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

Guiol, Chantal; Ledoussal, Clara; Surgé, Jean-Marc

doi:10.1016/1056-8719(92)90054-5

Cited by 56 publications

(20 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We found that TCP tended to induce a small pressor response in control rats (by 16Ϯ7 and 22Ϯ10 on days 6 and 12, respectively), similar to what others have reported. 4,10 This trend, however, did not reach statistical significance in our study, likely because the increases in SBP were not only less pronounced, but also less consistent than in the Ang II-treated rats.…”

Section: Discussioncontrasting

confidence: 49%

Low-Dose Angiotensin II Enhances Pressor Responses Without Causing Sustained Hypertension

et al. 2003

View full text Add to dashboard Cite

Abstract-Subpressor doses of angiotensin II (SP-Ang II) cause a slow increase in blood pressure in rats as assessed by tail cuff plethysmography (TCP), reflecting either sustained hypertension or an exaggerated pressor response to diverse stimuli. We examined whether subpressor doses of Ang II enhance blood pressure responses to simple stress (handling of trained rats for TCP). We implanted telemetry in Sprague-Dawley rats. After 10 days of recovery and TCP training, we implanted osmotic minipumps with either SP-Ang II (50 ng/kg per minute) or vehicle, and then measured systolic blood pressure continuously in unrestrained rats for 13 days. We also recorded telemetry readings while obtaining TCP measurements every 2 days. SP-Ang II increased blood pressure from 134Ϯ19 to 159Ϯ22 mm Hg by TCP, which matched the simultaneous telemetry readings of 131Ϯ20 to 154Ϯ25 mm Hg. In contrast, SP-Ang II did not change the blood pressure in the unrestrained rats (measured with continuous telemetry: 124Ϯ2 versus 127Ϯ1 mm Hg). The blood pressure in the control rats did not change in the unrestrained state (125Ϯ3 versus 128Ϯ5 mm Hg on days 0 and 12, respectively), and only slightly increased during TCP (11Ϯ5 and 6Ϯ4 mm Hg by TCP and simultaneous telemetry, respectively; PϭNS). In summary, SP-Ang II, although unable to provoke sustained hypertension, nonetheless magnifies the pressor response to otherwise trivial stimuli. We speculate that even modestly elevated Ang II levels may contribute to hypertensive complications because such levels promote the punctuation of an apparent normotensive state by episodic hypertension occasioned by seemingly innocuous stimuli. Key Words: angiotensin II, Ⅲ hypertension, experimental Ⅲ blood pressure Ⅲ vasculature C hronically infusing a subpressor dose of angiotensin II (SP-Ang II) increases blood pressure after several days. 1-2 This hypertensive response, known as the slow pressor response to Ang II, has been shown by many laboratories including our own. 3 Most have studied this phenomenon using tail cuff plethysmography (TCP) to measure blood pressure in the conscious animals. 1,2,3 Although this technique is very valuable, it does have certain limitations. For instance, it does not allow for continuous monitoring of blood pressure. In addition, the procedure is somewhat cumbersome and involves warming the rats, placing them in restraining cages, and then inflating the tail cuff; all of these steps have been shown to induce a stress response in trained normotensive animals, which consequently may alter the blood pressure. 4,5 Recently, a radiotelemetric recording system has been developed, which permits long-term continuous monitoring of blood pressure in animals without the stress of heating, handling, or restraining. 6,7 Thus, we incorporated this new technology in our laboratory to enhance our blood pressure monitoring during SP-Ang II-induced hypertension (HTN). Using this methodology, we initially attempted to reproduce our previous findings. However, we were surprised to find that 5 ng/k...

show abstract

Section: Discussioncontrasting

confidence: 49%

Low-Dose Angiotensin II Enhances Pressor Responses Without Causing Sustained Hypertension

et al. 2003

View full text Add to dashboard Cite

show abstract

“…Core temperature 7,8 and HR, 9 two indices of successful heat acclimation, are both increased by the handling and restraint usually required to measure these variables in the rat. Further, some of the specific pathogen‐free rats currently supplied by breeders may have an exaggerated hyperthermic response to experimental stress 10 .…”

Section: Introductionmentioning

confidence: 99%

Telemetry Augments the Validity of the Rat as a Model for Heat Acclimation

Matthew

1997

Annals of the New York Academy of Sciences

View full text Add to dashboard Cite

Repeated exposure to heat stress results in physiological adaptations which increase tolerance to heat stress. Core temperature (Tc) and heart rate (HR), two indices of successful heat acclimation, are both increased by the handling and restraint usually required to measure these variables in the rat. This study compares measurement of these variables in telemetry- and nontelemetry-equipped heat-acclimated rats. Four groups of male Sprague-Dawley rats were used: CAC (24, control for acclimated), HAC (24, heat acclimated), TCAC (3, telemetry implanted control for acclimation), and THAC (3, telemetry implanted, heat acclimated). The CAC and TCAC rats were maintained at 26 degrees C for 2 weeks; HAC and THAC groups were maintained at 32-33 degrees C for 2 weeks. The telemetry rats were surgically implanted with transmitters which measured activity, temperature, blood pressure (BP), and ECG. Following acclimation, the rats were subjected to a heat-stress test as follows: animals were placed in a chamber maintained at 41.5 degrees C until a Tc of 41.5 degrees C was reached, when the animals were removed to a 26 degrees C chamber to recover. The Tc of the CAC and HAC rats was manually measured with a rectal probe every 15 min. The TCAC and THAC rats had Tc, HR, and BP monitored electronically every 2.5 min from 30 min prior to heat stress through 30 min after heat. The THAC rats maintained lower Tc, HR, and BP than the TCAC rats throughout the heat stress. The CAC and HAC rats had higher Tc and slower rates of cooling after heat than either of the telemetry groups. Simultaneous measurement of HR, BP, and Tc has not previously been reported in unrestrained heat-acclimated rats. Measurement of these variables without the confounding effects of restraint or handling has increased the validity of the rat as a model for human heat acclimation.

show abstract

“…One problem might have been the use of catheters, harnesses, and tethers, which by themselves can greatly influence behavioral responses. To record behavioral and cardiovascular responses without the use of indwelling cannulae, in the present study we used radiotelemetry and small implantable radiotransmitters allowing the rats to be truly freely moving and unrestrained~Brockway, Mills, & Azar, 1991;Guiol, Ledoussal, & Surgé, 1992;Van den Buuse, 1994!. In the present study, we thus set out to characterize the open field test in rats as a stimulus model to investigate cardiovascular responses to psychological stress. We used automated methodology, including radiotelemetric assessment of blood pressure and heart rate, and video-tracking analysis of exploratory locomotor behavior.…”

Section: Descriptorsmentioning

confidence: 99%

Blood pressure, heart rate, and behavioral responses to psychological “novelty” stress in freely moving rats

et al. 2001

View full text Add to dashboard Cite

We developed a new model of psychological "open-field" stress in freely moving rats. Blood pressure and heart rate of the rats were measured by radiotelemetry and behavior analyzed by video tracking software. Open-field exposure induced marked increases in blood pressure and heart rate. Repeated daily exposure induced pressor responses that were slightly higher on Day 4 when compared to Day 1. Pretreatment with the b 1 -adrenoceptor antagonist atenolol inhibited the tachycardia whereas the ganglion blocker pentolinium inhibited the pressor response, indicating involvement of the sympathetic nervous system. Pretreatment with diazepam prevented the novelty stress-induced pressor response and reduced the tachycardia. These results show that the psychological stress of exposing rats to an open field induces marked cardiovascular effects that are mediated by sympathetic hyperactivity. This model is unique in that it focuses on psychological stress and allows concomitant measurement of blood pressure, heart rate, and behavior in freely moving rats.

show abstract

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

Cited by 56 publications

References 6 publications

Low-Dose Angiotensin II Enhances Pressor Responses Without Causing Sustained Hypertension

Low-Dose Angiotensin II Enhances Pressor Responses Without Causing Sustained Hypertension

Telemetry Augments the Validity of the Rat as a Model for Heat Acclimation

Blood pressure, heart rate, and behavioral responses to psychological “novelty” stress in freely moving rats

Contact Info

Product

Resources

About