Telemetric Heart Rate Research Articles

The Usefulness of Outpatient Cardiac Telemetry in Patients with Cryptogenic Stroke.

Introduction: Atrial fibrillation (AF), apart from non-stenotic supracardiac atherosclerosis and neoplastic disease, is the leading cause of cryptogenic stroke, including embolic stroke of un-determined source (ESUS). The aim of our study was to determine the prevalence of AF in ESUS patients based on 30-day telemetric heart rate monitoring initiated within three months after stroke onset. Another aim was to identify factors that increase the likelihood of detecting subsequent AF among ESUS patients. Material and Methods: patients with first-ever stroke classified as per the ESUS definition were eligible for this study. All patients underwent outpatient 30-day telemetric heart rate monitoring. Results: In the period between 2020 and 2022, 145 patients were included. The mean age of all qualified patients was 54; 40% of eligible patients were female. Six patients (4.14%), mostly male patients (4 vs. 2), were diagnosed with AF within the study period. In each case, the diagnosis related to a patient whose stroke occurred in the course of large vessel occlusion. Episodes of AF were detected between day 1 and 25 after starting ECG monitoring. Out of the analyzed parameters that increase the probability of, A.F.; only supraventricular extrasystoles proved to be an independent factor regarding an increased risk of AF [OR 1.046, CI 95% 1.016-1.071, p-value < 0.01]. Conclusions: The use of telemetry heart rhythm monitoring in an outpatient setting can detect AF in 4% of ESUS patients who have undergone prior diagnostic procedures for cardiogenic embolism. Supraventricular extrasystoles significantly increases the likelihood of AF detection in patients with ESUS within three months following stroke. Comorbid coronary artery disease, diabetes and hypertension, rather than a single-factor clinical burden, increase the likelihood of AF detection in older ESUS patients. ESUS in the course of large vessel occlusion is probably associated with an increased likelihood of cardiogenic embolism.

Recovery heart rates as a predictor of race position in race-fit National Hunt racehorses

Prediction of race-fitness using the principles of excess post-exercise oxygen consumption is a potentially valuable applied exercise physiology tool. We hypothesised that horses with a faster heart rate recovery (HRR) after a field test would perform better in their subsequent race. Twenty mature (17 experienced, 3 unraced) National Hunt horses (15 geldings, 5 mares; 6.5±1.1 years; 489±33.5 kg), underwent 34 pre-race 3-interval field exercise tests using telemetric heart rate (HR) and global positioning satellite (GPS) monitoring on a 1,400 m track inclined 32 m. Horses were classified into 3 groups based on post-exercise HRR values obtained 1 minute after peak HR during interval 3 (&gt;140 bpm; unfit; 120-140 bpm; fit-to-race; &lt;120 bpm; fully fit). All horses were from the same yard, under the same management and in their final stage of training (race-ready). Horses were excluded if they were lame or clinically unwell. The outcome measure of finishing in the top third of the field was compared to classification using 2×2 tables (Statcalc, EpiInfo). Peak HR, peak speed and 1 min HRR were 213.4±5.1 bpm, 49.3±1.8 kph and 125.3±15.8 for interval 3. Horses classified as unfit (n=8) did not race. Fully fit and fit-to-race horses competed in 26 jump races (23 hurdles, 3 bumper; 3,200-5,000 m). Fully fit (n=16) horses were more likely to finish in the top 3rd of the field than fit-to-race (n=10) (odds ratio 12.0; 95% confidence interval 1.8-81.7; P=0.01). We conclude that HRR following interval exercise can be used as a predictor of race position in National Hunt racehorses and a useful guide for trainers.

An Evaluation of the Breathing Strategies and Maximum Phonation Time in Musical Theater Performers During Controlled Performance Tasks

Breathing strategies for athletic dancing are quite different from those needed for legato singing. This study considers the respiration data recorded by a telemetric heart rate monitor, mask, and gas analyzer collected from 20 musical theater professionals performing set tasks. Scores were taken of maximum phonation time (MPT), relative oxygen uptake, and heart rate immediately after three tasks: (1) singing only, (2) dancing only, and (3) singing while dancing. Scores were also collected of the ability to sustain unbroken notes immediately before performing and then immediately after each of the above tasks (1), (2), and (3). Vital capacity scores were recorded at the beginning and at the end of the testing schedule. A questionnaire took demographic information and asked questions regarding performer perception, training, and experience. Most were aware of breathing inconsistencies and adjustments related to changes of task and/or direction. (Means) Tidal volume was constant for (1) singing and (2) dancing; MPT reduced by 65.2% for singing while dancing; and minute volumes reduced by 16% but relative oxygen uptake (mL/kg/min) remained unchanged, despite increased heart rates, and when singing while dancing compared with dancing only. The mean MPT dropped from 20.4 seconds to 7.1 seconds (change of 65.2%) between the at rest and postsinging while dancing scores. The likelihood of developing vocal dysfunction (overtime) and the risk of compromising performance aesthetic lead the researchers to the conclusion that further study is required in this area.

The Effects of Acute L-carnitine Supplementation on Endurance Performance of Athletes

This study examined the effect of acute L-carnitine loading on the endurance performance of footballers. Measurements were performed on 26 candidate professional footballers who volunteered to take part in the study. Athletes were given a glass of fruit juice 1 hour before applying L-carnitine with the double-blind method. Then, 12 participants were given 3 g of L-carnitine (LK-3) and the remaining 14 were given 4 g (LK-4). Athletes began the exercise test at a running speed of 8 km·h and then continued at 10 km·h. The speed was increased 1 km·h every 3 minutes, and the test continued until the subject chose to quit. Heart rate was registered using a portable telemetric heart rate monitor during the test. Blood samples were taken from the earlobes of the footballers both before the test and before the speed increase (during the 1-minute interval), and the lactate (La) concentration was measured electroenzymatically. The test was repeated after 1 week as a group of placebos (P-3 and P-4). The result showed that the running speeds corresponding to specific La concentrations were increased, and La and heart rate responses to the running speeds were decreased in both supplemented groups compared with placebos (p ≤ 0.05). A significant reduction in heart rate was found in LK-4 and P-4 (p ≤ 0.05). When the Borg responses to the running speeds were analyzed, a significant difference was found in both supplemented groups (p ≤ 0.05). The results show that 3 or 4 g of L-carnitine taken before physical exercise prolonged exhaustion.

Experimental and husbandry procedures as potential modifiers of the results of phenotyping tests

To maximize the sensitivity of detecting affects of genetic variants in mice, variables have been minimized through the use of inbred mouse lines, by eliminating infectious organisms and controlling environmental variables. However, the impact of standard animal husbandry and experimental procedures on the validity of experimental data is under appreciated. In this study we monitored the impact of these procedures by using parameters that reflect stress and physiological responses to it. Short-term measures included telemetered heart rate and systolic arterial pressure, core body temperature and blood glucose, while longer-term parameters were assessed such as body weight. Male and female C57BL6/NTac mice were subjected to a range of stressors with different perceived severities ranging from repeated blood glucose and core temperature measurement procedures, intra-peritoneal injection and overnight fasting to cage transport and cage changing.Our studies reveal that common husbandry and experimental procedures significantly influence mouse physiology and behaviour. Systolic arterial pressure, heart rate, locomotor activity, core temperature and blood glucose were elevated in response to a range of experimental procedures. Differences between sexes were evident, female mice displayed more sustained cardiovascular responses and locomotor activity than male mice. These results have important implications for the design and implementation of multiple component experiments where the lasting effects of stress from previous tests may modify the outcomes of subsequent ones.

Evaluation of three methodologies to estimate the VO 2max in people of different ages

Aging and gender are factors that affect the variation of physical work capacity. The present paper highlights the importance of the metabolism used by ergonomics to establish the appropriate limits of loads at work. This study compares the aerobic capacity of people from 20 to 71 years old split in 5 different groups. The laboratory experiment tested 33 volunteers (19 women and 14 men). A submaximal step test was used to measure the VO 2 using a portable breath by breath metabolic system and a telemetric heart rate monitor. Three methods to estimate the VO 2max were compared: 1) a direct measurement of VO 2, 2) estimation by heart rate, and 3) a step test method using predetermined charts. Significant difference was encountered among the estimation methods as well as among the age ranges ( F 2,92 = 6.43, p < 0.05 y F 4,92 = 7.18, p < 0.05 respectively). The method of direct measurement and the method of predetermined charts were different for the estimation of the VO 2max with a confidence level of 95%. The method of predetermined charts is better adapted for males and people younger than 30 years. The estimation through non invasive heart rate apparatus was a good appraiser of the maximal oxygen consumption considering both genders and all the age groups.

Milestones in Progression of Primary Pneumonic Plague in Cynomolgus Macaques

Vaccines against primary pneumonic plague, a potential bioweapon, must be tested for efficacy in well-characterized nonhuman primate models. Telemetered cynomolgus macaques (Macaca fascicularis) were challenged by the aerosol route with doses equivalent to approximately 100 50% effective doses of Yersinia pestis strain CO92 and necropsied at 24-h intervals postexposure (p.e.). Data for telemetered heart rates, respiratory rates, and increases in the temperature greater than the diurnal baseline values identified the onset of the systemic response at 55 to 60 h p.e. in all animals observed for at least 70 h p.e. Bacteremia was detected at 72 h p.e. by a Yersinia 16S rRNA-specific quantitative reverse transcription-PCR and was detected later by the culture method at the time of moribund necropsy. By 72 h p.e. multilobar pneumonia with diffuse septal inflammation consistent with early bacteremia was established, and all lung tissues had a high bacterial burden. The levels of cytokines or chemokines in serum were not significantly elevated at any time, and only the interleukin-1beta, CCL2, and CCL3 levels were elevated in lung tissue. Inhalational plague in the cynomolgus macaque inoculated by the aerosol route produces most clinical features of the human disease, and in addition the disease progression mimics the disease progression from the anti-inflammatory phase to the proinflammatory phase described for the murine model. Defined milestones of disease progression, particularly the onset of fever, tachypnea, and bacteremia, should be useful for evaluating the efficacy of candidate vaccines.

Evaluation Of Telemetric Heart Rate Monitors During Treadmill Exercise

Measurement of heart rate during exercise is extremely important to the understanding of energy expenditure and physical training of the cardiovascular system. Accurate measurements of heart rate have been encumbered by the size of the monitor, difficulty of use, and the reliability of the measurement devices in the presence of movement artifacts. There is interest in developing accurate, small, non-intrusive monitors for use in exercise regimens where direct wire leads cannot be tolerated, where ease of use is critical, and where movements may give rise to artifacts. PURPOSE This study evaluated three telemetric heart rate monitors, the Actiheart [AH] (Mini Mitter Co., Inc., Bend, OR), Polar #S-810i and XR [PL](Polar, Finland), and XHR VitalSense Heart Rate sensor [VS] (Mini Mitter Co., Inc., Bend, OR). METHODS All heart Rate sensors were compared to the Welch-Allyn Atlas (6200 Series) stationary heart rate monitor. Six (6) volunteers, three men and three women, wore the four sensors, placed in specific locations on the chest. All sensors were attached to 3M Red Dot electrodes in a specific placement to maximize the electrical signal and placement was in a random order so as not to bias the data due to placement alone. Data were recorded as beats per minute in fifteen-second epochs. Subjects rested for ten minutes to determine resting heart rate and then all subjects completed a modified Bruce protocol treadmill test (3 minutes 1.7 mph, 0% slope; 3 minutes 2.5 MPH, 3% Slope; 3 minutes 3.4 MPH, 6%; and 3 minutes 4.2 mph, 9% slope). Following the exercise protocol subjects were allowed to rest until heart rate returned to resting values. RESULTS All three of the devices demonstrated a similar specificity, 0.97, 0.98, 0.97, for AH, PL, and VS respectively. However, PL demonstrated a significantly, p < 0.01, reduced sensitivity (0.85) as compared to AH (0.98) and VS (0.98). In addition, PL also showed a significantly greater number of false positive readings (15.2%) as compared to AH (2.34%) and VS (2.5%). The correlation between PL and the Atlas standard was significantly worse during exercise as compared to rest. CONCLUSION The results reported here indicate that there is a need for additional studies to validate accurate measurements of heart rate in exercising subjects, particularly when the exercise is rigorous. Supported by Mini Mitter, CO., Inc and U.S. Army DAMD17-01-C-0022

Evaluation Of Telemetric Heart Rate Monitors During Treadmill Exercise

Evaluation Of Telemetric Heart Rate Monitors During Treadmill Exercise

Individually Coded Telemetry: a Tool for Studying Heart Rate and Behaviour in Reindeer Calves

The aim of the study was to test the performance of a silver wire modified version of the coded telemetric heart rate monitor Polar Vantage NV™ (PVNV) and to measure heart rate (HR) in a group of captive reindeer calves during different behaviour. The technical performance of PVNV HR monitors was tested in cold conditions (-30°C) using a pulse generator and the correlation between generated pulse and PVNV values was high (r = 0.9957). The accuracy was tested by comparing the HR obtained with the PVNV monitor with the standard ECG, and the correlation was significant (r = 0.9965). Both circadian HR and HR related to behavioural pattern were recorded. A circadian rhythm was observed in the HR in reindeer with a minimum during night and early morning hours and maximum at noon and during the afternoon, the average HR of the reindeer calves studied being 42.5 beats/min in February. The behaviour was recorded by focal individual observations and the data was synchronized with the output of the HR monitors. Running differed from all other behavioural categories in HR. Inter-individual differences were seen expressing individual responses to external and internal stimuli. The silver wire modified Polar Vantage NV™ provides a suitable and reliable tool for measuring heart rate in reindeer, also in natural conditions.

In vivo neurotransmitter release in the locus coeruleus--effects of hyperforin, inescapable shock and fear.

Hyperforin, the main antidepressant constituent of Hypericum perforatum, influences the extracellular concentrations of transmitters in vitro and in vivo. In vivo experiments have shown that hyperforin enhances the extracellular concentrations of dopamine, norepinephrine, serotonin and glutamate in the locus coeruleus. Hyperforin-free Hypericum extract also elevates the extracellular concentrations of dopamine and norepinephrine in the locus coeruleus, but, in contrast to hyperforin, the extracellular concentration of serotonin is diminished. The differing profiles of hyperforin and hyperforin-free Hypericum extract on the extracellular transmitter concentrations point to the presence of an additional biologically active compound in Hypericum perforatum. Inescapable shock increases the release of monoamines and several amino acids, as well as motility, blood pressure and heart rate. Conditioned fear, similar to hyperforin-free Hypericum extract, decreases the release of serotonin in the locus coeruleus. Conditioned fear also leads to tachycardia. The latter finding shows that telemetric heart rate recording is a good index for conditioned fear. In vivo findings confirm the idea that the anti-depressive properties of Hypericum extract and hyperforin result from increases in extracellular neurotransmitter concentrations. Since hyperforin-free extract, like conditioned fear, reduces the extracellular concentration of serotonin, hyperforin may be more beneficial than Hypericum extract in the treatment of depressive disorders.

A Non-Invasive System for Remotely Monitoring Heart Rate in Free-Ranging Ungulates

AbstractA new, external non-invasive telemetric heart rate (HR) monitoring system was evaluated on eight wapiti, Cervus elaphus canadensis, yearlings in July and August 1996. The assembly consisted of a leather girth strap, onto which a HR transmitter and a customized carriage bolt electrode system were fixed. To prevent the girth strap from rotating on the animal, it was secured with adjustable nylon straps extending anteriorly between the forelegs up to an adjustable neck collar. In preliminary testing, audible tones were received during 99 per cent (n = 902) of the 15s intervals when the animals were active, but only during 33 per cent (n = 156) when they were bedded. After 2 weeks, the equipment remained functional (and was removed); the effective signal range was consistently beyond 500m. This HR monitoring system is easy to attach externally, obviates complications from surgery, and provides coverage over an extended range.The monitoring system offers a reliable, humane and inexpensive method for short-term measurement of HR in captive or wild ungulates. Further tests may reveal a potential for long-term application. The ability to measure physiological responses under different management regimes can aid ungulate farmers in selecting optimal herd sizes and social structures for their animals; and in developing superior housing, enclosure designs, handling and transport methods. This improves the animals’ welfare, and ultimately leads to an increase in animal growth and herd productivity. In addition, information about heart rates can help wildlife managers to improve their management strategies, by gaining an understanding of the energy expenditure associated with various activities and environmental influences.

MAXIMAL HEART RATE PREDICTION FROM THE UKK 2km WALK TEST RESULTS

67 The UKK 2km Walk Test was previously developed to predict maximal aerobic power (VO2max) in healthy adults. In order to improve exercise prescription from the Walk Test results we studied the possibility of developing a regression equation to predict maximal heart rate (HRmax) from the Walk Test results in 109 (53 men, 56 women) healthy, Finnish adults. Their mean ± SD age was 41,3 ± 4,9 years and BMI 25,2 ± 2,9 kg/m2. In a maximal graded treadmill test the directly measured VO2max was 40,2 ±5,6 ml·kg-1·min-1 and HRmax 188±10 bpm. The subjects performed the submaximal UKK 2km Walk Test on an indoor track. Walking heart rate (HR2km) was registered by a telemetric heart rate monitor (Polar Electro Oy, Finland). Oxygen consumption corresponding to the walking speed (VO2walk) was calculated based on a formula by Walt & Wyndham (1973). A fractional VO2max (VO2%) for the Walk Test was assessed as VO2% = VO2walk/VO2max·100. A multiple regression analysis yielded the following formula for predicted HRmax: 147,47 + 0,493(HR2km) - 0,509(VO2%). Reported standard error for the ACSM HRmax formula (220-age) is ±15 bpm. In the present study 93% of the subjects were within ± 14 bpm of the measured HRmax, with a SEE of 8 bpm, while the ACSM formula yielded only 71% of the subjects within that range. A total error (E) was 14 bpm. Ninety-five and 78% of the subjects were within ±8 bpm of the measured submaximal 60 and 90% HR levels, respectively. In conclusion, the developed formula provides an accurate method for maximal and submaximal target heart rate predictions for healthy adults. The validity of the developed prediction equation needs to be studied further in overweight and highly trained adults of different age.

Heart rate monitors: State of the art

Heart rate is a useful indicator of physiological adaptation and intensity of effort. Therefore, heart rate monitoring is an important component of cardiovascular fitness assessment and training programmes. The electrocardiogram (ECG) and Holter monitoring devices are accurate, but they are not appropriate for use in field settings due to cost, size and complexity of operation. Lightweight telemetric heart rate monitors equipped with conventional electrodes have been available since 1983 and have been shown to be accurate and valid tools for heart rate monitoring and registering in the field. Polar Electro Oy has been at the forefront of ambulatory heart rate monitor technology for 15 years. This paper reviews the development of Polar heart rate monitors and their measurement accuracy compared to Holter ECG devices at rest and during exercise, both in adults and in children.

Real-time non-invasive measurement of heart rate inworking dogs: a technique with potential applications in the objective assessment of welfare problems

The Polar Sport Tester (Polar Electro OY) is a telemetric heart rate monitor designed for use in humans. Its usefulness as a monitor during training of guide dogs is assessed in this paper. Heart rates from six representative dogs at a similar stage of early training were recorded at 5-s intervals during a 15-20 min work session. The dogs were F1 Labrador Retriever x Golden Retrievers. They were chosen if their behaviour could be clearly categorized by their experienced trainers as either 'calm/non-stress prone' (Type A) or 'excitable/stress prone' (Type B) during work. Verbal recordings were made of environmental cues and behavioural responses in each dog. Variability in heart rate was significantly related to a subject's described temperament.

Regional changes in c-fos expression in the basal forebrain and brainstem during adaptation to repeated stress: correlations with cardiovascular, hypothermic and endocrine responses.

Acute stress is known to evoke a discrete pattern of c-fos expression in the brain. The work reported here shows that this pattern is modified in regionally specific ways following repeated stress, and that this can be correlated with changes in telemetered heart rate, core temperature and corticosterone output that occur during adaptation. Intact male rats were restrained for 60 min daily for one or 10 days. Stress-induced tachycardia was maximal 10 min following the onset of restraint, and decreased thereafter. The peak value was not altered by repeated restraint, but levels fell towards baseline values more rapidly with increasing bouts of stress. Core temperature showed marked reduction during the first 10 min of the initial stress, followed by a minor (and not very consistent) overshoot during the remainder of the stress period. In contrast to heart rate, stress-induced hypothermia did not alter during repeated restraint. Corticosterone was raised dramatically immediately following the first 60-min session of restraint, and this was attenuated by repeated stress. Sixty minutes after the end of the first stress session, there was pronounced c-fos expression in the lateral septum, lateral preoptic area, lateral hypothalamic area, all divisions of the hypothalamic paraventricular nucleus, the medial (but not central) amygdala, the locus ceruleus and a brainstem structure (thought to be Barrington's nucleus), compared to rats transferred to the testing room but not restrained. Sixty minutes after the 10th stress session, c-fos expression was markedly decreased in some of these areas compared with the pattern observed after the first stress, especially in the paraventricular nucleus (dorsal and medial parvicellular regions) and in medial amygdala. However, all other areas measured demonstrated a sustained response even after repeated stress. There were no significant differences in c-fos expression in rats repeatedly transferred to the testing room (but not stressed) compared to singly transferred counterparts. These results show that both neuronal and physiological responses adapt to a repeated stress, but that in both cases this has highly specific components. It seems likely that adaptive changes in c-fos expression are associated with those in some features of autonomic and endocrine reactions. It is noteworthy that there is evidence that the lateral septum, in which c-fos expression did not diminish after repeated stress, may be involved in temperature control, whereas the paraventricular nucleus, in which c-fos did alter, has been linked with both cardiac and corticoid regulation.

Effect of Vasopressin on Circadian Heart Rate, Body Temperature, and Activity

Male, vasopressin-containing, Long-Evans (LE) and vasopressin-deficient, Brattleboro (DI) rats were maintained in individual cages while telemetered heart rate (HR), core body temperature (BT) and activity level (AC) data were collected. The rats were exposed to a 12:12 light-dark cycle with room temperature maintained at 23±1°C. A 1h feeding period was initiated 1h after the beginning of the dark cycle and another 1h feeding period commenced 7h into the dark cycle. While patterns of circadian rhythms of HR, BT, and AC were similar between DI and LE rats, there were significant differences in all three variables. When compared to LE animals, DI animals had a significantly: 1) slower HR throughout the circadian cycle; 2) lower BT throughout most of the circadian cycle; and 3) higher AC levels at the onset of the dark cycle. Results show that vasopressin plays a modulatory role in circadian rhythms of HR, BT, and AC.

Heart rate as an indicator of metabolic rate and activity in adult Atlantic salmon, Salmo salar

Telemetered heart rate (fH) was examined as an indicator of activity and oxygen consumption rate (VO2) in adult, cultivated, Atlantic salmon, Salmo salar L. Heart rate was measured during sustained swimming in a flume for six fish at 10° C [mean weight, 1114 g; mean fork length (f. l.), 50·6 cm] and seven fish at 15° C (mean weight, 1119 g; mean f. l., 50·7 cm) at speeds of up to 2·2 body lengths/s. Semi–logarithmic relationships between heart rate and swimming speed were obtained at both temperatures. Spontaneously swimming fish in still water exhibited characteristic heart rate increases associated with activity. Heart rate and Vo2 were monitored simultaneously in a 575–1 circular respirometer for six fish (three male, three female) at 4° C (mean weight, 1804 g; mean F. L., 62· cm) and six fish (three male, three female) at 10° C (mean weight, 2045 g; mean f. l., 63·2 cm) during spontaneous but unquantified activity. Linear regressions were obtained by transforming data for both fH and Vo2 to log values. At each temperature, slopes of the regressions between fH and Vo2 for individual fishes were not significantly different, but in some cases elevations were. All differences in elevation were between male and female fish. There were no significant differences in regression slope or elevation for fish of the same sex at the two temperatures and so regressions were calculated for the sexes, pooling data from 4 and 10° C. There was no significant difference in the mean ± S. D. Vo2 between the sexes at 4° C (male, 66·0 ± 59·6 mgO2 kg−1 h−1; female, 88·0 ± 60·1 mgO2 kg−1 h−1) or 10° C (male, 166·2 ± 115·4 mgO2 kg−1 h−1; female, 169·2 ± 111–1 mgO2 kg−1h−1). Resting Vo2 (x̄± s. d.) at 4°C was 36·7 ± 8.4 mgO2 kg−1 h−1, and 10° C was 72·8 ± 11·9 mgO2 kg−1 h−1. Maximum Vo2 (x̄± S. D.) at 4° C was 250·6 ± 40·2 mgO2 kg−1 h−1, and at 10° C was 423·6 ± 25·2 mgO2 kg−1 h−1. Heart rate appears to be a useful indicator of metabolic rate over the temperature range examined, for the cultivated fish studied, but it is possible that the relationship for wild fish may differ.

Long-term impairment of autonomic circadian rhythms after brief intermittent social stress

This experiment was designed to examine the short- and long-term behavioral, cardiovascular, and thermoregulatory responses to brief intermittent agonistic confrontations in rats. The experimental procedure involves resident-intruder confrontations consisting of a 10-min period during which both animals are separated in the home cage of the resident, followed by a brief physical encounter leading to defeat of the intruder and a 10-min period, when the intruder was alone in the home cage of the resident. These 30-min-long confrontations were repeated on 5 consecutive days. Before the first confrontation with a resident, an intruder rat's telemetered heart rate and core temperature show a stable circadian rhythm that is entrained by the light cycle. Acutely, the confrontations produce immediate and large tachycardia and hyperthermia in intruders. A decrease in amplitude of the circadian rhythms for heart rate and core temperature, as detected by cosinor analysis, persists for at least 10 days after the last of five daily brief confrontations with the resident. The defensive upright posture is nearly absent during the first exploration of the resident's home cage, but is displayed by the intruder for one-third of the available time before and after the fifth defeat. Intermittent brief social stress is sufficient to induce profound changes in defensive behavior and long-lasting depression of circadian rhythmicity that persist for weeks.

Telemetered Heart Rate as a Measure of Metabolic Rate in the Lemon Shark, Negaprion brevirostris

SMITH, C. K. 1990. Effects of variation in body size on intraspecific competition among larval salamanders. Ecology 71:1777-1788. SNEDECOR, G. W., AND W. G. COCHRAN. 1980. Statistical methods. Iowa State Univ. Press, Ames. STAMPS, J. A. 1977. The relationship between resource competition, risk, and aggression in a tropical territorial lizard. Ecology 58:349-358. VERRELL, P. A. 1989. The sexual strategies of natural populations of newts and salamanders. Herpetologica 45:265-282. WALLS, S. C. 1990. Interference competition in postmetamorphic salamanders: interspecific differences in aggression by coexisting species. Ecology 71:307314.