The heart rate - breathing rate relationship in aquatic mammals: A comparative analysis with terrestrial species

Abstract Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency (f) by comparison to terrestrial mammals of the same body size, the difference increasing the larger the species. Among various interpretations, it was suggested that the low-f breathing is a consequence of the end-inspiratory breath-holding pattern adopted by aquatic mammals to favour buoyancy at the water surface, and evolved to be part of the genetic makeup. If this interpretation was correct it could be expected that, differently from f, the heart rate (HR, beats/min) of aquatic and semi-aquatic mammals at rest would not need to differ from that of terrestrial mammals and that their HR-f ratio would be higher than in terrestrial species. Literature data for HR (beats/min) in mammals at rest were gathered for 56 terrestrial and 27 aquatic species. In aquatic mammals the allometric curve (HR=191·M-0.18; M= body mass, kg) did not differ from that of terrestrial species (HR=212·M-0.22) and their HR-f ratio (on average 32±5) was much higher than in terrestrial species (5±1) (P<0.0001). The comparison of these HR allometric curves to those for f previously published indicated that the HR-f ratio was body size-independent in terrestrial species while it increased significantly with M in aquatic species. The similarity in HR and differences in f between aquatic and terrestrial mammals agree with the possibility that the low f of aquatic and semi-aquatic mammals may have evolved for a non-respiratory function, namely the regulation of buoyancy at the water surface.

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Estimation of Delay Times in Coupling Between Autonomic Regulatory Loops of Human Heart Rate and Blood Flow Using Phase Dynamics Analysis

The Open Hypertension Journal ◽

10.2174/1876526201709010016 ◽

2017 ◽

Vol 9 (1) ◽

pp. 16-22 ◽

Cited By ~ 1

Author(s):

Vladimir S Khorev ◽

Anatoly S Karavaev ◽

Elena E Lapsheva ◽

Tatyana A Galushko ◽

Mikhail D Prokhorov ◽

...

Keyword(s):

Heart Rate ◽

Delay Time ◽

Healthy Subjects ◽

Low Frequency ◽

Phase Dynamics ◽

Oscillatory Systems ◽

Low Frequency Oscillations ◽

Delay Times ◽

The Difference ◽

Regulatory Loop

Objective: We assessed the delay times in the interaction between the autonomic regulatory loop of Heart Rate Variability (HRV) and autonomic regulatory loop of photoplethysmographic waveform variability (PPGV), showing low-frequency oscillations. Material and Methods: In eight healthy subjects aged 25–30 years (3 male, 5 female), we studied at rest (in a supine position) the simultaneously recorded two-hour signals of RR intervals (RRIs) chain and finger photoplethysmogram (PPG). To extract the low-frequency components of RRIs and PPG signal, associated with the low-frequency oscillations in HRV and PPGV with a frequency of about 0.1 Hz, we filtered RRIs and PPG with a bandpass 0.05-0.15 Hz filter. We used a method for the detection of coupling between oscillatory systems, based on the construction of predictive models of instantaneous phase dynamics, for the estimation of delay times in the interaction between the studied regulatory loops. Results: Averaged value of delay time in coupling from the regulatory loop of HRV to the loop of PPGV was 0.9±0.4 seconds (mean ± standard error of the means) and averaged value of delay time in coupling from PPGV to HRV was 4.1±1.1 seconds. Conclusion: Analysis of two-hour experimental time series of healthy subjects revealed the presence of delay times in the interaction between regulatory loops of HRV and PPGV. Estimated delay time in coupling regulatory loops from HRV to PPGV was about one second or even less, while the delay time in coupling from PPGV to HRV was about several seconds. The difference in delay times is explained by the fact that PPGV to HRV response is mediated through the autonomic nervous system (baroreflex), while the HRV to PPGV response is mediated mechanically via cardiac output.

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Effect of Losartan, an Angiotensin II Type 1 Receptor Antagonist on Cardiac Autonomic Functions of Rats During Acute and Chronic Inhibition of Nitric Oxide Synthesis

Physiological Research ◽

10.33549/physiolres.932243 ◽

2012 ◽

pp. 135-144

Author(s):

M. CHASWAL ◽

S. DAS ◽

J. PRASAD ◽

A. KATYAL ◽

A. K. MISHRA ◽

...

Keyword(s):

Nitric Oxide ◽

Heart Rate ◽

High Frequency ◽

Spectral Power ◽

Pressor Response ◽

Low Frequency ◽

Renin Angiotensin System ◽

Nitric Oxide Synthesis ◽

Total Spectral Power ◽

The Difference

We studied the effect of losartan on baroreflex sensitivity (BRS) and heart rate variability (HRV) of adult Wistar rats during acute and chronic inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME). Chronic L-NAME administration (50 mg/kg per day for 7 days, orally through gavage) increased mean arterial pressure (MAP), heart rate but significantly decreased BRS. In addition, a significant fall of standard deviation of normal RR intervals, total spectral power, high frequency spectral power and a rise of low frequency to high frequency (LF: HF) ratio was seen. Acute L-NAME administration (30 mg/kg, i.v. bolus dose) also raised MAP and impaired HRV but it was associated with augmented BRS for bradycardia reflex. Losartan treatment (10 mg/kg, i.v.) in both acute and chronic L-NAME treated rats, decreased MAP but the difference was not significant. On the other hand, losartan administration normalized depressed BRS for bradycardia reflex and significantly reduced LF to HF ratio in chronic L-NAME treated rats. But this improvement was not observed in acute L-NAME group. These results indicate importance of mechanisms other than renin-angiotensin system in the pressor response of both acute as well as chronic L-NAME. However, autonomic dysregulation especially following chronic L-NAME appears to be partly angiotensin dependent.

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Heart Rate Variability: Rescaling and Normalization

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.g5896.059720 ◽

2020 ◽

Vol 9 (7) ◽

pp. 1073-1078

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

High Frequency ◽

Low Frequency ◽

Clinical Applications ◽

Average Heart Rate ◽

Psychological Conditions ◽

Hrv Analysis ◽

The Difference ◽

The Individual

Heart rate variability (HRV) is a useful measure to evaluate activity of the autonomic nervous system (ANS) and monitor both pathological and psychological conditions. However, HRV analysis still has difficulties with changes in HRV parameters due to an increase or decrease in the average heart rate. At present, the interpretation of the average changes in HRV datasets and their HRV parameters is not fully understood. Therefore, this study aimed to analyze how much deviation in HRV parameters occurs from rescaling tachograms and normalizing HRV datasets. Four rescaled tachograms and their corresponding normalized HRV datasets were created by increasing the average heartbeat from 50 to 110 bpm in 20 bpm steps. The difference in low frequency powers (Ln LFs) calculated between two successive rescaled groups was 0.89, 1.03, and 1.04, as the average heartbeat increased from slow to fast, while the difference in high frequency powers (Ln HFs) was 1.06, 1.53, and 1.37. However, in the four normalized HRV datasets, the difference in Ln LFs and Ln HFs between two successive normalized groups was -0.28 and -0.12, 0.31 and 0.27, and 0.31 and 0.37, respectively. The results suggest that the normalized HRV datasets are more valuable than the individual rescaled-tachogram HRV dataset for obtaining measurements using frequency-domain HRV parameters for HRV analysis in clinical applications.

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Seasonal body size reductions with warming covary with major body size gradients in arthropod species

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.0238 ◽

2017 ◽

Vol 284 (1851) ◽

pp. 20170238 ◽

Cited By ~ 29

Author(s):

Curtis R. Horne ◽

Andrew G. Hirst ◽

David Atkinson

Keyword(s):

Body Size ◽

Size Variation ◽

Seasonal Temperature ◽

Adult Size ◽

Aquatic Species ◽

Terrestrial Species ◽

Total Percentage ◽

Arthropod Species ◽

Seasonal Temperature Variation ◽

Developmental Conditions

Major biological and biogeographical rules link body size variation with latitude or environmental temperature, and these rules are often studied in isolation. Within multivoltine species, seasonal temperature variation can cause substantial changes in adult body size, as subsequent generations experience different developmental conditions. Yet, unlike other size patterns, these common seasonal temperature–size gradients have never been collectively analysed. We undertake the largest analysis to date of seasonal temperature-size gradients in multivoltine arthropods, including 102 aquatic and terrestrial species from 71 global locations. Adult size declines in warmer seasons in 86% of the species examined. Aquatic species show approximately 2.5-fold greater reduction in size per °C of warming than terrestrial species, supporting the hypothesis that greater oxygen limitation in water than in air forces aquatic species to exhibit greater plasticity in body size with temperature. Total percentage change in size over the annual cycle appears relatively constant with annual temperature range but varies between environments, such that the overall size reduction in aquatic-developing species (approx. 31%) is almost threefold greater than in terrestrial species (approx. 11%). For the first time, we show that strong correlations exist between seasonal temperature–size gradients, laboratory responses and latitudinal–size clines, suggesting that these patterns share common drivers.

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Heart Rate Variability, Emotions, and Music

Journal of Psychophysiology ◽

10.1027/0269-8803/a000021 ◽

2010 ◽

Vol 24 (2) ◽

pp. 112-119 ◽

Cited By ~ 9

Author(s):

F. Riganello ◽

A. Candelieri ◽

M. Quintieri ◽

G. Dolce

Keyword(s):

Data Mining ◽

Heart Rate ◽

Heart Rate Variability ◽

Vegetative State ◽

Low Frequency ◽

Emotional Reactions ◽

Heart Beat ◽

Healthy Controls ◽

Frequency Spectra ◽

Emotional Value

The purpose of the study was to identify significant changes in heart rate variability (an emerging descriptor of emotional conditions; HRV) concomitant to complex auditory stimuli with emotional value (music). In healthy controls, traumatic brain injured (TBI) patients, and subjects in the vegetative state (VS) the heart beat was continuously recorded while the subjects were passively listening to each of four music samples of different authorship. The heart rate (parametric and nonparametric) frequency spectra were computed and the spectra descriptors were processed by data-mining procedures. Data-mining sorted the nu_lf (normalized parameter unit of the spectrum low frequency range) as the significant descriptor by which the healthy controls, TBI patients, and VS subjects’ HRV responses to music could be clustered in classes matching those defined by the controls and TBI patients’ subjective reports. These findings promote the potential for HRV to reflect complex emotional stimuli and suggest that residual emotional reactions continue to occur in VS. HRV descriptors and data-mining appear applicable in brain function research in the absence of consciousness.

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The Effects of a Caffeine Placebo and Experimenter Expectation on Blood Pressure, Heart Rate, Well-Being, and Cognitive Performance

European Psychologist ◽

10.1027//1016-9040.6.1.15 ◽

2001 ◽

Vol 6 (1) ◽

pp. 15-25 ◽

Cited By ~ 18

Author(s):

Harald Walach ◽

Stefan Schmidt ◽

Yvonne-Michelle Bihr ◽

Susanne Wiesch

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cognitive Task ◽

Well Being ◽

Control Group ◽

Double Blind ◽

Main Effect ◽

The Difference ◽

Being There ◽

To Receive

We studied the effect of experimenter expectations and different instructions in a balanced placebo design. 157 subjects were randomized into a 2 × 4 factorial design. Two experimenters were led to expect placebos either to produce physiological effects or not (pro- vs. antiplacebo). All subjects except a control group received a caffeine placebo. They were either made to expect coffee, no coffee, or were in a double-blind condition. Dependent measures were blood pressure, heart rate, well-being, and a cognitive task. There was one main effect on the instruction factor (p = 0.03) with the group “told no caffeine” reporting significantly better well-being. There was one main effect on the experimenter factor with subjects instructed by experimenter “proplacebo” having higher systolic blood pressure (p = 0.008). There was one interaction with subjects instructed by experimenter “proplacebo” to receive coffee doing worse in the cognitive task than the rest. Subjects instructed by experimenter “antiplacebo” were significantly less likely to believe the experimental instruction, and that mostly if they had been instructed to receive coffee. Contrary to the literature we could not show an effect of instruction, but there was an effect of experimenters. It is likely, however, that these experimenter effects were not due to experimental manipulations, but to the difference in personalities.

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