Assessing baroreflex gain from spontaneous variability in conscious dogs: role of causality and respiration

2000 ◽  
Vol 279 (5) ◽  
pp. H2558-H2567 ◽  
Author(s):  
A. Porta ◽  
G. Baselli ◽  
O. Rimoldi ◽  
A. Malliani ◽  
M. Pagani
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Parametric Models ◽  
Conscious Dogs ◽  
Regulatory Mechanisms ◽  
Stimulation Of

A double exogenous autoregressive (XXAR) causal parametric model was used to estimate the baroreflex gain (αXXAR) from spontaneous R-R interval and systolic arterial pressure (SAP) variabilities in conscious dogs. This model takes into account 1) effects of current and past SAP variations on the R-R interval (i.e., baroreflex-mediated influences), 2) specific perturbations affecting R-R interval independently of baroreflex circuit (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at frequencies slower than respiration), and 3) influences of respiration-related sources acting independently of baroreflex pathway (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at respiratory rate, including the effect of stimulation of low-pressure receptors). Under control conditions, αXXAR = 14.7 ± 7.2 ms/mmHg. It decreases after nitroglycerine infusion and coronary artery occlusion, even though the decrease is significant only after nitroglycerine, and it is completely abolished by total arterial baroreceptor denervation. Moreover, αXXAR is comparable to or significantly smaller than (depending on the experimental condition) the baroreflex gains derived from sequence, power spectrum [at low frequency (LF) and high frequency (HF)], and cross-spectrum (at LF and HF) analyses and from less complex causal parametric models, thus demonstrating that simpler estimates may be biased by the contemporaneous presence of regulatory mechanisms other than baroreflex mechanisms.

Analysis of short-term oscillations of R-R and arterial pressure in conscious dogs

1990 ◽  
Vol 258 (4) ◽  
pp. H967-H976 ◽  
Author(s):  
O. Rimoldi ◽  
S. Pierini ◽  
A. Ferrari ◽  
S. Cerutti ◽  
M. Pagani ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
High Frequency ◽  
Low Frequency ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Conscious Dogs ◽  
Total Power ◽  
Vagal Activity ◽  
Short Term ◽  
Third Order

We studied the neural determinants of the second (i.e., high frequency, HF)- and third-order (i.e., low frequency, LF) spontaneous oscillations of heart period (R-R interval) and arterial pressure (AP) in conscious dogs, with the hypothesis that they might furnish quantitative markers of autonomic controlling activities. Spectral analysis of simultaneous R-R and AP variabilities quantified these oscillations that were also evaluated in units normalized by total power to focus on the balance of these two major components. At rest we observed a prevalent HF component (approximately 0.25 Hz) in R-R and AP variabilities that was synchronous with respiration. This HF component of R-R variability disappeared after atropine infusion and can be considered a marker mostly of vagal activity. When baroreceptor unloading, obtained by moderate hypotension, increased sympathetic activity the LF component increased in R-R, systolic, and diastolic AP variabilities. This increase in LF was not present after ganglionic blockade or after chronic arterial baroreceptor denervation. After chronic bilateral stellectomy, hypotension was not accompanied by an increase in LF component of R-R variability, while LF component remained in AP variability. An increase in LF component of R-R and AP variabilities was observed during transient coronary artery occlusion.

The role of central vasopressin receptors in the modulation of autonomic cardiovascular controls: a spectral analysis study

2006 ◽  
Vol 291 (6) ◽  
pp. R1579-R1591 ◽  
Author(s):  
Sanja Milutinović ◽  
David Murphy ◽  
Nina Japundžić-Žigon
Keyword(s):  
Blood Pressure ◽  
Spectral Analysis ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Short Term ◽  
Vasopressin Receptors ◽  
The Central Nervous System ◽  
Respiratory Stimulation ◽  
Stimulation Of

Although it has been suggested that vasopressin (VP) acts within the central nervous system to modulate autonomic cardiovascular controls, the mechanisms involved are not understood. Using nonpeptide, selective V1a, V1b, and V2 antagonists, in conscious rats, we assessed the roles of central VP receptors, under basal conditions, after the central application of exogenous VP, and after immobilization, on cardiovascular short-term variability. Equidistant sampling of blood pressure (BP) and heart rate (HR) at 20 Hz allowed direct spectral analysis in very-low frequency (VLF-BP), low-frequency (LF-BP), and high-frequency (HF-BP) blood pressure domains. The effect of VP antagonists and of exogenous VP on body temperature (Tb) was also investigated. Under basal conditions, V1a antagonist increased HF-BP and Tb, and this was prevented by metamizol. V1b antagonist enhanced HF-BP without affecting Tb, and V2 antagonist increased VLF-BP variability which could be prevented by quinapril. Immobilization increased BP, LF-BP, HF-BP, and HF-HR variability. V1a antagonist prevented BP and HR variability changes induced by immobilization and potentiated tachycardia. V1b antagonist prevented BP but not HR variability changes, whereas V2 antagonist had no effect. Exogenous VP increased systolic arterial pressure (SAP) and HF-SAP variability, and this was prevented by V1a and V1b but not V2 antagonist pretreatment. Our results suggest that, under basal conditions, VP, by stimulation of V1a, V1b, and cognate V2 receptors, buffers BP variability, mostly due to thermoregulation. Immobilization and exogenous VP, by stimulation of V1a or V1b, but not V2 receptors, increases BP variability, revealing cardiorespiratory adjustment to stress and respiratory stimulation, respectively.

Tachypnea after stimulation of afferent cardiac sympathetic nerve fibers

1976 ◽  
Vol 230 (4) ◽  
pp. 1003-1007 ◽  
Author(s):  
Y Uchida
Keyword(s):  
Sympathetic Nerve ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Nerve Fibers ◽  
Left Ventricular ◽  
Regulation Of Respiration ◽  
Cardiac Sympathetic Nerve ◽  
Sympathetic Nerve Fibers ◽  
Stimulation Of

The role of afferent cardiac sympathetic nerve fibers in the regulation of respiration has been examined. Application of potassium chloride or lactic acid solutions to the left ventricular surface of anesthetized vagotomized dogs resulted in a decrease in the manimum firing rate and shortening in period duration of firing of phrenic nerves. Also, application of the agents caused a decrease in amplitude and an increase in rate of respiratory thoracic movements. The same changes in phrenic nerve activity and respiratory movements were produced by coronary artery occlusion and centrifugal electrical stimulation of the left inferior cardiac nerves. The results indicate tachypnea that can be produced by excitation of afferent cardiac sympathetic nerve fibers.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

scholarly journals Deep Brain Stimulation of the Posterior Insula in Chronic Pain: A Theoretical Framework

2021 ◽  
Vol 11 (5) ◽  
pp. 639
Author(s):  
David Bergeron ◽  
Sami Obaid ◽  
Marie-Pierre Fournier-Gosselin ◽  
Alain Bouthillier ◽  
Dang Khoa Nguyen
Keyword(s):  
Chronic Pain ◽  
Electrical Stimulation ◽  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
High Frequency ◽  
Brain Lesion ◽  
Low Frequency ◽  
Posterior Insula ◽  
Deep Brain ◽  
Stimulation Of

Introduction: To date, clinical trials of deep brain stimulation (DBS) for refractory chronic pain have yielded unsatisfying results. Recent evidence suggests that the posterior insula may represent a promising DBS target for this indication. Methods: We present a narrative review highlighting the theoretical basis of posterior insula DBS in patients with chronic pain. Results: Neuroanatomical studies identified the posterior insula as an important cortical relay center for pain and interoception. Intracranial neuronal recordings showed that the earliest response to painful laser stimulation occurs in the posterior insula. The posterior insula is one of the only regions in the brain whose low-frequency electrical stimulation can elicit painful sensations. Most chronic pain syndromes, such as fibromyalgia, had abnormal functional connectivity of the posterior insula on functional imaging. Finally, preliminary results indicated that high-frequency electrical stimulation of the posterior insula can acutely increase pain thresholds. Conclusion: In light of the converging evidence from neuroanatomical, brain lesion, neuroimaging, and intracranial recording and stimulation as well as non-invasive stimulation studies, it appears that the insula is a critical hub for central integration and processing of painful stimuli, whose high-frequency electrical stimulation has the potential to relieve patients from the sensory and affective burden of chronic pain.

scholarly journals The Influence ofNrf2on Cardiac Responses to Environmental Stressors

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Reuben Howden ◽  
Eva Gougian ◽  
Marcus Lawrence ◽  
Samantha Cividanes ◽  
Wesley Gladwell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Therapeutic Strategies ◽  
Environmental Stressors ◽  
Total Power ◽  
Airborne Pollutants ◽  
Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

Reduction of infarct size with d-myo-inositol trisphosphate: role of PI3-kinase and mitochondrial KATP channels

2006 ◽  
Vol 290 (2) ◽  
pp. H830-H836 ◽  
Author(s):  
Karin Przyklenk ◽  
Michelle Maynard ◽  
Peter Whittaker
Keyword(s):  
Infarct Size ◽  
Katp Channels ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Additional Treatment ◽  
Pi3 Kinase ◽  
Mitochondrial Katp Channels ◽  
Tetrazolium Staining ◽  
Sparing Effect

Prophylactic treatment with d- myo-inositol 1,4,5-trisphosphate hexasodium [d- myo-Ins(1,4,5)P3], the sodium salt of the endogenous second messenger Ins(1,4,5)P3, triggers a reduction of infarct size comparable in magnitude to that seen with ischemic preconditioning (PC). However, the mechanisms underlying d- myo-Ins(1,4,5)P3-induced protection are unknown. Accordingly, our aim was to investigate the role of four archetypal mediators implicated in PC and other cardioprotective strategies (i.e., PKC, PI3-kinase/Akt, and mitochondrial and/or sarcolemmal KATP channels) in the infarct-sparing effect of d- myo-Ins(1,4,5)P3. Fifteen groups of isolated buffer-perfused rabbit hearts [5 treated with d- myo-Ins(1,4,5)P3, 5 treated with PC, and 5 control cohorts] underwent 30 min of coronary artery occlusion and 2 h of reflow. One set of control, d- myo-Ins(1,4,5)P3, and PC groups received no additional treatment, whereas the remaining sets were infused with chelerythrine, LY-294002, 5-hydroxydecanoate (5-HD), or HMR-1098 [inhibitors of PKC, PI3-kinase, and mitochondrial and sarcolemmal ATP-sensitive K+ (KATP) channels, respectively]. Infarct size (delineated by tetrazolium staining) was, as expected, significantly reduced in both d- myo-Ins(1,4,5)P3- and PC-treated hearts versus controls. d- myo-Ins(1,4,5)P3-induced cardioprotection was blocked by 5-HD but not HMR-1098, thereby implicating the involvement of mitochondrial, but not sarcolemmal, KATP channels. Moreover, the benefits of d- myo-Ins(1,4,5)P3 were abrogated by LY-294002, whereas, in contrast, chelerythrine had no effect. These latter pharmacological data were corroborated by immunoblotting: d- myo-Ins(1,4,5)P3 evoked a significant increase in expression of phospho-Akt but had no effect on the activation/translocation of the cardioprotective ε-isoform of PKC. Thus PI3-kinase/Akt signaling and mitochondrial KATP channels participate in the reduction of infarct size afforded by prophylactic administration of d- myo-Ins(1,4,5)P3.

Higher order neurons in buccal ganglia of Pleurobranchaea elicit vomiting motor activity

1983 ◽  
Vol 50 (3) ◽  
pp. 658-670 ◽  
Author(s):  
A. D. McClellan
Keyword(s):  
High Frequency ◽  
Motor Pattern ◽  
Higher Order ◽  
Root Activity ◽  
Command Neurons ◽  
Sensory Inputs ◽  
Buccal Ganglia ◽  
Output Pattern ◽  
Stimulation Of

The buccal mass of the gastropod Pleurobranchaea is used during a regurgitation response that consists of a writhing phase interrupted by brief periodic bouts of a vomiting phase (17, 20). During transitions from writhing to vomiting, specific changes occur in the motor pattern (19, 20). Evidence is presented suggesting that at least some of the initiation or "command" neurons for vomiting reside in the buccal ganglia. The present paper examines the role of two candidate vomiting-initiation cells, the ventral white cells (VWC) and midganglionic cells (MC), in the buccal ganglia of isolated nervous systems. Stimulation of single VWCs activates a vomiting motor pattern, consisting in part of alternating buccal root activity. Furthermore, the VWCs fire in high-frequency bursts during episodes (i.e., bouts) of this same vomiting pattern. Mutual reexcitation between the VWCs and motor pattern generator (MPG) appears to produce the accelerated buildup and maintenance of vomiting rhythms. Brief stimulation of single MCs "triggers" bouts of a vomiting motor pattern, but the membrane potential of this cell is only modulated during this same pattern, at least in the isolated nervous system. It is proposed that in intact animals the MCs are activated by sensory inputs and briefly excite the VWC-MPG network, thereby turning on the mutual reexcitatory mechanism mentioned above and switching the output pattern. A general implication for gastropod research is that higher order neurons that activate buccal root activity cannot automatically be given the function of "feeding command neuron," as some cells clearly control other responses, such as vomiting.

scholarly journals Peranan Lingkungan Sosial terhadap Pembentukan Karakter Peduli Lingkungan Mahasiswa Pendidikan Geografi di Universitas Samudra Langsa

2018 ◽  
Vol 10 (2) ◽  
pp. 235
Author(s):  
Fitria Mustika ◽  
Tengku Muhammad Sahudra
Keyword(s):  
Family Environment ◽  
High Frequency ◽  
Low Frequency ◽  
Measurement Scale ◽  
Education Student ◽  
Achievement Level ◽  
Very High Frequency ◽  
Environmental Care ◽  
The Family

This study aims to determine the role of the family, community, and tertiary environment towards the formation of caring character in the geography education student environment. The output of this study was a four-indexed indexed education journal and a UNIMED google scolar. Samples from the study population were 20 respondents with 30 items about questionnaires. The time of the study starts from May 2018 to October 2018. The measurement scale in this study is the scale of the briquette. Data collection by means of library studies, interviews, questionnaires, and documentation. This research was conducted by distributing questionnaire questionnaires and interviews. Based on the results of questionnaire data processing, the family environment has a very high frequency in the formation of character of the student's environmental care with an achievement level of a total score of 91%. Furthermore, the role of the campus environment also has a high frequency in the formation of the character of the student's environmental care with a total score of 89%. Whereas the family environment has a low frequency in the formation of character of student environmental care with a total score of 57%. It can be concluded that the family environment has the most role in forming the character of the student's environmental care.

Role of secretin and CCK in the stimulation of pancreatic secretion in conscious dogs. Effects of atropine and somatostatin

1987 ◽  
Vol 2 (4) ◽  
pp. 223-235
Author(s):  
Stanislaw J. Konturek ◽  
JanW Konturek ◽  
Cornelis B. Lamers ◽  
Janine Tasler ◽  
Jan Bilski
Keyword(s):  
Pancreatic Secretion ◽  
Conscious Dogs ◽  
Stimulation Of
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