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Radiotelemetry measurement of heart rate, blood pressure and locomotory activity of rats in physiological experiment

January 2009

Authors:

Lubos Molcan

Comenius University Bratislava

Zeman Michal

Comenius University Bratislava

Evaluation of physiological traits in freely moving animals represents an innovative approach allowing physiological studies in undisturbed animals without interference with handling and stress. This approach is important in behavioural sciences and research on physiological basis of cardiovascular diseases. Recently, there is only one such system in the world that enables simultaneous measurement of blood pressure, heart rate, body temperature and electroencephalography together with the locomotory activity which was developed by the Data sciences International (st. Paul, Minessota, Usa). In our laboratory we have introduced and validated this system in laboratory rats and hereby present results on blood pressure, heart rate and locomotory activity in rats exposed to stabile light – dark cycles.

Daily profiles of heart rate (A), locomotor activity (B) and blood pressure (C) in a laboratory rat implanted with the sensor TA11PA-C40 (DSI St. Paul, Minnesota, USA). Plots represent outputs from the program Dataquest A.R.T. 4.1 with 8.640 values per 24 h reflecting 1 min averages of measured parameters. Animals were kept at LD 12:12, with lights on from 22:00 till 10:00. The dark bar above graphs represents the dark time period

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Content uploaded by Zeman Michal

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Scientic paper formerly presented

INTRODUCTION

Measurements of physiological variables in

experiments are frequently affected by irregularities

resulting from handling of animals and subsequent

stress. These limitations can be overcome by telemetric

techniques which enable obtaining data without

handling of experimental animals before and during

measurements.

Determination of blood pressure (BP) and heart

rate (HR) is very useful in many types of experiments.

Usually BP is measured by tail-cuff plethysmography on

the tail of laboratory rodents, mainly rats and mice. This

“noninvasive” approach requires handling of animals

and an increase of ambient temperature that result in the

RADIOTELEMETRY MEASUREMENT OF HEART RATE,

BLOOD PRESSURE AND LOCOMOTORY ACTIVITY OF RATS IN

PHYSIOLOGICAL EXPERIMENT

1*11,2

1

2

ABSTRACT

 

undisturbed animals without interference with handling and stress. This approach is important in behavioural sciences and research

on physiological basis of cardiovascular diseases. Recently, there is only one such system in the world that enables simultaneous

measurement of blood pressure, heart rate, body temperature and electroencephalography together with the locomotory activity

 

validated this system in laboratory rats and hereby present results on blood pressure, heart rate and locomotory activity in rats



Key words: 





approach for measuring BP and HR is a radiotelemetric

method. The direct comparison of both methods revealed

that the radiotelemetry provided results about 16 ± 2



al., 1990).

In our experiment we aimed at validation of the

radiotelemetry method for measurement of BP, HR and

locomotory activity. This type of measurement may

provide valuable data especially in continuous long-term-term

experiments. Therefore, we evaluated especially long

term changes of these physiological variables during

circadian rhythms which cannot be assessed by the

noninvasive tail-cuff plethysmography.

*Correspondence:

 



 63

Slovak J. Anim. Sci., 42, 2009, SUPPLEMENT 1: 63-66

ISSN 1337-9984



Original paper Slovak J. Anim. Sci., 42, 2009, SUPPLEMENT 1 : 63-66

MATERIAL AND METHODS

In our experiment we used four mature female

  

    



 

     



administered intramuscularly 600 µl of mixture to 300g



                     

       

   

afterwards radiotelemetry measurements were initiated.

 

activity on freely moving animals we used the

     

       

only one available for this type of measurement. The

system consists from telemetric implants which send

signals to receivers located under the cages in which

animals were individually housed. The receiver converts

measured data and sends them to the matrix connected



that enables recording and storage of results. In our



   

into the abdominal aorta closely to the point of its



        

after the surgery. Data for analysis of circadian rhythms

   

experimental animals exhibited normal behaviour and no

consequences of surgery.

Data were analyzed by the software Dataquest

       

     



RESULTS AND DISCUSSION

       

       

       

intervals. This mode of measurement provided us with

approximately 60,000 records from each animal per

parameter and one day. Representative records of daily



          





values during the light-time were found in a range 60

– 90 mmHg for diastolic BP, with the mean 71.7 ± 0.1



   





and systolic BP, respectively. HR values during the ligh-



         



          





was accompanied by an increase in BP and HR. Mean

locomotory activity during the light-time was 0.8 ± 0.1



up to 3.2 ± 0.1 counts per minute. Measured values

of BP and HR are in ranges reported with telemetric

measurements and are lower as found by noninvasive tail-



become possible to use the telemetric system in different







In all variables we found an increase of values



circadian control of all studied parameters including the

anticipatory increase before the change in the photoperiod.



and locomotory activity we observed rhythmic changes

 

rhythms with period 2-3 hours were much more variable

than the circadian rhythms and their characteristics,

which have not been described well yet.







rhythmic changes with longer periods and demonstrated

     

        

correlated closely between diastolic and systolic BP as



2). Multiple correlations among all studied parameters

       

bioinformatics approach owing to the huge number of

obtained data.

CONCLUSION

     

radiotelemetry techniques for continuous and long term

monitoring of BP, HR and locomotory activity in freely

moving rats. The ranges of obtained values of systolic

and diastolic BP were in the range given in literature.

      

of physiological variables without an interference



Slovak J. Anim. Sci., 42, 2009, SUPPLEMENT 1: 63-66 Original paper

with handling and subsequent stress stimuli of studied



and exchange of batteries in sensors by the manufacturer.

Therefore the use of the system must be carefully

considered.

Fig.1: Daily proles of heart rate (A), locomotor activity (B) and blood pressure (C) in a laboratory rat

implanted with the sensor TA11PA-C40 (DSI St. Paul, Minnesota, USA). Plots represent outputs

from the program Dataquest A.R.T. 4.1 with 8.640 values per 24 h reecting 1 min averages of

measured parameters. Animals were kept at LD 12:12, with lights on from 22:00 till 10:00. The dark

bar above graphs represents the dark time period

Acknowledgements





Original paper Slovak J. Anim. Sci., 42, 2009, SUPPLEMENT 1 : 63-66

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behaviours associated with de-arousal in restricted-fed

Physiology and Behavior



         

Measurement of intraocular pressure by telemetry in

conscious, unrestrained rabbits. Investive Ophthalmology

and Visual Science











Laboratory Animals

  





Fig.2: Daily proles of heart rate (A), locomotor activity (C) and blood pressure (systolic (B) and diastolic

(D)) in the laboratory rat kept in LD 12:12 and monitored by the radiotelemetry system (DSI St.

Paul, Minnesota, USA). Each point at the graph represents a 1-hour mean. Results illustrate a high

correlation between systolic and diastolic BP values and between heart rate and locomotor activity.

The dark bar on the abscissa represents the dark period of the 24 h cycle

Nitric oxide mediated effects of nebivolol on erectile function in rats with heart failure

Article

Full-text available

Jul 2021

Background and objective: Heart failure (HF) is a common complication of cardiovascular disease, which leads to functional cardiac abnormalities. Beta-blockers are commonly used to reduce mortality in HF patients; however, they are associated with an increased risk of erectile dysfunction (ED). Nebivolol is a third-generation beta-blocker with also having a Nitric oxide (NO) releasing effect. NO plays a key role in penile erection. The aim of this study was to investigate the NO-mediated effects of nebivolol on ED in HF. Material and methods: Twenty-four weeks old rats were divided into three groups: sham-operated control (SC), HF-induced control (HFC), and nebivolol-treated (HFNEB). HF was induced by the ligation of the left anterior descending coronary artery. Eight weeks after the ligation, functional, hemodynamic, biologic, and histologic studies were conducted to assess NO-mediated effects of nebivolol. Results: HF rats displayed impaired erectile function represented by decreased intracavernosal/mean arterial pressure ratio (ICP/MAP). Increased nitrosative damage/decreased antioxidant capacity was consistent with decreased endothelial NOS (eNOS) and increased inducible NOS (iNOS) and neuronal NOS (nNOS) immunoreactivity in this group. Nebivolol treated animals were characterized by improved functional capacity, increased antioxidant and decreased oxidant capacity. Prevention of eNOS and an increase in nNOS immunoreactivity was also significant in this group. Conclusion: Our study showed the positive effects of nebivolol on erectile function in HF. NO-mediated mechanisms behind this effect can be summarized as eNOS mediated dilation of the cavernous body and nNOS mediated smooth muscle relaxation. To the best of our knowledge, this study is the first in the literature to discuss all three NOS isoforms in order to explain the NO-mediated effects of nebivolol in ED.

Nitric oxide mediated effects of nebivolol in cardiorenal syndrome

Article

Full-text available

Sep 2019

Objectives: Despite several proposed mechanisms for the pathophysiology of cardiorenal syndrome (CRS), the exact mechanism remains unclear. Nitrosative stress has been argued as a key mechanism recently. Nebivolol is a beta-blocker with nitric oxide (NO)-releasing effect. In the present study, NO-mediated effects of two different treatment regimes of nebivolol in CRS were studied. Materials and methods: Rats were divided into: sham-operated (sham-control), myocardial infarction (MI)-induced, (MI-control) early nebivolol-treated (MI-neb1) and late nebivolol-treated (Mı-neb2) groups. The effects of nebivolol were assessed both in the early and late period of MI by histologic, hemodynamic and biologic studies. Results: Developed MI model was in line with the heart failure with preserved ejection fraction. Focal and total tubular damage findings were observed in MI-control group both in early and late period of MI. In parallel, subclinical functional damage was transformed into chronic renal dysfunction in this group. Increased inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) together with decreased neuronal NOS (nNOS) levels were in parallel with the increased inflammation and nitrosative stress biomarkers. Nebivolol effectively prevented both subclinical and clinical nephropathy. There was no statistical difference between the nebivolol treatment regimes. Conclusion: The beneficial effects of nebivolol were closely related to the reduction of nitrosative damages as well as hemodynamic alterations. The NO-mediated effects were: prevention of nitrosative damage by decreasing iNOS, preservation of nNOS in order to maintain glomerular filtration rate (GFR), and restoration of eNOS in the late period of MI. On contrary to our previous work, early nebivolol administration had a similar effect with delayed administration of nebivolol on CRS.

MONITORING AND EVALUATION OF CIRCADIAN LOCOMOTOR ACTIVITIES IN RODENTS

Article

Full-text available

Jan 2015

Locomotor behaviour is regarded as a fundamental index of general animal activity. Circadian rhythms (CRs) of locomotor activity are one of the most prominent biological rhythms which synchronize to the natural environmental light -dark cycle (LD). The present study aims to develop a reliable and precise setup for long-term recordings of the CRs in laboratory rodents (e.g. rats, hamsters, and mice). The recording setup consists of accessible running wheels (RW) in animal cages. Revolutions of RW were acquired through a circuit supported by either magnetic reed or inf rared (photocell) switch sensors. Data acquisition and analysis were control led through proper software. In a series of experiments, the CRs patterns were successfully recorded under LD, as well as constant darkness (DD) conditions. In summary, the recording setup enabled, with an acceptable precision, to record and analyses the animal 's circadian locomotor activity patterns automatically without upsetting its behaviour pattern. Measurements and analysis of CRs of locomotor activities using this setup could be applied in various research issues such as chronobiological, neuroethological, physiological, and pharmacological studies.Egypt. J. Exp. Biol. (Zool.

Repeated Phase Shifts in the Lighting Regimen Change the Blood Pressure Response to Norepinephrine Stimulation in Rats

Article

Full-text available

Jun 2014
PHYSIOL RES

Disturbed circadian activity of the sympathetic system may be involved in negative consequences of chronodisruption on the cardiovascular system. We studied daily changes in pressure response to adrenergic stimulation in rats exposed to repeated phase advance shifts (PAS) of light/dark (LD) regimen. Blood pressure (BP), heart rate (HR) and locomotor activity was measured by radiotelemetry in normotensive Wistar rats exposed to repeated PAS (three 8-h shifts per week) lasting for 12 weeks. Norepinephrine was administered subcutaneously in the middle of L and D during week 12 of PAS exposure. In the control LD cycle, cardiovascular parameters exhibited significant daily rhythms with expected higher values during D than L phase. Rats exposed to PAS showed disturbed rhythms without a BP and HR increase. Administration of norepinephrine to control rats revealed daily variability in the cardiovascular response with higher stimulation of BP during L than D. This daily pattern of BP response to norepinephrine was diminished in the PAS group. The damped daily variability in pressure response to norepinephrine and augmented response during the light phase of the day suggest that the increased and desynchronised activity of the sympathetic system may worsen responses of the cardiovascular system to load in individuals exposed to irregular LD conditions.

Whole body vibration, an alternative for exercise to improve recovery from surgery?

Article

Full-text available

Sep 2022

Although exercise is usually associated with beneficial effects on physical and mental health, patients recovering from surgery may be hampered to perform active exercise. Whole body vibration (WBV) is suggested a passive alternative for physical training. Aim of the present study was to explore the therapeutic potential of WBV compared to physical exercise during early post-surgery recovery. Male three months old Wistar rats underwent major abdominal surgery. Starting the day after surgery, rats were subjected to either daily WBV or exercise (treadmill running) for 15 consecutive days. Control rats underwent pseudo treatment. During the first week after surgery, effects of interventions were obtained from continuous recording of hemodynamic parameters, body temperature and activity (via an implanted transducer). Behavioral tests were performed during the second post-surgical week to evaluate anxiety-like behavior, short and long-term memory functions, cognitive flexibility and motor performance. Animals were sacrificed 15 days after surgery and brain tissue was collected for analysis of hippocampal neuroinflammation and neurogenesis. Surgery significantly impacted all parameters measured during the first post-surgery week, irrespective of the type of surgery. Effect on cognitive performance was limited to cognitive flexibility; both WBV and exercise prevented the surgery-induced decline. Exercise, but not WBV increased anxiety-like behavior and grip strength. WBV as well as exercise prevented the surgery-induced declined neurogenesis, but surgery-associated hippocampal neuroinflammation was not affected. Our results indicated that active exercise and WBV share similar therapeutic potentials in the prevention of surgery induced decline in cognitive flexibility and hippocampal neurogenesis. In contrast to exercise, WBV did not increase anxiety-like behavior. Since neither intervention affected hippocampal neuroinflammation, other mechanisms and/or brain areas may be involved in the behavioral effects. Taken together, we conclude that WBV may provide a relevant alternative to active exercise during the early stage of post-operative recovery.

Effects of embryo transfer and cryopreservation in rats with inherited stress-induced arterial hypertension

Article

Jan 1997

Embryos of rats with inherited stress-induced arterial hypertension (ISIAH strain) were transferred to normotensive Wistar rats. Cryopreservation of these embryos was used in some trials. Rats developed to term after freezing-thawing of ISIAH embryos and their transfer to Wistar recipients demonstrated a significant decrease in arterial blood pressure (ABP) both in males and females under basal conditions and stress. The effect persisted in subsequent generation obtained from crosses between these animals. In the control series (cryopreservation omitted), transferring of ISIAH embryos to Wistar recipients did cause a decrease; but even ABP increased in offspring. In this experimental series of transferring the unfrozen embryos, ABP of recipient Wistar rats was significantly increased. We have also found behavioral differences between cryopreserved and control rats. Startle reflex was decreased in offspring developed after cryopreservation and embryo transferring of ISIAH rats to Wistar recipients, as compared to initial ISIAH and Wistar rats. Taken together, these experimental data strongly support the hypothesis that embryo freezing and embryo transferring can have delayed consequences for offspring as well as for recipients.

Assisted reproductive technologies and arterial hypertension

Article

Full-text available

Sep 2014

The effects of assisted reproductive technologies on the development of hypertensive phenotype were reviewed. Special attention was paid to the effects of cultivation and transplantation of preimplantation embryos on arterial pressure in individuals developed from these embryos. The analysis of studies performed on the laboratory models (mostly on hypertensive strains of rats) was performed. These data were discussed in the context of application of assisted reproductive technologies in medicine.

The long-term effects of phase advance shifts of photoperiod on cardiovascular parameters as measured by radiotelemetry in rats

Article

Full-text available

Oct 2013
PHYSIOL MEAS

Cardiovascular parameters, such as blood pressure and heart rate, exhibit both circadian and ultradian rhythms which are important for the adequate functioning of the system. For a better understanding of possible negative effects of chronodisruption on the cardiovascular system we studied circadian and ultradian rhythms of blood pressure and heart rate in rats exposed to repeated 8 h phase advance shifts of photoperiod. The experiment lasted 12 weeks, with three shifts per week. Spectral power as a function of frequency for both circadian and harmonic ultradian rhythms was expressed as the circadian-ultradian power ratio. The circadian rhythms of blood pressure, heart rate and locomotor activity were recorded during the control light:dark (LD) regimen with higher values during the D in comparison with the L. Phase advance shifts resulted in a diminished circadian-ultradian power ratio for blood pressure, heart rate and locomotor activity indicating suppressed circadian control of these traits greater in heart rate than blood pressure. In conclusion, rats kept under irregular LD conditions have suppressed circadian control of heart rate, blood pressure and locomotor activity and rely more on an acute response to the LD regime. Their ability to anticipate regular loads can be weakened and in this way chronodisruption can contribute to the pathogenesis of cardiovascular diseases.

Evaluation and applications of radiotelemetry in small laboratory animals1

Article

Full-text available

Jun 2003
PHYSIOL GENOMICS

Radiotelemetry is the "state of the art" for monitoring physiological functions in awake and freely moving laboratory animals, while minimizing stress artifacts. For researchers, especially those in the fields of pharmacology and toxicology, the technique provides a valuable tool for defining the physiological and pathophysiological consequences derived from advances molecular, cellular, and tissue biology and in predicting the effectiveness and safety of new compounds in humans. There is ample evidence that radiotelemetry systems for measuring physiological functions has been sufficiently validated. Today, the technology is an important tool for collection of a growing number of physiological parameters, for contributing to animal welfare (reduction and refinement alternatives), and for reducing overall animal research costs.

Is expression of some behaviours associated with de-arousal in restricted-fed chickens?

Article

Full-text available

Aug 2006
PHYSIOL BEHAV

Broiler breeder chickens show apparently abnormal behaviours when subjected to routine quantitative food restriction during rearing. By using a combination of videorecording and radiotelemetry, this experiment addressed the question of whether such behaviours are associated with de-arousal. In each of 2 years, 3 female chickens had radiotelemetry devices (Data Sciences) implanted surgically at 12 weeks of age, for measuring putative physiological indices of arousal (heart rate, blood pressure, body temperature, telencephalic EEG). Subsequently, when caged individually and moving freely, they were monitored over 2 days when their daily food ration (60 g pellets provided at 0900 h) was all eaten in <10 min. Their behaviour (nine categories) and arousal indices were recorded in every minute during the photoperiod (0700 to 1900 h), using special computer software for videorecording (Noldus) and radiotelemetry (Dataquest LabPRO) analyses. Most time was spent in behaviour categories stand, push bar and feeder directed. Heart rate, blood pressure, body temperature, and relative powers in delta (1-4 Hz) and theta (4-8 Hz) frequency bands of the EEG power spectrum were all highest during feeder directed, whereas heart rate, temperature and delta EEG were all lowest during stand. Judging from significant correlation coefficients between times spent in different behaviours and corresponding physiological variables, across the day, and between ranked mean values of the 6 birds, other trends were also evident. For example, total time spent in all (non-food directed) oral behaviours was related positively to an index of de-arousal (slow wave EEG) and negatively to an index of arousal (heart rate). Collectively, however, these results provide apparently conflicting evidence of both arousal and de-arousal being associated with every behaviour analysed. This conclusion is explicable if abnormal behaviours are related to arousal in a homeostatic way [Savory, C.J., Kostal, L. Temporal patterning of oral stereotypies in restricted-fed fowls: 1. Investigations with a single daily meal. Int. J. Comp. Psychol. 1996, 9:117-139.], being both stimulated by it and reducing it.

Surgical procedure for implanting a radiotelemetry transmitter to monitor ECG, heart rate and body temperature in small Carassius auratus and Carassius auratus gibelio under laboratory conditions

Article

Full-text available

Nov 2006

Radiotelemetry provides an alternative means of obtaining physiological measurements from conscious and freely moving animals, without introducing stress artefacts. A surgical procedure is described for implanting radiotelemetry transmitters to monitor the electrocardiogram (ECG), heart rate (HR) and body temperature (BT) in small goldfish (Carassius auratus; 50-100 g) and Prussian carp (Carassius auratus gibelio; 100 g). This type of transmitter is commonly implanted in freely moving mice. After surgery and a recovery period of 24 h, the ECG, HR and BT were recorded in freely swimming fish within the limitations of the aquarium.

Hyperresponsivity of spontaneously hypertensive rat to indirect measurement of blood pressure

Article

Jul 1978
Am J Physiol

A chronic, indwelling, tail arterial cannula was implated in conscious undisturbed rats for measurement of blood pressure and heart rate and for obtaining blood samples. As an index of sympathetic activity, plasma levels of catecholamines in arterial blood of conscious animals were assayed by a radioenzymatic, paper-chromatographic procedure. Blood pressures of unrestrained spontaneously hypertensive (SHR) rats in their home cages (161 +/- 3/141 +/- 4 mmHg) were not different from those of pentobarbitol-anesthetized, hypertensive animals but were about 25 mmHg lower than awake animals during the restraint required for the tail-cuff procedure. Basal levels of plasma catecholamines in awake, undisturbed or in pentobarbital-anesthetized animals were similar in age-matched SHR and normotensive Wistar-Kyoto (WKY) rats. SHR rats were shown to have greater increase in plasma catecholamines than WKY rats during forced immobilization or restraint for indirect measurement of blood pressure.

A radiotelemetry system for chronic measurement of blood pressure and heart rate in the unrestrained rat validation of the method

Article

Oct 1992
J Pharmacol Toxicol Meth

Chronic measurements of systemic arterial blood pressure and heart rate via a chronically implanted telemetric transmitter in unrestrained rats, was validated in a three-phase study. In the first part, week-to-week variability of systolic, diastolic, and mean arterial pressures, and heart rate was found to be minimal over the course of nine weeks. In the second part, the reproducibility of cardiovascular response to three successive administration of sotalol, an antihypertensive agent, was studied. In the last part, cardiovascular parameters determined by telemetry were compared to those obtained by direct arterial catheterization and showed a good linear correlation between those two methods.

Intra-arterial pressure alterations during tail-cuff blood pressure measurements in normotensive and hypertensive rats

Article

Nov 1990

The heating and restraint inherent to tail-cuff measurement of systolic blood pressure (SBP) in rats may alter SBP and introduce a 'biological' error in its estimation by this technique. This problem was examined in unanesthetized normotensive and hypertensive rats fitted with an arterial catheter. All SBP values recorded in unrestrained rats during a 2 h period were averaged by computer and compared with intra-arterial SBP measurements observed while the rat was being subjected to the tail-cuff procedure. With the latter procedure, SBP was 16 +/- 2 mmHg lower in normotensive rats (P less than 0.001) and 7 +/- 3 mmHg higher in hypertensive rats (P less than 0.05) than when the rats were unrestrained. The effects of heat and restraint, both separately and in combination, on SBP were evaluated during four additional 30-min monitoring periods. In both groups of rats, restraint failed to alter SBP and heat lowered it slightly. The two stimuli, combined, lowered SBP in normotensive rats, but raised it by 12 +/- 2 mmHg in hypertensive rats (P less than 0.01). Thus, tail-cuff SBP measurements represent under- and overestimates in normotensive and hypertensive rats, respectively, since the two groups respond to the procedure in opposite manners.

The influence of restraint on blood pressure in the rat

Article

Dec 1997
J Pharmacol Toxicol Meth

We examined the influence of procedures used in blood pressure measurement on blood pressure and the effects of antihypertensive agents. Subjects were spontaneously hypertensive rats (SHR) and their Wistar/Kyoto (WKY) controls. Blood pressure was recorded by telemetry. Twenty-four h baseline pressure were measured, and the effect of minor handling on blood pressure and heart rate was examined. The influence of restraint such as is used for tail-cuff blood pressures was examined. The effects of three different antihypertensive drugs was also examined in the SHR. In the home-cage environment, the SHRs showed higher systolic blood pressures, but had similar hypertensive responses to minor handling as the WKYs. Both strains had elevated heart rate and blood pressure when restrained in the manner used for tail-cuff readings. The antihypertensive effects of captopril and losartan in the SHR were unchanged when the animals were restrained but the hypotensive effect of hydralazine was greater. These results confirm that significant changes in heart rate and blood pressure can occur as a result of the minor procedures frequently used in blood pressure recording in both SHR and WKY rats. This suggests that telemetry may have significant advantages as a method for continuous blood pressure monitoring. The pharmacological profile of antihypertensive drugs may well be different in animals where telemetry is employed and are not subject to the stresses involved in previous methods of monitoring blood pressure.

Jan 2004

P Zuther

ZUTHeR, P. -leMMeR B. 2004. Chronos-Fit, http://www. ma.uni-heidelberg.de/inst/phar/forschunglemmer.html, 2004.

Radiotelemetry measurement of heart rate, blood pressure and locomotory activity of rats in physiological experiment

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