A Physio-Logging Journey: Heart Rates of the Emperor Penguin and Blue Whale

Ponganis, Paul J.

doi:10.3389/fphys.2021.721381

Cited by 5 publications

(3 citation statements)

References 101 publications

(134 reference statements)

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“…We recently demonstrated the utility of CW-NIRS in voluntarily diving seals and breath-hold diving humans performing deep dives (>100 m) ( McKnight et al, 2019 , 2021a , b ). Thus, this technology promises to open new avenues for physiological research in free-ranging animals, as highlighted in a number of recent physio-logging reviews ( Fahlman et al, 2021a ; Ponganis, 2021 ; Williams et al, 2021 ; Williams and Hindle, 2021 ; Williams and Ponganis, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Near-Infrared Spectroscopy as a Tool for Marine Mammal Research and Care

Ruesch

McKnight

Fahlman³

et al. 2022

Front. Physiol.

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Developments in wearable human medical and sports health trackers has offered new solutions to challenges encountered by eco-physiologists attempting to measure physiological attributes in freely moving animals. Near-infrared spectroscopy (NIRS) is one such solution that has potential as a powerful physio-logging tool to assess physiology in freely moving animals. NIRS is a non-invasive optics-based technology, that uses non-ionizing radiation to illuminate biological tissue and measures changes in oxygenated and deoxygenated hemoglobin concentrations inside tissues such as skin, muscle, and the brain. The overall footprint of the device is small enough to be deployed in wearable physio-logging devices. We show that changes in hemoglobin concentration can be recorded from bottlenose dolphins and gray seals with signal quality comparable to that achieved in human recordings. We further discuss functionality, benefits, and limitations of NIRS as a standard tool for animal care and wildlife tracking for the marine mammal research community.

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Section: Introductionmentioning

confidence: 99%

Near-Infrared Spectroscopy as a Tool for Marine Mammal Research and Care

Ruesch

McKnight

Fahlman³

et al. 2022

Front. Physiol.

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“…The larger diameter purkinje fibres gave recovery times of order 2000 ms. All these values could be compared with resting and exercising heart rates amongst mammalian species. For example, resting heart rates of blue whale ∼30; elephant, ∼30; human, ∼70; mouse, ∼650; shrew, ∼835, Etruscan shrew, ∼1,511 bpm, correspond to cardiac cycle durations of ∼2000, ∼2000, ∼850, ∼90, ∼70 and ∼40 ms respectively ( Benedict and Lee, 1936 ; Fons et al, 1997 ; Ho et al, 2011 ; Goldbogen et al, 2019 ; Ponganis, 2021 ). Electrodiffusion could thus potentially either entirely, or partially but significantly, account for such recovery in atrial and ventricular cardiomyocytes respectively, to extents dependent on the species heart rates.…”

Section: Discussionmentioning

confidence: 99%

Nernst-Planck-Gaussian modelling of electrodiffusional recovery from ephaptic excitation between mammalian cardiomyocytes

Morris,

Bardsley,

Salvage

et al. 2024

Front. Physiol.

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Introduction: In addition to gap junction conduction, recent reports implicate possible ephaptic coupling contributions to action potential (AP) propagation between successive adjacent cardiomyocytes. Here, AP generation in an active cell, withdraws Na+ from, creating a negative potential within, ephaptic spaces between the participating membranes, activating the initially quiescent neighbouring cardiomyocyte. However, sustainable ephaptic transmission requires subsequent complete recovery of the ephaptic charge difference. We explore physical contributions of passive electrodiffusive ion exchange with the remaining extracellular space to this recovery for the first time.Materials and Methods: Computational, finite element, analysis examined limiting, temporal and spatial, ephaptic [Na+], [Cl−], and the consequent Gaussian charge differences and membrane potential recovery patterns following a ΔV∼130 mV AP upstroke at physiological (37°C) temperatures. This incorporated Nernst-Planck formalisms into equations for the time-dependent spatial concentration gradient profiles.Results: Mammalian atrial, ventricular and purkinje cardiomyocyte ephaptic junctions were modelled by closely apposed circularly symmetric membranes, specific capacitance 1 μF cm-2, experimentally reported radii a = 8,000, 12,000 and 40,000 nm respectively and ephaptic axial distance w = 20 nm. This enclosed an ephaptic space containing principal ions initially at normal extracellular [Na+] = 153.1 mM and [Cl−] = 145.8 mM, respective diffusion coefficients DNa = 1.3 × 109 and DCl = 2 × 109 nm2s-1. Stable, concordant computational solutions were confirmed exploring ≤1,600 nm mesh sizes and Δt≤0.08 ms stepsize intervals. The corresponding membrane voltage profile changes across the initially quiescent membrane were obtainable from computed, graphically represented a and w-dependent ionic concentration differences adapting Gauss’s flux theorem. Further simulations explored biological variations in ephaptic dimensions, membrane anatomy, and diffusion restrictions within the ephaptic space. Atrial, ventricular and Purkinje cardiomyocytes gave 40, 180 and 2000 ms 99.9% recovery times, with 720 or 360 ms high limits from doubling ventricular radius or halving diffusion coefficient. Varying a, and DNa and DCl markedly affected recovery time-courses with logarithmic and double-logarithmic relationships, Varying w exerted minimal effects.Conclusion: We thereby characterise the properties of, and through comparing atrial, ventricular and purkinje recovery times with interspecies in vivo background cardiac cycle duration data, (blue whale ∼2000, human∼90, Etruscan shrew, ∼40 ms) can determine physical limits to, electrodiffusive contributions to ephaptic recovery.

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“…Research on cetaceans found that when whales dive, they can reduce their heart rate (bradycardia) to 4–8 beats per minute (bpm) and increase it to 40 bpm at the surface (tachycardia) [ 43 ]. Emperor penguins have a similar diving response, where their heart rate is reduced to 5–10 bpm at the bottom of the ocean, from 200–240 bpm at the sea surface [ 44 ]. Since blood pressure is associated with elevated IOP in humans, this might be one of the possible mechanisms in marine mammals and seabirds to reduce IOP while diving underwater with a high atmospheric pressure.…”

Section: Discussionmentioning

confidence: 99%

Glaucoma through Animal’s Eyes: Insights from the Evolution of Intraocular Pressure in Mammals and Birds

Hongjamrassilp

Zhang

Natterson-Horowitz

et al. 2022

Animals

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Glaucoma, an eye disorder caused by elevated intraocular pressure (IOP), is the leading cause of irreversible blindness in humans. Understanding how IOP levels have evolved across animal species could shed light on the nature of human vulnerability to glaucoma. Here, we studied the evolution of IOP in mammals and birds and explored its life history correlates. We conducted a systematic review, to create a dataset of species-specific IOP levels and reconstructed the ancestral states of IOP using three models of evolution (Brownian, Early burst, and Ornstein–Uhlenbeck (OU)) to understand the evolution of glaucoma. Furthermore, we tested the association between life history traits (e.g., body mass, blood pressure, diet, longevity, and habitat) and IOP using phylogenetic generalized least squares (PGLS). IOP in mammals and birds evolved under the OU model, suggesting stabilizing selection toward an optimal value. Larger mammals had higher IOPs and aquatic birds had higher IOPs; no other measured life history traits, the type of tonometer used, or whether the animal was sedated when measuring IOP explained the significant variation in IOP in this dataset. Elevated IOP, which could result from physiological and anatomical processes, evolved multiple times in mammals and birds. However, we do not understand how species with high IOP avoid glaucoma. While we found very few associations between life history traits and IOP, we suggest that more detailed studies may help identify mechanisms by which IOP is decoupled from glaucoma. Importantly, species with higher IOPs (cetaceans, pinnipeds, and rhinoceros) could be good model systems for studying glaucoma-resistant adaptations.

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A Physio-Logging Journey: Heart Rates of the Emperor Penguin and Blue Whale

Cited by 5 publications

References 101 publications

Near-Infrared Spectroscopy as a Tool for Marine Mammal Research and Care

Near-Infrared Spectroscopy as a Tool for Marine Mammal Research and Care

Nernst-Planck-Gaussian modelling of electrodiffusional recovery from ephaptic excitation between mammalian cardiomyocytes

Glaucoma through Animal’s Eyes: Insights from the Evolution of Intraocular Pressure in Mammals and Birds

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