Identification of spontaneous cardiac baroreflex episodes at different timescales in rats

1998 ◽  
Vol 274 (2) ◽  
pp. H488-H493 ◽  
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.

Potential Using of Molecular Characterization and Structure of The Gut Bacterial Community for Postmortem Interval Estimation in Sprague Dawley Rats

2020 ◽  
Author(s):  
Huan Li ◽  
Siruo Zhang ◽  
Ruina Liu ◽  
Lu Yuan ◽  
Di Wu ◽  
...  
Keyword(s):  
Bacterial Community ◽  
High Throughput Sequencing ◽  
Interval Estimation ◽  
The Body ◽  
Time Of Death ◽  
Sprague Dawley ◽  
Upward Trend ◽  
Time Intervals ◽  
Taxa Richness ◽  
Sprague Dawley Rats

Abstract Once the body dies, the inherent microbes of the host begin to break down from the inside and play a key role thereafter. It is hypothesized that after the death certain rectal microbes would change during the decomposition course in the body. This study aimed to investigate the probable shift in the composition of the rectal flora at different time intervals up to 15 days after death and to explore bacterial taxa important for estimating the time of death. At the phylum level, Proteobacteria and Firmicutes showed major shifts, when checked at 11 different intervals, and emerged at most of the postmortem intervals. At the species level, Enterococcus faecalis and Proteus mirabilis existed at most postmortem intervals; the former showed a downward trend after day 5 postmortem, while the latter showed an upward trend. There were obvious differences in bacterial community structure and richness at the phylum, genus, and species levels during the decomposition of the corpse of rats. The phylum, genus, and species taxa richness decreased initially and then increased significantly. The turning point came on day 9 when genus, rather than phylum or species, contained the most information for estimating the time of death. We constructed a prediction model using genus taxon data from high-throughput sequencing, which explained 87.2% of the time since the first sampling within 1 h. Seven bacteria, namely Enterococcus, Proteus, Lactobacillus, unidentified Clostridiales, Vagococcus, unidentified Corynebacteriaceae, and unidentified Enterobacteriaceae, were included in this model. The above-mentioned bacteria showed a promising future for estimating the shortest time of death and results of current study were agreeing with the proposed hypothesis.

A STANDARDIZED METHOD FOR THE PRODUCTION OF HEMORRHAGIC SHOCK IN THE RAT

1955 ◽  
Vol 33 (3) ◽  
pp. 436-447 ◽  
Author(s):  
H. G. Downie ◽  
J. A. F. Stevenson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mortality Rate ◽  
Hemorrhagic Shock ◽  
Respiratory Rate ◽  
Rectal Temperature ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Standardized Method

Although the blood pressure is one of the important criteria in the standardization of hemorrhagic shock in the dog, it has rarely been used for this purpose in the rat. A method resembling the reservoir technique developed by Wiggers and Werle (1942) for the dog using blood pressure as the criterion has been modified for use with the rat. Male Sprague-Dawley rats weighing approximately 400 gm. were used. In the standardization of this technique the blood pressure was reduced to 30 mm. Hg in a 10-min. period of hemorrhage and then maintained at this level by subsequent small hemorrhages into the reservoir until reinfusion indicated the beginning of vascular collapse, at which time all the blood in the reservoir was returned. Considering that those animals which lived longer than 48 hr. were survivors, in a series of 27 animals, 21 died and 6 survived—a mortality rate of 78%.During the hypotensive period there was a consistent and steady drop in the respiratory rate and rectal temperature. The heart rate declined initially and tended to recover as the hypotensive period progressed. After reinfusion the blood pressure rose but. did not reach prehemorrhage levels. Hemorrhage into the bowel and convulsions were significant postreinfusion findings.

Dietary obesity and weight cycling in rats: a model of stress-induced hypertension?

1991 ◽  
Vol 261 (4) ◽  
pp. R848-R857 ◽  
Author(s):  
R. J. Contreras ◽  
S. King ◽  
L. Rives ◽  
A. Williams ◽  
T. Wattleton
Keyword(s):  
Heart Rate ◽  
Sodium Excretion ◽  
Mild Hypertension ◽  
Weight Cycling ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Sweetened Condensed Milk ◽  
Condensed Milk ◽  
Sprague Dawley Rats ◽  
Dietary Obesity

The present study was designed to reproduce the mild hypertension seen in dietary obese weight-cycled rats [P. Ernsberger and D. O. Nelson. Am. J. Physiol. 254 (Regulatory Integrative Comp. Physiol. 23): R47-R55, 1988] and determine whether this mild hypertension was associated with changes in sodium excretion and pressor responsiveness to angiotensin II (ANG II). Male Sprague-Dawley rats were fed pelleted chow (Pellet group) or chow plus sweetened condensed milk (Milk group) or were exposed to four cycles of a 4-day fast alternated with 2 wk of refeeding of pelleted chow and sweetened condensed milk (Cycled group). Blood pressure and heart rate were measured by tail cuff at the onset and last day of each fast and after 3 days of refeeding. During fasting, urine sodium excretion was measured. Mean arterial pressure and heart rate responses to intravenous administration of ANG II (40, 80, and 120 ng/kg), metoprolol (1 mg/kg), and methyl scopolamine (2 mg/kg) were obtained from the femoral artery in awake unrestrained rats. Weight cycling did not lead to mild hypertension or increased bradycardic response to sympathetic blockade with metoprolol. ANG II-elicited pressor responses were similar for Pellet, Milk, and Cycled groups. Sodium excretion did not change with fasting. Mild hypertension developed when obese weight-cycled rats were housed together in groups and not when housed individually. Our preliminary data are consistent with the notion that stress associated with group housing may be a factor in the mild hypertension of obese weight-cycled rats.

Impaired serotonergic regulation of heart rate may underlie reduced baroreflex sensitivity in an animal model of depression

2008 ◽  
Vol 294 (1) ◽  
pp. H474-H480 ◽  
Author(s):  
Cara M. Hildreth ◽  
James R. Padley ◽  
Paul M. Pilowsky ◽  
Ann K. Goodchild
Keyword(s):  
Heart Rate ◽  
Animal Model ◽  
High Frequency ◽  
Neural Control ◽  
Baroreflex Sensitivity ◽  
Cardiac Risk ◽  
Sprague Dawley ◽  
Animal Model Of Depression ◽  
Spontaneous Baroreflex ◽  
Acute Changes

Serotonin (5-HT) is crucial to normal reflex vagal modulation of heart rate (HR). Reduced baroreflex sensitivity [spontaneous baroreflex sensitivity (sBRS)] and HR variability (HRV) reflect impaired neural, particularly vagal, control of HR and are independently associated with depression. In conscious, telemetered Flinders-Sensitive Line (FSL) rats, a well-validated animal model of depression, we tested the hypothesis that cardiovascular regulatory abnormalities are present and associated with deficient serotonergic control of reflex cardiovagal function. In FSL rats and control Flinders-Resistant (FRL) and Sprague-Dawley (SD) rat strains, diurnal measurements of HR, arterial pressure (AP), activity, sBRS, and HRV were made. All strains had normal and similar diurnal variations in HR, AP, and activity. In FRL rats, HR was elevated, contributing to the reduced HRV and sBRS in this strain. In FSL rats, sBRS and high-frequency power HRV were reduced during the night, indicating reduced reflex cardiovagal activity. The ratio of low- to high-frequency bands of HRV was increased in FSL rats, suggesting a relative predominance of cardiac sympathetic and/or reflex activity compared with FRL and SD rats. These data show that conscious FSL rats have cardiovascular regulatory abnormalities similar to depressed humans. Acute changes in HR, AP, temperature, and sBRS in response to 8-hydroxy-2-(di- n-propylamino)tetralin, a 5-HT1A, 5-HT1B, and 5-HT7 receptor agonist, were also determined. In FSL rats, despite inducing an exaggerated hypothermic effect, 8-hydroxy-2-(di- n-propylamino)tetralin did not decrease HR and AP or improve sBRS, suggesting impaired serotonergic neural control of cardiovagal activity. These data suggest that impaired serotonergic control of cardiac reflex function could be one mechanism linking reduced sBRS to increased cardiac risk in depression.

Scintigraphic Evaluation of Decontamination Lotion for Removal of Radioactive Contamination From Skin

2014 ◽  
Vol 8 (2) ◽  
pp. 130-135 ◽  
Author(s):  
Sudha Rana ◽  
Mita Dutta ◽  
Navneet Sharma ◽  
Rajeev Goel ◽  
Abdul Wadood Khan ◽  
...  
Keyword(s):  
Public Health ◽  
Mass Casualty ◽  
Sprague Dawley ◽  
Time Intervals ◽  
Medical Radioisotopes ◽  
Tissue Equivalent ◽  
Sprague Dawley Rats ◽  
Effective Removal ◽  
Tissue Surface ◽  
Skin Contamination

AbstractObjectiveSkin contamination is one of the most likely risks after accidental or occupational radiological accidents. Using scintigraphy, we assessed a topical lotion for its decontamination efficacy (DE) after exposure with short-lived medical radioisotopes technetium Tc 99m (99mTc) and thallium 201Tl (201Tl).MethodsUsing 99mTc (300 ± 5 μCi/100 μl) and 201Tl (100 ± 5 μCi/100 μl), the thoracoabdominal region (shaved skin) of Sprague Dawley rats and human tissue equivalent were contaminated and then decontaminated using cotton swabs soaked in formulated lotion at different time intervals. Static counts were recorded and calculated for DE. Histologic examination was performed on the animal model.ResultsThe DE of the formulation for 99mTc and 201Tl was 85% ± 5 and 88% ± 2, respectively. The prepared formulation effectively removed the radionuclides from the tissue surface.ConclusionsThe formulated lotion assisted in the effective removal of radiocontaminants by decontaminating the radionuclides. Moreover, minimal and easily manageable radioactive waste was generated by this process. Further investigation regarding the infusion of formulated lotion into ready-to-use skin wipes for self-decontamination may be useful for mass casualty scenarios. (Disaster Med Public Health Preparedness. 2014;0:-)

scholarly journals Autonomic control of the heart is altered in Sprague-Dawley rats with spontaneous hydronephrosis

2011 ◽  
Vol 300 (6) ◽  
pp. H2206-H2213 ◽  
Author(s):  
Amy C. Arnold ◽  
Hossam A. Shaltout ◽  
Shea Gilliam-Davis ◽  
Nancy D. Kock ◽  
Debra I. Diz
Keyword(s):  
Heart Rate ◽  
Angiotensin Ii ◽  
Renin Angiotensin System ◽  
Renal Medulla ◽  
Autonomic Control ◽  
Sprague Dawley ◽  
Angiotensin Peptides ◽  
Ras Activation ◽  
Sprague Dawley Rats ◽  
Parasympathetic Function

The renal medulla plays an important role in cardiovascular regulation, through interactions with the autonomic nervous system. Hydronephrosis is characterized by substantial loss of renal medullary tissue. However, whether alterations in autonomic control of the heart are observed in this condition is unknown. Thus we assessed resting hemodynamics and baroreflex sensitivity (BRS) for control of heart rate in urethane/chloralose-anesthetized Sprague-Dawley rats with normal or hydronephrotic kidneys. While resting arterial pressure was similar, heart rate was higher in rats with hydronephrosis (290 ± 12 normal vs. 344 ± 11 mild/moderate vs. 355 ± 13 beats/min severe; P < 0.05). The evoked BRS to increases, but not decreases, in pressure was lower in hydronephrotic rats (1.06 ± 0.06 normal vs. 0.72 ± 0.10 mild/moderate vs. 0.63 ± 0.07 ms/mmHg severe; P < 0.05). Spectral analysis methods confirmed reduced parasympathetic function in hydronephrosis, with no differences in measures of indirect sympathetic activity among conditions. As a secondary aim, we investigated whether autonomic dysfunction in hydronephrosis is associated with activation of the renin-angiotensin system (RAS). There were no differences in circulating angiotensin peptides among conditions, suggesting that the impaired autonomic function in hydronephrosis is independent of peripheral RAS activation. A possible site for angiotensin II-mediated BRS impairment is the solitary tract nucleus (NTS). In normal and mild/moderate hydronephrotic rats, NTS administration of the angiotensin II type 1 receptor antagonist candesartan significantly improved the BRS, suggesting that angiotensin II provides tonic suppression to the baroreflex. In contrast, angiotensin II blockade produced no significant effect in severe hydronephrosis, indicating that at least within the NTS baroreflex suppression in these animals is independent of angiotensin II.

scholarly journals The cardiovascular and endocrine responses to voluntary and forced diving in trained and untrained rats

2010 ◽  
Vol 298 (1) ◽  
pp. R224-R234 ◽  
Author(s):  
Paul F. McCulloch ◽  
Karyn. M. DiNovo ◽  
Tiffanny M. Connolly
Keyword(s):  
Heart Rate ◽  
Sympathetic Activity ◽  
Peripheral Resistance ◽  
Cardiovascular Responses ◽  
Conscious Awareness ◽  
Sprague Dawley ◽  
Diving Response ◽  
Laboratory Rats ◽  
Cardiorespiratory Response ◽  
Sprague Dawley Rats

The mammalian diving response, consisting of apnea, bradycardia, and increased total peripheral resistance, can be modified by conscious awareness, fear, and anticipation. We wondered whether swim and dive training in rats would 1) affect the magnitude of the cardiovascular responses during voluntary and forced diving, and 2) whether this training would reduce or eliminate any stress due to diving. Results indicate Sprague-Dawley rats have a substantial diving response. Immediately upon submersion, heart rate (HR) decreased by 78%, from 453 ± 12 to 101 ± 8 beats per minute (bpm), and mean arterial pressure (MAP) decreased 25%, from 143 ± 1 to 107 ± 5 mmHg. Approximately 4.5 s after submergence, MAP had increased to a maximum 174 ± 3 mmHg. Blood corticosterone levels indicate trained rats find diving no more stressful than being held by a human, while untrained rats find swimming and diving very stressful. Forced diving is stressful to both trained and untrained rats. The magnitude of bradycardia was similar during both voluntary and forced diving, while the increase in MAP was greater during forced diving. The diving response of laboratory rats, therefore, appears to be dissimilar from that of other animals, as most birds and mammals show intensification of diving bradycardia during forced diving compared with voluntary diving. Rats may exhibit an accentuated antagonism between the parasympathetic and sympathetic branches of the autonomic nervous system, such that in the autonomic control of HR, parasympathetic activity overpowers sympathetic activity. Additionally, laboratory rats may lack the ability to modify the degree of parasympathetic outflow to the heart during an intense cardiorespiratory response (i.e., the diving response).

Preservation of coronary reserve by ivabradine-induced reduction in heart rate in infarcted rats is associated with decrease in perivascular collagen

2007 ◽  
Vol 293 (1) ◽  
pp. H590-H598 ◽  
Author(s):  
Eduard I. Dedkov ◽  
Wei Zheng ◽  
Lance P. Christensen ◽  
Robert M. Weiss ◽  
Florence Mahlberg-Gaudin ◽  
...  
Keyword(s):  
Heart Rate ◽  
Myocardial Perfusion ◽  
Transforming Growth Factor ◽  
Diastolic Pressure ◽  
Left Ventricular ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Coronary Reserve ◽  
Osmotic Pumps ◽  
Sprague Dawley Rats

We tested the hypothesis that chronically reducing the heart rate in infarcted middle-aged rats using ivabradine (IVA) would induce arteriolar growth and attenuate perivascular collagen and, thereby, improve maximal perfusion and coronary reserve in the surviving myocardium. Myocardial infarction (MI) was induced in 12-mo-old male Sprague-Dawley rats, which were then treated with either IVA (10.5 mg·kg−1·day−1; MI + IVA) or placebo (MI) via intraperitoneal osmotic pumps for 4 wk. Four weeks of IVA treatment limited the increase in left ventricular end-diastolic pressure and the decrease in ejection fraction but did not affect the size of the infarct, the magnitude of myocyte hypertrophy, or the degree of arteriolar and capillary growth. However, treatment reduced interstitial and periarteriolar collagen in the surviving myocardium of MI + IVA rats. The reduced periarteriolar collagen content was associated with improvement in maximal myocardial perfusion and coronary reserve. Although the rates of proliferation of periarteriolar fibroblasts were similar in the MI and MI + IVA groups, the expression levels of the AT1 receptor and transforming growth factor (TGF)-β1 in the myocardium, as well as the plasma level of the ANG II peptide, were lower in treated rats 14 days after MI. Therefore, our data reveal that improved maximal myocardial perfusion and coronary reserve in MI + IVA rats are most likely the result of reduced periarteriolar collagen rather than enhanced arteriolar growth.

scholarly journals Cooling-Evoked Hemodynamic Perturbations Facilitate Sympathetic Activity with Subsequent Myogenic Vascular Oscillations via Alpha2-Adrenergic Receptors

2017 ◽  
pp. 449-457 ◽  
Author(s):  
Y.-H. LIN ◽  
Y.-P. LIU ◽  
Y.-C. LIN ◽  
P.-L. LEE ◽  
C.-S. TUNG
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressor Response ◽  
Low Frequency ◽  
Power Spectral Analysis ◽  
Sprague Dawley ◽  
Cold Stimulation ◽  
Very Low Frequency ◽  
Power Spectral ◽  
Sprague Dawley Rats

This study extends our previous work by examining the effects of alpha2-adrenoceptors under cold stimulation involving the increase of myogenic vascular oscillations as increases of very-low-frequency and low-frequency of the blood pressure variability. Forty-eight adult male Sprague-Dawley rats were randomly divided into four groups: vehicle; yohimbine; hexamethonium+yohimbine; guanethidine+yohimbine. Systolic blood pressure, heart rate, power spectral analysis of spontaneous blood pressure and heart rate variability and spectral coherence at very-low-frequency (0.02 to 0.2 Hz), low-frequency (0.2 to 0.6 Hz), and high-frequency (0.6 to 3.0 Hz) regions were monitored using telemetry. Key findings are as follows: 1) Cooling-induced pressor response was attenuated by yohimbine and further attenuated by hexamethonium+yohimbine and guanethidine+yohimbine, 2) Cooling-induced tachycardia response of yohimbine was attenuated by hexame-thonium+yohimbine and guanethidine+yohimbine, 3) Different patterns of power spectrum reaction and coherence value compared hexamethonium+yohimbine and guanethi-dine+yohimbine to yohimbine alone under cold stimulation. The results suggest that sympathetic activation of the postsynaptic alpha2-adrenoceptors causes vasoconstriction and heightening myogenic vascular oscillations, in turn, may increase blood flow to prevent tissue damage under stressful cooling challenge.

Effect of circulating vasopressin on arterial pressure regulation in rats

1989 ◽  
Vol 257 (1) ◽  
pp. H209-H218 ◽  
Author(s):  
C. M. Pawloski ◽  
N. M. Eicker ◽  
L. M. Ball ◽  
M. L. Mangiapane ◽  
G. D. Fink
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Body Fluid ◽  
Area Postrema ◽  
Sodium Intake ◽  
Blood Levels ◽  
Fluid Composition ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Autonomic Cardiovascular Control

It has been hypothesized that moderately increased blood levels of arginine vasopressin (AVP) contribute to the development and/or maintenance of hypertension. In this study, male Sprague-Dawley rats on a fixed 1 meq daily sodium intake received 10-day intravenous infusions of 0.2 and 2.0 ng.kg-1.min-1 AVP. The higher infusion rate was above the acute vasoconstrictor threshold for AVP administration and also produced a maximal antidiuretic effect. During chronic AVP administration, however, daily mean arterial pressure, heart rate, and body fluid composition were not changed, despite a maintained antidiuresis. To test the hypothesis that circulating AVP failed to cause hypertension as a result of sensitization of the baroreflex or a direct sympathoinhibitory effect of the peptide, additional experiments were performed in rats subjected to sinoaortic denervation (SAD) or ablation of the area postrema (APX). Infusion of AVP for 10 days into SAD or APX rats caused a sustained antidiuresis but did not change arterial pressure, heart rate, or body fluid composition. In all groups of rats, the depressor response to ganglionic blockade (20 mg/kg hexamethonium) was used to estimate the autonomic component of resting arterial pressure; no change in autonomic cardiovascular control was found using this method in any of the groups during AVP infusion. Long-term elevation of plasma AVP in rats, therefore, does not cause hypertension or significantly affect autonomic regulation of arterial pressure.

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