Heart Rate Rhythm Research Articles

Autonomic control of cardiorespiratory coupling in healthy subjects under moderate physical exercises

Aim of the study is to apply the analysis of phase dynamics to investigation of the coupling patterns between heart rate variability, respiration and peripheral circulation in healthy subjects at rest and after moderate physical exercises. Material and Methods ― 30-minutes electrocardiogram (ECG), photoplethysmogram (PPG) and respiration records were obtained from healthy subjects aged 22±2 (mean ± standard deviation) before and after active Martine Kushelevsky test (20 squats in 30 seconds). The coherence function was estimated between all the signals from each subject, and the phase dynamics modeling was used to detect the directional coupling in high-frequency (HF; 0.14-0.40 Hz) and low-frequency ranges (LF; 0.04-0.14 Hz). Results ― At rest (before the physical activity) no statistically significant couplings were detected between the HF rhythms of respiration and heart rate (RR intervals). For the HF rhythms in respiration and PPG, the influence respirationPPG was detected. No couplings were detected between the LF rhythms. After the moderate physical exercise, predominant direction of the influence was RR intervals  PPG in the LF range and both RR intervals  respiration and PPG  respiration in the HF range. The influence PPG  respiration was delayed by several seconds. Conclusion ― adaptation to the moderate physical activity has led to the decrease in the overall coherence and changes in patterns of directional coupling between the LF and HF rhythms in respiration, heart rate and peripheral circulation. The obtained results confirm nonlinearity and complexity of the coupling patterns in cardiovascular system.

Синтез і кардіотропна дія [3-алліл-4-(41-метоксифеніл)-3Н-тіазол-2-іліден](32-трифлуорометилфеніл)аміну гідроброміду в білих щурів

У роботі наведено результати експериментального дослідження, присвяченого синтезу та вивченню кардіотропних властивостей оригінального похідного тіазолу – [3-алліл-4-(41-мето ксифеніл)-3Н-тіазол-2-іліден]-(32-трифлуорометилфеніл)аміну гідроброміду з умовною назвою Кардіазол, як перспективного вітчизняного кардіопротекторного лікарського засобу. Запропоновано зручний та ефективний метод отримання субстанції Кардіазолу, який придатний для промислових масштабів. У серії in vitro дослідів встановлено, що Кардіазол характеризується виразною кардіотропною дією, співмірною з мілдронатом. Встановлено, що за внутрішньоочеревинного введення білим щурам у дозі 7 мг/кг Кардіазол спричиняє гіпотензивний ефект і призводить до зниження артеріального тиску на 12,8 % і 16,7 % через 60 хв і 180 хв після введення, не впливає на частоту та ритм серцевих скорочень. Встановлено, що застосування Кардіазолу викликає кардіопротекторний ефект і спричиняє зниження рівня летальності білих щурів за адреналінової моделі інфаркту міокарда, покращує біохімічний профіль маркерів патологічного процесу (АСТ, ЛДГ, МВ-КФК) і нормалізує зміни на електрокардіограмі.

Lack of daily heart rate rhythms in Adélie penguin chicks during the polar day

AbstractDaily rhythms enable organisms to adapt to daily fluctuations in environmental factors. Do organisms still exhibit 24-h rhythms when living in habitats without obvious daily cycles in external signals? To answer this question, we measured the heart rates of six Adélie penguin (Pygoscelis adeliae) chicks on Inexpressible Island during the polar day between 15 and 21 January 2019. Averaged heart rates were between 186 and 233 beats/min for individual chicks. Both fast Fourier transformation and autocorrelation were employed to assess the daily rhythmicity. Based on fast Fourier transformation, a significant contribution of daily rhythm in heart rate variation was found only in one individual. Small effect size of significant autocorrelation coefficients was found in two individuals, while there was no significant autocorrelation coefficient for 24-h time lag in four other individuals. In summary, no prevailing daily rhythm of heart rate was found in these Adélie penguin chicks. We propose that the lack of daily rhythm in Adélie penguin chicks could be an adaptation to the local environment in the polar regions, but that the adaptive value thereof remains to be investigated.

If Channel Inhibition - Ivabradine for the Treatment of Heart Failure

The novel first-in-class If channel antagonist, Ivabradine, is effective in improving clinical outcomes and functional capacity, in patients with HF, as well as demonstrating useful anti-anginal and protective anti-ischaemic effects. It can help improve heart rate control and can be usefully co-administered with beta blockers on HFrEF patients with residually elevated resting sinus rhythm heart rate. We review the clinical trial evidence for the benefits of Ivabradine in the treatment of heart failure.

Rapid screening for cardiac arrhythmias in competition draft horses

Cardiac arrhythmias may cause decreased performance and sudden death during exercise. Our objectives were: (1) to determine prevalence of unrecognised arrhythmias in a population of competition draft horses by performing short duration screening electrocardiograms (ECGs) at rest; and (2) to assess utility of a commercial handheld device for recording equine ECGs. Owners or trainers of 244 draft horses (age 0.5-16 years), including 82 Percherons, 69 Belgians, 69 Clydesdales, 11 Belgian mules, 8 Shires, and 5 Percheron mules, were queried to determine signalment, performance history, and known arrhythmias. All horses were auscultated for 30 s and ECGs were obtained in 204 horses using a handheld recording device (AliveCor®). ECGs were reviewed for quality and used to determine heart rate (HR) and rhythm. When ECG tracing quality permitted, PQ and QT intervals were also measured. ECGs displaying RR intervals adequate for HR determination and rhythm assessment were recorded from 161 horses (79%) while tracings with consistent P waves, QRS complexes, and T waves were recorded from only 47 horses (23%). Four arrhythmias were detected by both auscultation and ECG: atrial fibrillation (1), premature complexes (1), and second-degree atrioventricular block (2). None of these horses had a history of poor performance or previous recognition of an arrhythmia. The prevalence of unrecognised, and potentially clinically significant, arrhythmias in draft horses at rest appears to be low (2/244; 0.8%, 95% confidence interval 0.1-2.9%). Longer recordings at rest, as well as recordings during and immediately after exercise, would likely have revealed a higher prevalence of arrhythmias.

Abstract P179: Time Restricted Feeding Improves Blood Pressure and Heart Rate Rhythms as Well as Activation of NOS3 and AMP Kinase in Mice on a Chronic High Fat Diet

Irregular timing of food intake increases cardiometabolic disease and hypertension risk. A chronic high fat diet (HFD) leads to loss of endothelial function and reduced activation of endothelial NO synthase (NOS3). We hypothesized that restricting food availability to the active period in mice on HFD will restore the blood pressure rhythm and NOS3 activation. Mice (male 8-week old, C57BL/6J) were given normal diet (ND; 10% fat) or HFD (45% fat) for 20 weeks ad lib. During the final 2 weeks, food availability was limited to the active phase (restricted feed, RF) in half the HFD mice. Mean arterial pressure (MAP), heart rate (HR), and locomotor activity were measured by telemetry. At the end of the study, 24 hr MAP, HR, and locomotor activity were similar in all groups. However, RF significantly increased the difference in MAP and HR between active and inactive periods in mice on HFD (MAP: ND: 16±0.7 mmHg, HFD: 15±0.8 mmHg, HFD+RF: 18±0.9 mmHg, n=6-8, p=0.01; HR: ND: 68±5.1 bpm, HFD: 69±6.5 bpm, HFD+RF: 113±7.9 bpm, n=6-8, p<0.01). The active-inactive difference in activity was similar in ND, HFD, and HFD+RF (p>0.05). At the end of the study, aorta (Ao) and renal vessels (RV) were isolated in the middle of the active period (ZT17). Western blotting revealed that diet or RF did not affect total NOS3, total Akt kinase (Akt), pAkt(S473), or total AMPK abundance in either vascular bed. pNOS3(S1177) abundance in Ao was improved by RF in HFD mice (ND: 8.5±4.7 rdu, HFD: 0.5±0.2 rdu, HFD+RF: 2.1±0.6 rdu, n=4, p=0.06). RF in HFD mice increased aortic pAMPK(T172) activation at ZT17 but not in renal vessels (Ao: ND: 0.2±0.1 rdu, HFD: 0.2±0.1 rdu, HFD+RF: 0.7±0.2 rdu, n=4-5, p=0.01; RV: ND: 0.8±0.2 rdu, HFD: 0.5±0.1 rdu, HFD+RF: 0.7±0.2 rdu, n=5-6, p=0.30). Plasma nitrite was significantly decreased in HFD and HFD+RF mice at ZT17 compared to ND mice (HFD: 0.6±0.04 μM; HFD+RF: 0.7±0.03 μM; ND: 1.4±0.3 μM; n=6, p=0.03). Our findings indicate that RF increases the differences in diurnal MAP and HR as well as increased activation of NOS3 and AMP kinase in mice on a chronic high fat diet. In conclusion, these results suggest that timing of food intake on a HFD improves MAP and HR rhythms possibly via increased activation of NOS3 and AMPK.

Cardiac autonomic activity during sleep deprivation with and without caffeine administration

Caffeine is often consumed to mitigate degraded alertness associated with sleep deprivation. Both caffeine and sleep deprivation have been implicated in cardiovascular disease, but evidence is largely anecdotal. We determined the effects of sleep deprivation and caffeine on markers of cardiac autonomic activity. Twelve healthy young adults completed an 18-day laboratory study. They were exposed to three 48 h sessions of acute total sleep deprivation (TSD), each separated by three recovery days. In randomized, counter-balanced order, subjects received 0 mg (placebo), 200 mg, or 300 mg of caffeine at 12 h intervals during each sleep deprivation session. Every 2 h during scheduled wakefulness, a 15-minute neurobehavioral task battery was administered, during which heart rate (HR) and the high frequency (HF) component of the HR variability power spectrum (HF-HRV) were measured. Caffeine administration decreased HR and increased HF-HRV, indicating elevated parasympathetic activity. The 300 mg caffeine dose did not significantly affect autonomic activity to a greater extent than the 200 mg dose. There was no significant effect of 48 h of TSD on HR, whereas there was a small increase across hours awake in HF-HRV. There was no significant interaction of TSD with caffeine. Circadian rhythmicity in HR and HF-HRV surpassed the magnitude of the effects of caffeine and TSD. Caffeine and acute TSD thus produced only modest changes in cardiac autonomic activity, unlikely to have immediate clinical implications in healthy young adults. However, further research is needed to determine the long-term effects of chronic exposure to sleep loss and/or caffeine on cardiac health, and to determine the generalizability of our findings to non-healthy populations.

Circadian dysfunction in the Q175 model of Huntington's disease: Network analysis.

Disturbances in sleep/wake cycle are a common complaint of individuals with Huntington's disease (HD) and are displayed by HD mouse models. The underlying mechanisms, including the possible role of the circadian timing system, have been the topic of a number of recent studies. The (z)Q175 mouse is a knock-in model in which the human exon 1 sequence of the huntingtin gene is inserted into the mouse DNA with approximately 190 CAG repeats. Among the numerous models available, the heterozygous Q175 offers strong construct validity with a single copy of the mutation, genetic precision of the insertion and control of mutation copy number. In this review, we will summarize the evidence that this model exhibits disrupted diurnal and circadian rhythms in locomotor activity. We found overwhelming evidence for autonomic dysfunction including blunted daily rhythms in heart rate and core body temperature (CBT), reduced heart rate variability, and almost a complete failure of the sympathetic arm of the autonomic nervous system to function during the baroreceptor reflex. Mechanistically, the Q175 mouse model exhibits deficits in the neural output of the central circadian clock, the suprachiasmatic nucleus along with an enhancement of at least one type of potassium current in these neurons. Finally, we report a novel network analysis examining the phase coherence between activity, CBT, and cardiovascular measures. Such analyses found that even young Q175 mutants (heterozygous or homozygous) show coherence degradation, and suggests that loss of phase coherence is a variable that should be considered as a possible biomarker for HD.

Development of a Clinical Interface for a Novel Newborn Resuscitation Device: Human Factors Approach to Understanding Cognitive User Requirements.

BackgroundA novel medical device has been developed to address an unmet need of standardizing and facilitating heart rate recording during neonatal resuscitation. In a time-critical emergency resuscitation, where failure can mean death of an infant, it is vital that clinicians are provided with information in a timely, precise, and clear manner to capacitate appropriate decision making. This new technology provides a hands-free, wireless heart rate monitoring solution that easily fits the clinical pathway and procedure for neonatal resuscitation.ObjectiveThis study aimed to understand the requirements of the interface design for a new device by using a human factors approach. This approach combined a traditional user-centered design approach with an applied cognitive task analysis to understand the tasks involved, the cognitive requirements, and the potential for error during a neonatal resuscitation scenario.MethodsFourteen clinical staff were involved in producing the final design requirements. Two pediatric doctors supported the development of a visual representation of the activities associated with neonatal resuscitation. This design was used to develop a scenario-based workshop. Two workshops were carried out in parallel and involved three pediatric doctors, three neonatal nurses, two advance neonatal practitioners, and four midwives. Both groups came together at the end to reflect on the findings from the separate sessions.ResultsThe outputs of this study have provided a comprehensive description of information requirements during neonatal resuscitation and enabled product developers to understand the preferred requirements of the user interface design for the device. The study raised three key areas for the designers to consider, which had not previously been highlighted: (1) interface layout and information priority, as heart rate should be central and occupy two-thirds of the screen; (2) size and portability, to enable positioning of the product local to the baby’s head and allow visibility from all angles; and (3) auditory feedback, to support visual information on heart rate rhythm and reliability of the trace with an early alert for intervention while avoiding parental distress.ConclusionsThis study demonstrates the application of human factors and the applied cognitive task analysis method, which identified previously unidentified user requirements. This methodology provides a useful approach to aid development of the clinical interface for medical devices.

Light affects heart rate's 24-h rhythmicity in intensive care unit patients: an observational study.

Intensive care unit (ICU) patients experience two affronts to normal 24-h rhythms: largely internal events such as medication and external factors such as light, noise and nursing interventions. We investigated the impact of light variance within an ICU on 24-h rhythmicity of three key physiological parameters: heart rate (HR), mean arterial blood pressure (MAP) and body temperature (BT) in this patient population. Patients were assigned to beds either in the 'light' or 'dark' side within a single ICU. An actigraph continuously recorded light intensity for a 24-72-h period. Measurements of HR, MAP and BT were recorded every 30 min. HR, MAP and BT did not follow 24-h rhythmicity in all patients. Higher light exposure in the Light Side of the ICU (122·3 versus 50·6lx) was related to higher HR (89·4 versus 79·8 bpm), which may translate to clinically relevant outcomes in a larger sample. Duration of stay, the one clinical outcome measured in this study, showed no significant variation between the groups (p = 0·147). ICU patients are exposed to varying light intensities depending on bed positioning relative to natural sunlight, affecting the 24-h rhythm of HR. Larger, well-controlled studies also investigating the effect of relevant light intensity are indicated. Light is a variable that can be manipulated in the constrained environment of an ICU, thus offering an avenue for relatively unobtrusive interventions.

Sensory contact to the stressor prevents recovery from structural and functional heart damage following psychosocial trauma

Cardiovascular disorders (CVD) and posttraumatic stress disorder (PTSD) are highly comorbid, but the underlying mechanisms are not fully understood. Chronic psychosocial stress was induced in male mice by chronic subordinate colony housing (CSC), a pre-clinically validated mouse model for PTSD. Cardiac structure and function were assessed on day 20 of the CSC paradigm. Following CSC, mice were kept in different sensory contact modalities to the last aggressor for 30 days, and development of cardiac function and behavioral aspects were determined. Here we show that psychosocial trauma affects heart structure by disturbing cell-to-cell integrity of cardiomyocytes, causes tachycardia, disturbance of diurnal heart rate rhythmicity and behavioral deficits in a mouse model for PTSD. Structural and functional alterations were also found in cardiomyocytes upon in vitro treatment with pro-inflammatory cytokines typically increased after psychosocial trauma. Interestingly, sensory contact to the aggressor subsequent to psychosocial trauma prohibits functional and structural heart recovery, while isolation was beneficial for cardiac but detrimental for mental health. These findings contribute to our understanding of potential mechanisms underlying the high comorbidity of CVD and PTSD.

초등학교 체조선수의 일회성운동이 혈압, 심박수, 혈당, 체력의 주기리듬과 dipping에 미치는 영향

초등학교 체조선수의 일회성운동이 혈압, 심박수, 혈당, 체력의 주기리듬과 dipping에 미치는 영향

Circadian rhythms of cardiovascular autonomic function: Physiology and clinical implications in neurodegenerative diseases.

Circadian rhythms of blood pressure and heart rate are regulated by a biological clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which modulates the autonomic nervous system activity directed to the heart and blood vessels. Humoral mediators released with periodicity induced by the SCN as well as sleep are also important factors. Disruption of physiological cardiovascular circadian rhythms has important clinical implications, as it is associated with increased morbidity and mortality. In this review, firstly we will give an overview on the neuroanatomic and physiologic aspects of cardiovascular circadian rhythms. Secondly we will examine how to assess them in clinical practice. Finally we will discuss certain neurodegenerative diseases in which there is an alteration of these rhythms, such as Parkinson's disease and Alzheimer's disease.

Angiotensin-(1-7) Receptor Mas in Hemodynamic and Thermoregulatory Dysfunction After High-Level Spinal Cord Injury in Mice: A Pilot Study.

Spinal cord injury (SCI) above mid-thoracic levels leads to autonomic dysfunction affecting both the cardiovascular system and thermoregulation. The renin-angiotensin system (RAS) which is a potent regulator of blood pressure, including its novel beneficial arm with the receptor Mas could be an interesting target in post-SCI hemodynamics. To test the hypothesis that hemodynamics, activity and diurnal patterns of those are more affected in the Mas deficient mice post-SCI we used a mouse model of SCI with complete transection of spinal cord at thoracic level 4 (T4-Tx) and performed telemetric monitoring of blood pressure (BP) and heart rate (HR). Our data revealed that hypothermia deteriorated physiological BP and HR control. Preserving normothermia by keeping mice at 30°C prevented severe hypotension and bradycardia post-SCI. Moreover, it facilitated rapid return of diurnal regulation of BP, HR and activity in wild type (WT) mice. In contrast, although Mas deficient mice had comparable reacquisition of diurnal HR rhythm, they showed delayed recovery of diurnal rhythmicity in BP and significantly lower nocturnal activity. Exposing mice with T4-Tx (kept in temperature-controlled cages) to 23°C room temperature for one hour at different time-points post-SCI, demonstrated their inability to maintain core body temperature, Mas deficient mice being significantly more impaired than WT littermates. We conclude that Mas deficient mice were more resistant to acute hypotension, delayed nocturnal recovery, lower activity and more severely impaired thermoregulation. The ambient temperature had significant effect on hemodynamics and, thus it should be taken into account when assessing cardiovascular parameters post-SCI in mice.

Impact of repeated kindled seizures on heart rate rhythms, heart rate variability, and locomotor activity in rats

Although an impact of epilepsy on circadian rhythmicity is well-recognized, there are profound gaps in our understanding of the influence of seizures on diurnal rhythms. The effect on activity levels and heart rate is of particular interest as it might contribute to the disease burden. The kindling model with telemetric transmitter implants provides excellent opportunities to study the consequences of focal and generalized seizures under standardized conditions.Data from kindled rats with generalized seizures revealed an increase in activity and heart rate during the resting phase. Total and short-term heart rate variabilities were not affected by electrode implantation or seizure induction.Ictal alterations in heart rate associated with generalized seizures were characterized by a biphasic bradycardia with an immediate drop of heart rate followed by a transient normalization and a second more steady decrease.In conclusion, the findings demonstrate that once daily generalized seizures can exert significant effects on heart rate rhythms. Respective alterations in patients would be of relevance for patient counselling and therapeutic management. Occurrence of biphasic bradycardia associated with seizure induction suggests that the kindling model is suitable to study the consequences and the prevention of ictal bradycardia, which may pose patients at risk for sudden unexpected death.

Diurnal rhythm of fetal heart rate in third trimester of pregnancy

Objective: To investigate the diurnal rhythms of fetal heart rate in third trimester of pregnancy. Methods: From June 2014 and October 2017, 97 cases of low-risk pregnancy women who received antenatal care and deliveried in Peking University Third Hospital were collected. Totally 130 cases of fetal heart rate and maternal holter monitoring data were analyzed. All cases were singleton pregnancy, cephalic position and had normal perinatal outcome. They were divided into three groups based on gestational age, 29 cases (22.3%,29/130) in pregnancy 28-33(+6) weeks, 37 cases (28.5%,37/130) in 34-36(+6) weeks, and 64 cases (49.2%, 64/130) in 37-40(+6) weeks. Fetal heart baseline (FHB) , fetal heart baseline variation (FHBV) , fetal heart rate acceleration area and maternal heart rate were acquired by computer, their diurnal rhythms and the differences among three groups were analyzed. Results: FHB、FHBV、fetal heart rate acceleration area and maternal heart rate all presented diurnal rhythms. (1) FHB rose in daytime and decreased at night with the minimum value at 2:00-5:00, and didn't decline further at night with the advancing of gestational age (P=0.548). (2) FHBV was similar to FHB, which rose in daytime and decreased at night, but declined smaller at night with the advancing of gestational age, especially after 37 weeks (P<0.01). (3) Fetal heart rate acceleration area reduced in daytime and enlarged at night, and enlarged more with the advancing of gestational age. (4) The diurnal rhythm of maternal heart rate was consistent with fetal heart rate. FHB lagged behind maternal heart rate for 1-2 hours when declining to the nocturnal nadir but been basically in sync with maternal heart rate when recovered. Conclusion: The basic characteristics of fetal heart rate in normal pregnancy exist obviously diurnal rhythms, and change in different trends with the advancing of gestational age.

Determination of acute toxicity of “Bendamin” drug in laboratory animals

The study of acute toxicity is a mandatory stage in the investigation of new drugs, which allows assessing the health of substances for health in the short-term and determining the class of toxicity and breadth of therapeutic action. Therefore, at the first stage of the study, the acute toxicity of Bendamin Cardiomatography was studied, in particular the determination of maximum tolerant, toxic and intermittent lethal doses for laboratory animals. The acute toxicity of Bendamin was determined in two stages: indicative and expanded experiments. In the indicative trial, the drug was administered intragastrically at doses of 50, 500 and 5000 mg/kg body weight. Three white mice and rats were used for each dose. In an expanded experiment, Bendamin was administered intragastrically at doses of 5000 and 10000 mg/kg body weight. In determining the acute toxicity of Bendamin, the DL50 value could not be determined, indicating a low toxicity of the test substance. Thus, the DL50 drug for intragastric administration to white mice is greater than 5000 mg/kg m. The general condition of animals in the studied groups did not differ from the state of intact animals: coordination of movements and skeletal muscle tone, pain response, tactile and acoustic stimuli were adequate, the frequency of breathing and the rhythm of heart rate were within the normal range. At administration of the preparation in a dose of 5000 mg/kg m. T, an insignificant inhibition was established, which is related to the introduction of a large amount of the drug. In determining the coefficients of the mass of the internal organs of laboratory animals, a slight decrease in the weight coefficient of the liver was found in both mice and in rats. The “Bendamin” drug when administered to white mice and rats in the stomach in the maximum amount does not cause symptoms of poisoning and behavioral abnormalities. According to GOST 12.1.007-76, Bendamin, for intragastric administration, according to the degree of hazard belongs to grade 4 toxicity – low toxicity substances (DL50 more than 10000 mg/kg body weight). In the future, it is planned to investigate the chronic toxicity and cumulative properties of the drug in laboratory animals.

A Novel Diabetic Mouse Model for Real-Time Monitoring of Clock Gene Oscillation and Blood Pressure Circadian Rhythm.

Diabetic patients have an increased prevalence of blood pressure (BP) circadian rhythm disruption, which is associated with an increased risk of target organ damage and detrimental cardiovascular events. Limited information is available regarding the role of clock genes in the disruption of BP circadian rhythm in diabetes due to the lack of a diabetic animal model that allows real-time monitoring of clock gene oscillation. Here, we generated a novel diabetic db/db-mPer2Luc mouse model by crossing type 2 diabetic db/db mice with mPer2Luc knock-in mice. The daily rhythms of BP, heart rate, locomotor activity, and food and water intake were acquired by radiotelemetry or using metabolic chambers. The daily oscillation of mPer2 bioluminescence was recorded by LumiCycle in real-time in tissue explants and using the IVIS system in vivo. Our results show that db/db-mPer2Luc mice are obese, diabetic, and glucose intolerant. The db/db-mPer2Luc mice displayed a compromised BP daily rhythm, which was associated with disrupted daily rhythms in baroreflex sensitivity, locomotor activity, and metabolism, but not heart rate or food and water intake. The phase of the mPer2 daily oscillation was advanced to different extents in the explanted peripheral tissues from db/db-mPer2Luc mice relative to control mice. In contrast, no phase shift was detected in mPer2 daily oscillations in the explanted SCN. Moreover, advanced phase shift of the mPer2 daily oscillation was detected in the liver, kidney and submandibular gland in vivo of db/db-mPer2Luc mice. In conclusion, the diabetic db/db-mPer2Luc mouse is a novel animal model that allows real-time monitoring of mPer2 circadian rhythms ex vivo and in vivo. The results from db/db-mPer2Luc mice suggest that the desynchrony of mPer2 daily oscillation in peripheral tissues contributes to the loss of BP daily oscillation in diabetes.

Вплив 6-місячного лікування різними варіантами антиаритмічної терапії на добову структуру частоти серцевих скорочень і порушень серцевого ритму в пацієнтів з гіпертонічною хворобою та частими нападами фібриляції передсердь

Вплив 6-місячного лікування різними варіантами антиаритмічної терапії на добову структуру частоти серцевих скорочень і порушень серцевого ритму в пацієнтів з гіпертонічною хворобою та частими нападами фібриляції передсердь

Cardiac autonomic activity during simulated shift work.

Shift work leads to adverse health outcomes including increased risk of cardiovascular disease. Heart rate (HR) and heart rate variability (HRV) are measures of cardiac autonomic activity and markers of cardiovascular disease and mortality. To investigate the effects of shift work on cardiac autonomic activity, we assessed the influence of simulated night work on HR and HRV, and dissociated the direct effects of circadian misalignment from those of sleep displacement and altered physical activity patterns. A total of 29 subjects each participated in one of two in-laboratory, simulated shift work studies. In both studies, EKG was continuously monitored via Holter monitors to measure HR and the high frequency (HF) component of HRV (HF-HRV). We found endogenous circadian rhythmicity in HR and HF-HRV. Sleep and waking physical activity, both displaced during simulated night work, had more substantial, and opposite, effects on HR and HF-HRV. Our findings show systematic but complex, interacting effects of time of day, sleep/wake state, and physical activity on cardiac autonomic activity. These effects need to be taken into account when evaluating HR and HRV in shift work settings and when interpreting these measures of cardiac autonomic activity as markers of cardiovascular disease.