylphenylpiperazinium (DMPP, agonist of nicotinic acetylcholine receptors), especially in SHR, indicating that sympathetic nerve transmission is facilitated by angiotensin II more in hypertensive than in normotensive animals. Thus, chronic ACE inhibition improves baroreflex sensitivity and lowers BP through both central and peripheral attenuation of sympathetic tone.
- MeSH
- baroreflex * účinky léků MeSH
- hypertenze farmakoterapie patofyziologie enzymologie MeSH
- inhibitory ACE * farmakologie MeSH
- kaptopril * farmakologie MeSH
- krevní tlak * účinky léků MeSH
- krysa rodu rattus MeSH
- potkani inbrední SHR MeSH
- potkani inbrední WKY MeSH
- srdeční frekvence * účinky léků MeSH
- sympatický nervový systém * účinky léků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Impaired autonomic modulation and baroreflex sensitivity (BRS) have been reported during and after COVID-19. Both impairments are associated with negative cardiovascular outcomes. If these impairments were to exist undetected in young men after COVID-19, they could lead to negative cardiovascular outcomes. Fatigue is associated with autonomic dysfunction during and after COVID-19. It is unclear if fatigue can be used as an indicator of impaired autonomic modulation and BRS after COVID-19. This study aims to compare parasympathetic modulation, sympathetic modulation, and BRS between young men who had COVID-19 versus controls and to determine if fatigue is associated with impaired autonomic modulation and BRS. Parasympathetic modulation as the high-frequency power of R-R intervals (lnHFR-R), sympathetic modulation as the low-frequency power of systolic blood pressure variability (LFSBP), and BRS as the -index were measured by power spectral density analysis. These variables were compared between 20 young men who had COVID-19 and 24 controls. Independent t-tests and Mann-Whitney U tests indicated no significant difference between the COVID-19 and the control group in: lnHFR-R, P=0.20; LFSBP, P=0.11, and -index, P=0.20. Fatigue was not associated with impaired autonomic modulation or BRS. There is no difference in autonomic modulations or BRS between young men who had COVID-19 compared to controls. Fatigue did not seem to be associated with impaired autonomic modulation or impaired BRS in young men after COVID-19. Findings suggest that young men might not be at increased cardiovascular risk from COVID-19-related dysautonomia and impaired BRS.
- MeSH
- autonomní nervový systém MeSH
- baroreflex fyziologie MeSH
- COVID-19 * MeSH
- kardiovaskulární systém * MeSH
- krevní tlak fyziologie MeSH
- lidé MeSH
- srdeční frekvence fyziologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- antihypertenziva terapeutické užití MeSH
- baroreflex MeSH
- hypertenze * diagnóza chirurgie MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Blood flows and pressures throughout the human cardiovascular system are regulated in response to various dynamic perturbations, such as changes to peripheral demands in exercise, rapid changes in posture, or loss of blood from hemorrhage, via the coordinated action of the heart, the vasculature, and autonomic reflexes. To assess how the systemic and pulmonary arterial and venous circulation, the heart, and the baroreflex work together to effect the whole-body responses to these perturbations, we integrated an anatomically-based large-vessel arterial tree model with the TriSeg heart model, models capturing nonlinear characteristics of the large and small veins, and baroreflex-mediated regulation of vascular tone and cardiac chronotropy and inotropy. The model was identified by matching data from the Valsalva maneuver (VM), exercise, and head-up tilt (HUT). Thirty-one parameters were optimized using a custom parameter-fitting tool chain, resulting in an unique, high-fidelity whole-body human cardiovascular systems model. Because the model captures the effects of exercise and posture changes, it can be used to simulate numerous clinical assessments, such as HUT, the VM, and cardiopulmonary exercise stress testing. The model can also be applied as a framework for representing and simulating individual patients and pathologies. Moreover, it can serve as a framework for integrating multi-scale organ-level models, such as for the heart or the kidneys, into a whole-body model. Here, the model is used to analyze the relative importance of chronotropic, inotropic, and peripheral vascular contributions to the whole-body cardiovascular response to exercise. It is predicted that in normal physiological conditions chronotropy and inotropy make roughly equal contributions to increasing cardiac output and cardiac power output during exercise. Under upright exercise conditions, the nonlinear pressure-volume relationship of the large veins and sympathetic-mediated venous vasoconstriction are both required to maintain preload to achieve physiological exercise levels. The developed modeling framework is built using the open Modelica modeling language and is freely distributed.
- MeSH
- baroreflex * fyziologie MeSH
- cvičení * MeSH
- kardiovaskulární systém * MeSH
- krevní tlak fyziologie MeSH
- lidé MeSH
- postura těla fyziologie MeSH
- srdeční frekvence fyziologie MeSH
- systémová analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
To characterize the differences in baroreflex sensitivity (BRS), blood pressure (BP), heart rate (HR) and respiration rate (RR) in preterm infants with a similar postconceptional age reached by various combinations of gestational and postnatal ages. To detect potential sex differences in assessed cardiovascular parameters. The study included 49 children (24 boys and 25 girls), postconceptional age 34.6+/-1.9 weeks. Two subgroups of infants were selected with the similar postconceptional age (PcA) and current weight, but differing in gestational (GA) and postnatal (PnA) ages, as well as two matched subgroups of boys and girls. Blood pressure (BP) was recorded continuously using Portapres device (FMS). A stationary segment of 250 beat-to-beat BP values was analyzed for each child. Baroreflex sensitivity (BRS) was calculated by cross-correlation sequence method. Despite the same PcA age and current weight, children with longer GA had higher BRS, diastolic and mean BP than children with shorter GA and longer PnA age. Postconceptional age in preterm infants is a parameter of maturation better predicting baroreflex sensitivity and blood pressure values compared to postnatal age. Sex related differences in BRS, BP, HR and RR were not found in our group of preterm infants.
- MeSH
- baroreflex * MeSH
- časové faktory MeSH
- dechová frekvence MeSH
- gestační stáří MeSH
- kojenec MeSH
- krevní tlak * MeSH
- lidé MeSH
- novorozenec nedonošený * MeSH
- novorozenec MeSH
- předčasný porod patofyziologie MeSH
- sexuální faktory MeSH
- srdeční frekvence * MeSH
- věkové faktory MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- mužské pohlaví MeSH
- novorozenec MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Aims: To test the hypothesis that spinal cord stimulation (SCS) acutely improves heart rate variability (HRV) and baroreceptor sensitivity (BRS) in patients with heart failure (HF). Methods: SCS (15 minutes) was delivered in four different settings: 90% of maximal tolerated stimulation amplitude (MTA) targeting the T1-T4 spinal cord segments (SCS90T1-4), 60% of MTA (SCS60T1-4), 90% of MTA with cranial (SCS90CR) and caudal (SCS90CA) electrode configuration. HRV and BRS were recorded continuously and stimulation was compared to device off. Results: Fifteen HF patients were included. SCS90T1-4 did not change the standard deviation of intervals between normal beats (SDNN, p = 0.90), BRS (p = 0.55) or other HRV parameters. In patients with baseline SDNN <50 ms, SCS90T1-4 significantly increased SDNN (p = 0.004). Conclusions: Acute SCS at 60-90% of MTA targeting upper thoracic spinal cord segments does not improve autonomic balance or baroreceptor sensitivity in unselected patients with heart failure but may improve HRV in patients with low SDNN.
- MeSH
- autonomní nervový systém MeSH
- baroreflex MeSH
- lidé MeSH
- míšní stimulace MeSH
- srdeční selhání MeSH
- Check Tag
- lidé MeSH
Úvod: Dynamika vývoja kardiovaskulárneho systému a jeho regulácií vo včasnom postnatálnom období v značnej miere závisí od zrelosti novorodenca. Cieľom práce bolo zistiť vzťah medzi kardiovaskulárnymi parametrami (frekvenciou srdca a jej variabilitou, pulzovým intervalom, systémovým tlakom krvi a parametrami odrážajúcimi intrauterinný a postnatálny vývoj a rast (gestačný vek, postkoncepčný vek, pôrodná a aktuálna hmotnosť) v skupine nedonosených detí v prvých týždňoch života. Metodika: U 43 nedonosených detí rôzneho gestačného veku, pôrodnej a aktuálnej hmotnosti bol v priemernom postkoncepčnom veku 34,6 týždňa kontinuálne a neinvazívne registrovaný krvný tlak a frekvencia srdca. Tlak krvi bol kontinuálne registrovaný pomocou prístroja Portapres (FMS) počas 2–5 minút v pokoji za štandardných podmienok. U každého dieťaťa bol analyzovaný stacionárny segment záznamu obsahujúci štandardne 250 tep po tepu (beat-to-beat) hodnôt tlaku krvi. U 35 detí bola spektrálnou analýzou zisťovaná variabilita pulzových intervalov odrážajúca variabilitu frekvencie srdca (celkový spektrálny výkon a výkony vo vysokofrekvenčnej – HF a nízkofrekvenčnej – LF oblasti). Výsledky: Korelačnou analýzou testami (Pearsonov, resp. Spearmanov korelačný koeficient) boli zistené pozitívne korelácie medzi gestačným, postkoncepčným vekom, pôrodnou a aktuálnou hmotnosťou a priemernou dĺžkou pulzového intervalu (IBI), celkovým spektrálnym výkonom variability pulzových intervalov (total power), ako aj spektrálnymi výkonmi v LF a HF pásme, a priemernou hodnotou diastolického i stredného tlaku krvi. Signifikantná negatívna korelácia bola medzi uvedenými anamnestickými parametrami a priemernou frekvenciou srdca a frekvenciou dýchania. Záver: U nedonosených novorodencov s vyšším gestačným a postkoncepčným vekom, pôrodnou a aktuálnou hmotnosťou sme zaznamenali vyšší celkový spektrálny výkon variability frekvencie srdca, nižšiu priemernú frekvenciu srdca a vyšší stredný a diastolický tlak krvi. Tieto zmeny a zistené závislosti poukazujú na zvyšujúci sa vplyv baroreflexov a postupné dozrievanie regulácie kardiovaskulárneho systému autonómnym nervovým systémom nedonosených novorodencov.
Relationships between the values of heart rate variability and blood pressure and parameters of growth and development in premature infants Introduction: The dynamics of the development of the cardiovascular system in the early postnatal period also depends on the maturity of the newborn. The aim of the study was to determine the relationships between cardiovascular parameters – heart rate variability, its components (LF, HF), pulse intervals (interbeat intervals – IBI), heart rate, systemic blood pressure and parameters reflecting development and growth – gestational age, postconceptional age, birth and actual weight in the group of premature babies in the first weeks of life. Methods: In 43 premature infants of various gestational ages, birth and actual weights, at a mean postconception age of 34.6 weeks, blood pressure and heart rate were continuously and non-invasively recorded. Blood pressure was recorded continuously for 2–5 minutes under standard conditions using a Portapres device (FMS). For each child, a stationary segment of the record containing 250 beat-to-beat blood pressure values was analyzed. The variability of interbeat intervals was determined by spectral analysis (total power, powers in high-frequency and low-frequency bands) in 35 children. Results: Correlation tests (Pearson´s and Spearman´s) revealed positive correlations between gestational, postconceptional age, birth and actual weight and mean value of pulse intervals (IBI), spectral total power of the IBI variability, as well as spectral powers in HF and LF bands, and diastolic and mean blood pressure. There was a significant negative correlation between the ages and weights and mean heart and respiratory rate. Conclusion: Preterm infants with higher gestational and postconceptional age, birth and actual weight have higher total power of heart rate variability.This is not only a consequence of the increase in spectral power in the HF band, but also in the LF band, which through the activities of the sympathetic and parasympathetic systems reflects mainly baroreflex activity. Together, the mean heart rate is lower and blood pressure, diastolic and mean are higher. The identified relationships point to the increasing baroreflex sensitivity and to the maturation of regulatory circuits of the cardiovascular system in premature infants.
- Klíčová slova
- variabilita srdeční frekvence,
- MeSH
- baroreflex MeSH
- klinická studie jako téma MeSH
- krevní tlak MeSH
- lidé MeSH
- novorozenec nedonošený * fyziologie MeSH
- novorozenec MeSH
- srdeční frekvence MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- práce podpořená grantem MeSH
Autism spectrum disorder (ASD) represents a serious neurodevelopmental disorder associated with autonomic nervous system dysregulation. The aim was to study complex cardiovascular autonomic regulation using heart rate variability (HRV) and systolic blood pressure variability (SBPV) linear/non-linear analysis at rest and during orthostasis, and to assess plasma levels of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) in autistic children. Twenty-five ASD boys and 25 age and gender-matched children at the age 7-15 years were examined. After venous blood taking, continuous ECG and blood pressure biosignals were recorded at rest and during orthostasis. Evaluated parameters: RR intervals, high- and low-frequency band of HRV spectral analysis (HF-HRV, LF-HRV), symbolic dynamics parameters 0V%, 1V%, 2LV%, 2UV%, low- and high-frequency band of SBPV (LF-SBPV, HF-SBPV), systolic, diastolic, mean blood pressure, EGF, VEGF plasma levels. RR intervals were significantly shortened and the HF-HRV, LF-SBPV, HF-SBPV parameters were significantly lower at rest, the HF-HRV and LF-SBPV remained lower during orthostasis in autistic children compared to controls (p<0.05). EGF plasma levels were significantly lower in ASD compared to controls (p=0.046). No significant differences were found in remaining parameters. Our study revealed tachycardia, cardiovagal underactivity, and blunted sympathetic vasomotor regulation at rest and during orthostasis in autistic children. Additionally, complex heart rate dynamics are similar in autistic children than controls. Furthermore, EGF was reduced in autistic children without significant correlations with any autonomic parameters. We suggest that the abnormal complex cardiovascular reflex control could contribute to understanding the pathway linking autonomic features and autism.
- MeSH
- autonomní nervový systém patofyziologie MeSH
- baroreflex MeSH
- biologické markery krev MeSH
- dítě MeSH
- epidermální růstový faktor krev MeSH
- krevní tlak * MeSH
- lidé MeSH
- mladiství MeSH
- poruchy autistického spektra krev diagnóza patofyziologie MeSH
- srdce inervace MeSH
- srdeční frekvence * MeSH
- vaskulární endoteliální růstový faktor A krev MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
