Alterations in the cardiovascular control by the chemoreflex and the baroreflex in old rats

1996 ◽  
Vol 270 (1) ◽  
pp. R310-R313 ◽  
Author(s):  
K. G. Franchini ◽  
E. D. Moreira ◽  
F. Ida ◽  
E. M. Krieger
Keyword(s):  
Heart Rate ◽  
Aging Process ◽  
Cardiovascular Function ◽  
Cardiovascular Control ◽  
Autonomic Control ◽  
Young Rats ◽  
Reflex Bradycardia ◽  
Pressor Responses ◽  
Old Rats

The aging process is associated with alterations in the autonomic control of cardiovascular function. In the present study, we observed that reflex bradycardia and tachycardia produced by pressor and depressor agents were attenuated in old (24 mo) rats [70 and 56% of responses in young rats (4 mo), respectively]. In contrast, the bradycardia induced by chemoreflex activation with increasing doses of KCN (60, 100, 140, and 180 micrograms/kg) was greater in old [-30 +/- 19, -155 +/- 32, -198 +/- 15, and -204 +/- 24 beats/ min (bpm)] than in young rats [-13 +/- 6, -75 +/- 20 (P < 0.05), -99 +/- 26 (P < 0.05), and -103 +/- 20 (P < 0.05) bpm]. The chemoreflex-pressor responses tended to be greater in old (12 +/- 6, 47 +/- 6, 54 +/- 7, and 55 +/- 5 mmHg) than in young rats (4 +/- 2, 32 +/- 8, 42 +/- 6, and 44 +/- 4 mmHg), but the differences between both groups were not statistically significant. However, pressor responses were higher in old rats after the chemoreflex-activated bradycardia was attenuated by atropine (4 mg/kg iv) [old (17 +/- 9(1) P < 0.05; 57 +/- 4, P < 0.05; 61 +/- 4; and 64 +/- 5 mmHg) vs. young (3 +/- 2, 29 +/- 9(1) 50 +/- 5, and 58 +/- 7 mmHg)]. Administration of the alpha 1-blocker prazosin (1 mg/kg iv) blunted pressor responses but did not change the bradycardia induced by chemoreflex in both groups. In conclusion, our data indicate that the bradycardia and pressor responses to chemoreflex activation were exaggerated, whereas the heart rate responses (bradycardia and tachycardia) to baroreflex were depressed in old rats.

Aging and baroreflex control of RSNA and heart rate in rats

2000 ◽  
Vol 279 (5) ◽  
pp. R1865-R1871 ◽  
Author(s):  
M. C. Irigoyen ◽  
E. D. Moreira ◽  
A. Werner ◽  
F. Ida ◽  
M. D. Pires ◽  
...  
Keyword(s):  
Heart Rate ◽  
Sympathetic Nerve Activity ◽  
Autonomic Control ◽  
Baroreflex Control ◽  
Renal Sympathetic Nerve Activity ◽  
Sympathetic Function ◽  
Arterial Blood ◽  
Reflex Bradycardia ◽  
Old Rats ◽  
Renal Sympathetic

Aging is associated with altered autonomic control of cardiovascular function, but baroreflex function in animal models of aging remains controversial. In this study, pressor and depressor agent-induced reflex bradycardia and tachycardia were attenuated in conscious old (24 mo) rats [57 and 59% of responses in young (10 wk) Wistar rats, respectively]. The intrinsic heart rate (HR, 339 ± 5 vs. 410 ± 10 beats/min) was reduced in aged animals, but no intergroup differences in resting mean arterial blood pressure (MAP, 112 ± 3 vs. 113 ± 5 mmHg) or HR (344 ± 9 vs. 347 ± 9 beats/min) existed between old and young rats, respectively. The aged group also exhibited a depressed (49%) parasympathetic contribution to the resting HR value (vagal effect) but preserved sympathetic function after intravenous methylatropine and propranolol. An implantable electrode revealed tonic renal sympathetic nerve activity (RSNA) was similar between groups. However, old rats showed impaired baroreflex control of HR and RSNA after intravenous nitroprusside (−0.63 ± 0.18 vs. −1.84 ± 0.4 bars · cycle−1 · mmHg−1 · s−1). Therefore, aging in rats is associated with 1) preserved baseline MAP, HR, and RSNA, 2) impaired baroreflex control of HR and RSNA, and 3) altered autonomic control of resting HR.

Abated cardiovascular responses to chronic oral lisinopril treatment in conscious elderly rats

1999 ◽  
Vol 276 (5) ◽  
pp. R1408-R1415 ◽  
Author(s):  
Ruben Buñag ◽  
Jennifer Mellick ◽  
Brandy Allen
Keyword(s):  
Baroreflex Sensitivity ◽  
Cardiovascular Effects ◽  
Cardiovascular Responses ◽  
Male Rats ◽  
Adrenergic Blockade ◽  
Reflex Bradycardia ◽  
Age Related ◽  
Pressor Responses ◽  
Mean Pressure ◽  
Old Rats

To determine whether the cardiovascular effects of chronic treatment with lisinopril are age related, we compared baroreflex sensitivity and pressor responsiveness in 4-mo- and 21-mo-old male rats that had been given oral lisinopril daily for 4 wk. Reflex bradycardia elicited by elevating blood pressure with phenylephrine was stronger in 4-mo-old rats than it was in 21-mo-old rats and also stronger in lisinopril-treated rats than it was in untreated rats of the same age. Pressor responses to angiotensin or norepinephrine were recorded after combined cholinergic and β-adrenergic blockade and then analyzed not only as absolute but also as percent increases in mean pressure. Although pressor responses seemed to be slightly reduced by lisinopril when expressed as absolute increases in mean pressure, corresponding percent increases were always larger in 4-mo-old rats than they were in 21-mo-old rats and were clearly enhanced by lisinopril more in younger rats. The stronger overall enhancement of pressor responsiveness and reflex bradycardia in younger rats suggests that the cardiovascular effects of lisinopril diminish with advancing age.

scholarly journals Age and autonomic control, but not cerebral oxygenation, are significant determinants of EEG spectral power in children

SLEEP ◽  
2019 ◽  
Vol 42 (9) ◽  
Author(s):  
Lisa M Walter ◽  
Knarik Tamanyan ◽  
Aidan J Weichard ◽  
Sarah N Biggs ◽  
Margot J Davey ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cerebral Oxygenation ◽  
Spectral Power ◽  
Sleep Stage ◽  
Low Frequency ◽  
Power Spectral Analysis ◽  
Cardiovascular Control ◽  
Autonomic Control ◽  
Eeg Spectral Power ◽  
Low Frequency Power

AbstractStudy ObjectivesSleep disordered breathing (SDB) in children has significant effects on daytime functioning and cardiovascular control; attributed to sleep fragmentation and repetitive hypoxia. Associations between electroencephalograph (EEG) spectral power, autonomic cardiovascular control and cerebral oxygenation have been identified in adults with SDB. To date, there have been no studies in children. We aimed to assess associations between EEG spectral power and heart rate variability as a measure of autonomic control, with cerebral oxygenation in children with SDB.MethodsOne hundred sixteen children (3–12 years) with SDB and 42 controls underwent overnight polysomnography including measurement of cerebral oxygenation. Power spectral analysis of the EEG derived from C4-M1 and F4-M1, quantified delta, theta, alpha, and beta waveforms during sleep. Multiple regression tested whether age, SDB severity, heart rate (HR), HR variability (HRV), and cerebral oxygenation were determinants of EEG spectral power.ResultsThere were no differences in EEG spectral power derived from either central or frontal regions for any frequency between children with different severities of SDB so these were combined. Age, HR, and HRV low frequency power were significant determinants of EEG spectral power depending on brain region and sleep stage.ConclusionThe significant findings of this study were that age and autonomic control, rather than cerebral oxygenation and SDB severity, were predictive of EEG spectral power in children. Further research is needed to elucidate how the physiology that underlies the relationship between autonomic control and EEG impacts on the cardiovascular sequelae in children with SDB.

Effect of Naloxone on the Defective Autonomic Control of Heart Rate in Uraemic Patients

1985 ◽  
Vol 69 (1) ◽  
pp. 81-86 ◽  
Author(s):  
C. Zoccali ◽  
M. Ciccarelli ◽  
F. Mallamaci ◽  
Q. Maggiore
Keyword(s):  
Heart Rate ◽  
Normal Subjects ◽  
Autonomic Control ◽  
Endogenous Opioids ◽  
Valsalva Manoeuvre ◽  
Diabetic Patients ◽  
Opiate Antagonist ◽  
Reflex Bradycardia ◽  
Standing Blood Pressure

1. The role of endogenous opioids on the reflex cardiovascular control of chronic uraemic patients was investigated. 2. The opiate antagonist naloxone administered intravenously caused a significant increase in the abnormal Valsalva manoeuvre ratio in nine chronic uraemic patients, but it had no effect in six diabetic patients with normal renal function, whose response to the Valsalva manoeuvre was similar to that of chronic uraemic patients. Naloxone had no effect in eight normal subjects. 3. The increase in the Valsalva ratio observed in uraemic patients was due to restoration of the parasympathetically mediated reflex bradycardia of the release phase of the manoeuvre. 4. Naloxone did not modify supine and standing blood pressure and heart rate in any group. 5. Endogenous opioids may be involved in the defective autonomic control of heart rate in uraemic patients.

Effects of the Selective H1and H2Histamine Receptor Antagonists Loratadine and Ranitidine on Autonomic Control of the Heart

2002 ◽  
Vol 96 (2) ◽  
pp. 336-341 ◽  
Author(s):  
Michael A. Nault ◽  
Brian Milne ◽  
Joel L. Parlow
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Baroreflex Sensitivity ◽  
Cardiovascular Control ◽  
Autonomic Control ◽  
Total Power ◽  
Receptor Antagonists ◽  
H2 Receptor Antagonists ◽  
H2 Receptor

Background H1 and H2 histamine receptor subtypes are present throughout the heart and may be involved in disturbances of cardiac rhythm that occur during anaphylaxis. Although H1 and H2 receptor antagonists are used in the treatment of anaphylaxis, there have been reports implicating these drugs in the genesis of dysrhythmias. This study was designed to investigate the effects of the selective H1 and H2 receptor antagonists loratadine and ranitidine on physiologic autonomic control of the healthy cardiovascular system. Methods Using a double-blind, crossover design, 14 healthy volunteers completed the protocol and were randomized to receive one dose of loratadine (20 mg), ranitidine (300 mg), or placebo on each of three separate testing sessions. Continuous electrocardiogram and BP recordings were obtained before and 3 h after administration of study drug. Effects on cardiac autonomic control were quantified using power spectral analysis of heart rate variability and calculation of spontaneous baroreflex sensitivity. Results Neither placebo nor loratadine significantly altered indices of autonomic cardiovascular control. Conversely, H2 antagonism with ranitidine resulted in a 23.3% decrease in baroreflex sensitivity (P &lt; 0.05) and a corresponding 25.0% decrease in the ratio of high frequency to total power of heart rate variability, both indices of parasympathetic modulation (P &lt; 0.01). Furthermore, ranitidine evoked a concomitant 103.8% increase in the ratio of low to high frequency power of heart rate variability, an index of sympathetic control (P &lt; 0.01). Conclusions H1 receptor antagonism with loratadine does not influence physiologic cardiovascular control in young healthy subjects. However, the altered cardiac sympathovagal balance after oral administration of the H2 receptor antagonist ranitidine indicates a shift toward sympathetic predominance in heart rate control. The authors postulate that this could have implications regarding susceptibility to arrhythmias in conditions of heightened sympathetic stimulation.

Correlation in the heart rate data

1998 ◽  
Vol 2 ◽  
pp. 141-148
Author(s):  
J. Ulbikas ◽  
A. Čenys ◽  
D. Žemaitytė ◽  
G. Varoneckas
Keyword(s):  
Nonlinear Dynamics ◽  
Experimental Data ◽  
Heart Rate ◽  
Time Series ◽  
Cardiovascular Function ◽  
Statistical Properties ◽  
Rate Data ◽  
Heart Rate Data ◽  
Dynamical Nature ◽  
Analysis Of Time Series

Variety of methods of nonlinear dynamics have been used for possibility of an analysis of time series in experimental physiology. Dynamical nature of experimental data was checked using specific methods. Statistical properties of the heart rate have been investigated. Correlation between of cardiovascular function and statistical properties of both, heart rate and stroke volume, have been analyzed. Possibility to use a data from correlations in heart rate for monitoring of cardiovascular function was discussed.

scholarly journals Caffeine affects autonomic control of heart rate and blood pressure recovery after aerobic exercise in young adults: a crossover study

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Luana Almeida Gonzaga ◽  
Luiz Carlos Marques Vanderlei ◽  
Rayana Loch Gomes ◽  
Vitor Engrácia Valenti
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Young Adults ◽  
Aerobic Exercise ◽  
Crossover Study ◽  
Autonomic Control ◽  
Pressure Recovery

AUTONOMIC CONTROL OF HEART RATE AFTER EXERCISE IN TRAINED WRESTLERS

2013 ◽  
Vol 30 (2) ◽  
pp. 111-115 ◽  
Author(s):  
Carlos Henríquez ◽  
Eduardo Báez ◽  
Astrid Von Oetinger ◽  
Rodrigo Cañas ◽  
Rodrigo Ramírez
Keyword(s):  
Heart Rate ◽  
Autonomic Control

scholarly journals Cortisol Levels and Autonomic Control of Heart Rate in Healthy Subjects

2017 ◽  
Vol 17 (2) ◽  
pp. 5-14 ◽  
Author(s):  
Milana Drumond Ramos Santana ◽  
Eli Carlos Martiniano ◽  
Larissa Raylane Lucas Monteiro ◽  
Maria Do Socorro Santos De Oliveira ◽  
Vitor E. Valenti ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Salivary Cortisol ◽  
Healthy Subjects ◽  
Autonomic Control ◽  
Autonomic Modulation ◽  
Cardiac Autonomic Modulation ◽  
Cortisol Levels ◽  
Modulation Methods

AbstractIntroduction: There is an increase in level of stress in the general population because of the social, personal and professional demands. Currently, there are only simple tools that can safely measure this stress such as levels of cortisol and heart rate variability (HRV). Objective: To analyze the relationship between salivary cortisol and the cardiac autonomic modulation. Methods: A total of fifty-one male and female subjects between 18 and 40 years old were evaluated. Saliva collection was achieved for the salivary cortisol dosage. The collection was performed through the SalivetteR tube. After this collection, the median cortisol levels (0.24 ug/dl) were analyzed and the volunteers were divided into two groups: i) cortisol below the mediane ii) cortisol above the median. After this division, each group consisted of 25 volunteers and then was verified the following information: age, gender, weight, height, body mass index (BMI), blood pressure. Shortly thereafter was assessment of cardiac autonomic modulation por meio da HRV. The Polar RS800cx heart rate receiver was placed on the chest of the volunteers, in the vicinity of the distal third of the sternum. The volunteers were instructed to remain in rest with spontaneous breathing in dorsal position for 20 minutes. HRV analysis included geometric, time and frequency domain indices. Results: There were no statistical differences for the two groups regarding systolic and diastolic blood pressure, heart rate, RR intervals or linear and frequency indices for the volunteers. In addition, also there was no correlation the cortisol with the analyzed variables (SAP, p=0.460; DAP, p = 0.270; HR, p = 0.360; RR, p = 0.380; SDNN, p = 0.510; rMSSD, p = 0.660; pNN50, p = 0.820; RRtri, p = 0.170; TINN, p = 0.470; SD1, p = 0.650; SD2, p = 0.500; LF [ms2], p = 0.880; LF [nu], p = 0.970; HF [ms2], p = 0.870; HF [nu], p = 0.960; LF/HF, p = 0.380 Conclusion: Heart rate variability autonomic control was unchanged in healthy subjects with physiological distribution of salivary cortisol levels. There was no association between normal salivary cortisol and resting autonomic regulation of heart rate.

Effects of temperature and wind on facial temperature, heart rate, and sensation

1976 ◽  
Vol 40 (2) ◽  
pp. 127-131 ◽  
Author(s):  
J. LeBlanc ◽  
B. Blais ◽  
B. Barabe ◽  
J. Cote
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Subjective Evaluation ◽  
Temperature Measurements ◽  
Wind Speeds ◽  
Reflex Bradycardia ◽  
The Face ◽  
Cooling Effects ◽  
Effects Of Temperature ◽  
Cold Wind

Skin temperature measurements of the face have shown that the cheek cools faster than the nose and the nose faster than the forehead. The cooling effect of wind is maximum at wind speeds between 4.5 and 6.7 m/s. Cold winds produce significant bradycardia, which is, however, much more pronounced during the expiratory phase of respiration. A significant correlation was noted between cooling of face and the reflex bradycardia observed. Similarly, a very significant correlation was noted between drop in skin temperature and subjective evaluation of cold discomfort. Consequently, the drop in skin temperature, reflex bradycardia, and subjective evaluation are parameters which are directly affected by cold wind and can be used as adequate indicators of the degree of discomfort. When comparing the present results with the windchill index, it was found that in the zone described as “dangerously cold” the index fits well with the physiological measurements. In the zone described as “bitterly cold,” the index by comparison with actual skin temperature measurements and subjective evaluation underestimates the cooling effects of combined temperature and wind by approximately 10 degrees C.

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