The effects of triiodothyronine (T3) on heart rate, temperature and ECG measured with telemetry in freely moving mice

Unilateral microinjection of neuropeptide Y (NPY) into the posterior hypothalamic nucleus was previously found to evoke a sympathoexcitatory-mediated increase in mean arterial pressure (MAP) in urethan-anesthetized rats. In this study, the effect of unilateral injection of NPY into the posterior hypothalamic nucleus on the cardiovascular system of conscious, freely moving rats was determined. Microinjection of NPY (0.2-2.4 nmol) or the cholinergic agonist carbachol (0.5-5.5 nmol) resulted in concentration-dependent increases in MAP. Pretreatment of animals with 7.5 mg/kg iv of the ganglionic blocker pentolinium resulted in a blockade of the increase in MAP evoked by microinjection of NPY (2.4 nmol) or carbachol (3.3 nmol). Despite their similarity of effects on MAP, NPY and carbachol evoked different changes in heart rate. NPY increased heart rate, whereas carbachol evoked a biphasic change in heart rate that consisted of an initial increase followed by a decrease. In addition, carbachol caused increases in both hindquarter and mesenteric vascular resistances, whereas NPY caused a short-lasting increase in mesenteric resistance and a tendency toward an increase in hindquarter resistance. Both NPY and carbachol increased total peripheral resistance while NPY decreased stroke volume. Cardiac output was not significantly affected by either NPY or carbachol, although NPY had a tendency to decrease cardiac output. These results suggest that microinjection of NPY or carbachol into the posterior hypothalamic nucleus of conscious rats evokes an increase in MAP primarily as a result of sympathoexcitation and that NPY and carbachol selectively affect autonomic nervous system control of the cardiovascular system.

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Chronic heart rate reduction remodels ion channel transcripts in the mouse sinoatrial node but not in the ventricle

Physiological Genomics ◽

10.1152/physiolgenomics.00161.2005 ◽

2006 ◽

Vol 24 (1) ◽

pp. 4-12 ◽

Cited By ~ 30

Author(s):

Anne-Laure Leoni ◽

Céline Marionneau ◽

Sophie Demolombe ◽

Sabrina Le Bouter ◽

Matteo E. Mangoni ◽

...

Keyword(s):

Heart Rate ◽

Ion Channel ◽

Clustering Analysis ◽

Connexin 43 ◽

Sinoatrial Node ◽

Rt Pcr ◽

Cardiac Electrical Activity ◽

Channel Expression ◽

Freely Moving ◽

Α Subunits

We investigated the effects of chronic and moderate heart rate (HR) reduction on ion channel expression in the mouse sinoatrial node (SAN) and ventricle. Ten-week-old male C57BL/6 mice were treated twice daily with either vehicle or ivabradine at 5 mg/kg given orally during 3 wk. The effects of HR reduction on cardiac electrical activity were investigated in anesthetized mice with serial ECGs and in freely moving mice with telemetric recordings. With the use of high-throughput real-time RT-PCR, the expression of 68 ion channel subunits was evaluated in the SAN and ventricle at the end of the treatment period. In conscious mice, ivabradine induced a mean 16% HR reduction over a 24-h period that was sustained over the 3-wk administration. Other ECG parameters were not modified. Two-way hierarchical clustering analysis of gene expression revealed a separation of ventricles from SANs but no discrimination between treated and untreated ventricles, indicating that HR reduction per se induced limited remodeling in this tissue. In contrast, SAN samples clustered in two groups depending on the treatment. In the SAN from ivabradine-treated mice, the expression of nine ion channel subunits, including Navβ1 (−25%), Cav3.1 (−29%), Kir6.1 (−28%), Kvβ2 (−41%), and Kvβ3 (−30%), was significantly decreased. Eight genes were significantly upregulated, including K+ channel α-subunits (Kv1.1, +30%; Kir2.1, +29%; Kir3.1, +41%), hyperpolarization-activated cation channels (HCN2, +24%; HCN4, +52%), and connexin 43 (+26%). We conclude that reducing HR induces a complex remodeling of ion channel expression in the SAN but has little impact on ion channel transcripts in the ventricle.

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Effects of prophylactic antibiotic-treatment on post-surgical recovery following intraperitoneal bio-logger implantation in rainbow trout

Scientific Reports ◽

10.1038/s41598-020-62558-y ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 3

Author(s):

Per Hjelmstedt ◽

Henrik Sundh ◽

Jeroen Brijs ◽

Andreas Ekström ◽

Kristina Snuttan Sundell ◽

...

Keyword(s):

Heart Rate ◽

Rainbow Trout ◽

Prophylactic Treatment ◽

Prophylactic Antibiotic ◽

Post Surgery ◽

Recovery Times ◽

Prolonged Recovery ◽

Surgical Recovery ◽

Prophylactic Antibiotic Treatment ◽

Freely Moving

AbstractBio-logging devices can provide unique insights on the life of freely moving animals. However, implanting these devices often requires invasive surgery that causes stress and physiological side-effects. While certain medications in connection to surgeries have therapeutic capacity, others may have aversive effects. Here, we hypothesized that the commonly prescribed prophylactic treatment with enrofloxacin would increase the physiological recovery rate and reduce the presence of systemic inflammation following the intraperitoneal implantation of a heart rate bio-logger in rainbow trout (Oncorhynchus mykiss). To assess post-surgical recovery, heart rate was recorded for 21 days in trout with or without enrofloxacin treatment. Contrary to our hypothesis, treated trout exhibited a prolonged recovery time and elevated resting heart rates during the first week of post-surgical recovery compared to untreated trout. In addition, an upregulated mRNA expression of TNFα in treated trout indicate a possible inflammatory response 21 days post-surgery. Interestingly, the experience level of the surgeon was observed to have a long-lasting impact on heart rate. In conclusion, our study showed no favorable effects of enrofloxacin treatment. Our findings highlight the importance of adequate post-surgical recovery times and surgical training with regards to improving the welfare of experimental animals and reliability of research outcomes.

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Identification of spontaneous cardiac baroreflex episodes at different timescales in rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1998.274.2.h488 ◽

1998 ◽

Vol 274 (2) ◽

pp. H488-H493 ◽

Cited By ~ 2

Author(s):

Marie-Paule Gustin ◽

Catherine Cerutti ◽

Robert Unterreiner ◽

Christian Paultre

Keyword(s):

Heart Rate ◽

Sampling Interval ◽

Statistical Relationship ◽

Sprague Dawley ◽

Time Intervals ◽

Sprague Dawley Rats ◽

Low Pass ◽

Freely Moving ◽

Spontaneous Baroreflex ◽

Long Timescales

To study spontaneous cardiac baroreflex at different timescales, a new method has been developed that identifies such episodes. Mean arterial pressure (MAP) and heart rate (HR) were recorded beat to beat over 1 h in freely moving control ( n = 10) and acutely (1 day before study, n = 7) and chronically (2 wk before study, n = 10) sinoaortic-denervated (SAD) 12- to 14-wk-old male Sprague-Dawley rats. These beat-to-beat time series were successively low-pass filtered seven times and resampled at different time intervals from 0.1 to 6.4 s, allowing different timescales to be scanned. With the use of the Z coefficient, the statistical relationship was estimated for the associations of inverse MAP and HR variations when these inverse MAP and HR variations occurred simultaneously or were time shifted. In control rats and for timescales ≥0.4 s, the highest Zcoefficient(0.38) was obtained when MAP variations preceded inverse HR variations by one sampling interval. The baroreflex origin of this link was demonstrated by its disappearance after acute SAD. In conclusion, this method enabled spontaneous baroreflex episodes to be identified for unusually long timescales without limiting the study to fast, linear, stationary, or oscillating phenomena.

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Quantitative evaluation of ontogenetic change in heart rate and its autonomic regulation in newborn mice with the use of a noninvasive piezoelectric sensor

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01122.2007 ◽

2008 ◽

Vol 294 (4) ◽

pp. H1708-H1715 ◽

Cited By ~ 13

Author(s):

Shinichi Sato

Keyword(s):

Heart Rate ◽

Restraint Stress ◽

Piezoelectric Sensor ◽

Autonomic Control ◽

Adrenergic Stimulation ◽

Newborn Mice ◽

Autonomic Blockade ◽

Freely Moving ◽

First Time ◽

Transient Bradycardia

A reliable basal heart rate (HR) measurement in freely moving newborn mice was accomplished for the first time by using a novel noninvasive piezoelectric transducer (PZT) sensor. The basal HR was ∼320 beats/min at postnatal day (P)0 and increased with age to ∼690 beats/min at P14. Contribution of autonomic control to HR was then assessed. Sympathetic blockade with metoprolol significantly reduced basal HR at both P6 (−236 ± 23 beats/min; mean ± SE) and P12 (−105 ± 8 beats/min), but atropine was without effect, indicating the predominant tonic adrenergic stimulation and absence of vagal control for basal HR in newborn mice. In contrast to stable basal HR during 5-min recording, HR measured by ECG (ECG-HR) was markedly decreased because of the restraint stress of attaching ECG electrodes, with accompanying freezing behavior. ECG-HR lowered and further decreased gradually during 5 min (slow cardiodeceleration) at P0–P3 and rapidly decreased and gradually recovered within 5 min (transient bradycardia) at P9–P14. The response was not uniform in P4–P8 mice: they showed either of these two patterns or sustained bradycardia (9–29%), and the number of mice that showed transient bradycardia increased with age (30–100%) during the period. Studies with autonomic blockade suggest that the slow cardiodeceleration and transient bradycardia are mediated mainly by withdrawal of adrenergic stimulation and phasic vagal activation, respectively, and the autonomic control of HR response to restraint stress is likely to change from the withdrawal of adrenergic stimulation to the phasic vagal activation at different stages during P4–P8 in individual mice. The PZT sensor may offer excellent opportunities to monitor basal HR of small animals noninvasively.

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Independence of heart rate and circadian period in the golden hamster

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1993.264.2.r235 ◽

1993 ◽

Vol 264 (2) ◽

pp. R235-R238

Author(s):

R. Refinetti ◽

M. Menaker

Keyword(s):

Heart Rate ◽

Cardiac Pacemaker ◽

Myocardial Cell ◽

Circadian Oscillation ◽

Circadian Period ◽

Isolated Hearts ◽

Rate Oscillations ◽

The Mean ◽

Freely Moving

Cardiac contractions are under the influence of at least two processes of biological timing, one responsible for the mean level of heart rate (oscillations with a frequency of up to several hundred per minute) and another responsible for the circadian rhythm of heart rate (oscillations with a frequency of one per 24 h). To investigate whether the mean level of heart rate is proportional to the frequency of circadian oscillation, we compared the heart rates of normal golden hamsters (circadian period approximately 24 h) and tau-mutant hamsters (circadian period approximately 20 h). Neither in anesthetized preparations nor in freely moving animals was there a difference in heart rate between the two groups despite the 20% difference in circadian period. Thus the mean level of heart rate seems to be independent of the circadian period. It is likely that the tau gene, which affects the frequency of the circadian pacemaker, has no effect on the intrinsic frequency of the cardiac pacemaker. In vitro studies of isolated hearts or myocardial cell cultures are necessary to confirm this inference.

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