Pharmacological blockade of the dive response: effects on heart rate and diving behaviour in the harbour seal (Phoca vitulina)

SUMMARYWhile diving, harbour seals (Phoca vitulina) manage their oxygen stores through cardiovascular adjustments, including bradycardia, a concurrent reduction in cardiac output, and peripheral vasoconstriction. At the surface,post-dive tachycardia facilitates rapid reloading of oxygen stores. Although harbour seals can tolerate >20 min of submergence, the majority of their natural dives are only 2-6 min and are usually followed by surface intervals that are <1 min, so they spend approximately 80% of their time submerged. Given that harbour seals meet their ecological needs through repetitive short aerobic dives, we were interested in the functional role, if any, of the dive response during these short dives. During voluntary diving in an 11 m deep tank, the cardiovascular responses to submergence of five harbour seals were manipulated using specific pharmacological antagonists, and the effects on diving behaviour were observed. Effects of pharmacological blockade on heart rate were also examined to assess the autonomic control of heart rate during voluntary diving. Heart rate was recorded using subcutaneous electrodes and data loggers, while diving behaviour was monitored using a video camera. The muscarinic blocker methoctramine blocked diving bradycardia, theα-adrenergic blocker prazosin blocked diving vasoconstriction, and theβ-adrenergic blocker metoprolol blocked post-dive tachycardia. Heart-rate analysis indicated that diving bradycardia is primarily modulated by the vagus, while post-dive tachycardia results from parasympathetic withdrawal as well as increased sympathetic stimulation of the heart. None of the pharmacological blockers had any effect on average dive or surface interval duration. Seals maintained a high percentage of time spent diving in all treatments. Thus, harbour seals do not appear to need the dive response during short dives in order to maintain an efficient dive strategy.

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Effect of pharmacological blockade on cardiovascular responses to voluntary and forced diving in muskrats.

Journal of Experimental Biology ◽

10.1242/jeb.198.11.2307 ◽

1995 ◽

Vol 198 (11) ◽

pp. 2307-2315 ◽

Cited By ~ 5

Author(s):

P E Signore ◽

D R Jones

Keyword(s):

Heart Rate ◽

Neural Control ◽

Peripheral Resistance ◽

Cardiovascular Responses ◽

Adrenergic Blocker ◽

Adrenergic Blockers ◽

Pharmacological Blockade ◽

Parasympathetic Influences ◽

Neural Effect

Neural control of free and forced diving bradycardia and peripheral resistance was studied in the muskrat (Ondatra zibethicus) by means of acute pharmacological blockade with the muscarinic blocker atropine, the alpha-adrenergic blocker phentolamine and the beta-adrenergic blockers nadolol and propranolol. Saline injection was used as a control. Heart rate in control animals increased before voluntary dives and dropped markedly as soon as the animals submerged. Heart rate started increasing towards the end of voluntary dives and reached pre-dive values within the first 5 s of recovery. Pre-dive and post-dive tachycardia were reduced in beta-blocked animals, emphasizing the role of the sympathetic system during the preparatory and recovery periods of voluntary dives. Diving bradycardia and the acceleration in heart rate before surfacing were abolished by atropine and unaffected by nadolol, demonstrating the importance of vagal efferent activity during diving. The results after blockade with nadolol suggest that there is an accentuated antagonism between the two branches of the autonomic nervous system during diving, so that parasympathetic influences on the heart predominate. Propranolol-treated muskrats had a higher diving heart rate than saline- and nadolol-treated animals, which may be due to a sedative effect caused by propranolol crossing the blood-brain barrier, a blockade of central catecholaminergic pathways or a peripheral neural effect, due to the anaesthetic properties of propranolol. Phentolamine did not affect diving bradycardia, indicating that diving bradycardia occurs independently of peripheral vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)

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Diving Heart Rate Development in Postnatal Harbour Seals, Phoca vitulina

Physiological and Biochemical Zoology ◽

10.1086/425201 ◽

2005 ◽

Vol 78 (1) ◽

pp. 9-17 ◽

Cited By ~ 25

Author(s):

Danielle K. Greaves ◽

Jason F. Schreer ◽

Michael O. Hammill ◽

Jennifer M. Burns

Keyword(s):

Heart Rate ◽

Phoca Vitulina ◽

Harbour Seals ◽

Rate Development

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Maintenance of Blood Pressure in Emotional Context-based Autonomic Switching by the Central Nucleus of the Amygdala in Rats

10.21203/rs.3.rs-109253/v1 ◽

2020 ◽

Author(s):

Ko Yamanaka ◽

Hidefumi Waki

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Pressor Response ◽

Cardiovascular Responses ◽

Central Nucleus ◽

Emotional Context ◽

Neuronal Mechanisms ◽

Pressor Responses ◽

Pharmacological Blockade ◽

Aversive Classical Conditioning

Abstract Proper autonomic control is necessary in making appropriate decisions and actions, but neuronal mechanisms for this function are yet to be determined. Here we show that the amygdala plays a role in autonomic cardiovascular tuning in a dynamically changing environment. We recorded blood pressure and heart rate of head-restrained rats during appetitive and aversive classical conditioning tasks. Rats learned varying associations between conditioned stimuli and unconditioned stimuli in three types of contexts: appetitive, neutral, and aversive blocks. Blood pressure and heart rate in the appetitive block gradually increased after reward-predicting cues, followed by a vigorously increased response to the actual reward. The predictive response was found to be significantly higher than the responses in the neutral and aversive blocks. Blood pressure and heart rate responses to the air puff-predicting cue in the aversive block were significantly lower than that of the responses in the neutral block. Pharmacological blockade of the amygdala has significantly decreased reward-predictive pressor responses in the latter phase, but not in the initial phase of context change. Cardiovascular responses are thus adaptively tuned by positive and negative emotional stimuli, and the central nucleus of the amygdala likely assists in maintaining pressor response tuning based on emotional context.

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Testing predictions of optimal diving theory using animal-borne video from harbour seals (Phoca vitulina concolor)

Canadian Journal of Zoology ◽

10.1139/cjz-2013-0137 ◽

2014 ◽

Vol 92 (4) ◽

pp. 309-318 ◽

Cited By ~ 15

Author(s):

Susan G. Heaslip ◽

W. Don Bowen ◽

Sara J. Iverson

Keyword(s):

Nova Scotia ◽

Temporal Pattern ◽

Dive Depth ◽

Dive Duration ◽

Phoca Vitulina ◽

Encounter Rate ◽

Harbour Seals ◽

Wide Range ◽

Oxygen Stores ◽

Free Ranging

Optimal diving theory predicts that animals make decisions that maximize their foraging profitability subject to the constraint of oxygen stores. We examined the temporal pattern of prey encounters within a dive from concurrently collected dive data and animal-borne video from a free-ranging pinniped to test predictions of optimal diving theory. Crittercams were deployed on 32 adult male harbour seals (Phoca vitulina concolor De Kay, 1842) at Sable Island, Nova Scotia, Canada, for 3 days each. Deployments resulted in approximately 3 h of video per seal and a total of 2275 capture attempts for 1474 prey encounter events recorded. We found support for seven of the nine selected predictions of optimal diving theory. As predicted, prey encounters increased with bottom duration; dive duration increased with dive depth; and travel duration, bottom duration, and percent bottom duration decreased over a wide range of travel durations. Descent duration did increase with dive depth, and seals terminated dives earlier when no prey were encountered and when prey were encountered later in a dive. Contrary to prediction, bottom duration did not increase and then decrease for short travel durations and dives were not terminated earlier when travel durations were short and prey encounter rate was low.

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Diving behaviour of lactating harbour seals and their pups during maternal foraging trips

Canadian Journal of Zoology ◽

10.1139/z99-065 ◽

1999 ◽

Vol 77 (6) ◽

pp. 978-988 ◽

Cited By ~ 54

Author(s):

W D Bowen ◽

D J Boness ◽

S J Iverson

Keyword(s):

Nova Scotia ◽

Post Partum ◽

Dive Duration ◽

Phoca Vitulina ◽

Diving Behaviour ◽

Early Lactation ◽

Adult Females ◽

Harbour Seals ◽

Lactating Females

Female harbour seals (Phoca vitulina) undertake foraging trips during mid to late lactation. We show that they are accompanied by their pup during many of these foraging trips. Time-depth recorder data were obtained from 20 lactating females and 14 of their pups in 1995 and 1996 at Sable Island, Nova Scotia. Overall, females spent 55.4 ± 4.68% (mean ± SE) of their time at sea compared with 39.8 ± 2.29% for pups. Like those of their mothers, pups' dives occurred in clusters or bouts: 71.4 ± 4.4 dives, 2.5 ± 0.15 h in duration. Bouts of diving by females and pups began 0-3 days post partum. Mean dive duration of pups increased from about 1 to 1.5 min over the course of lactation, but was still shorter than that of adult females (1.5-2.25 min). Both females and pups appeared to dive within their theoretical aerobic dive limits (TADL) of 8.9 and 2.6-3.1 min, respectively. Up to 3.6% of dives by some pups may have exceeded their TADL. Pups appeared to compensate for their lesser diving ability by making more and shorter dives per bout than females, particularly during early lactation.

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Diving behaviour of sub-adult harbour seals (Phoca vitulina) at Prins Karls Forland, Svalbard

Polar Biology ◽

10.1007/s00300-001-0330-2 ◽

2002 ◽

Vol 25 (3) ◽

pp. 230-234 ◽

Cited By ~ 10

Author(s):

Bjørn A. Krafft ◽

Christian Lydersen ◽

Ian Gjertz ◽

Kit M. Kovacs

Keyword(s):

Phoca Vitulina ◽

Diving Behaviour ◽

Harbour Seals

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A Review of Deep Learning-Based Contactless Heart Rate Measurement Methods

Sensors ◽

10.3390/s21113719 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3719

Author(s):

Aoxin Ni ◽

Arian Azarang ◽

Nasser Kehtarnavaz

Keyword(s):

Heart Rate ◽

Deep Learning ◽

Mean Absolute Error ◽

Absolute Error ◽

Video Camera ◽

Measurement Methods ◽

Rate Measurement ◽

Learning Methods ◽

The Public ◽

Heart Rate Measurement

The interest in contactless or remote heart rate measurement has been steadily growing in healthcare and sports applications. Contactless methods involve the utilization of a video camera and image processing algorithms. Recently, deep learning methods have been used to improve the performance of conventional contactless methods for heart rate measurement. After providing a review of the related literature, a comparison of the deep learning methods whose codes are publicly available is conducted in this paper. The public domain UBFC dataset is used to compare the performance of these deep learning methods for heart rate measurement. The results obtained show that the deep learning method PhysNet generates the best heart rate measurement outcome among these methods, with a mean absolute error value of 2.57 beats per minute and a mean square error value of 7.56 beats per minute.

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Cardiovascular Responses to Muscle Stretching: A Systematic Review and Meta-analysis

International Journal of Sports Medicine ◽

10.1055/a-1312-7131 ◽

2021 ◽

Author(s):

Ewan Thomas ◽

Marianna Bellafiore ◽

Ambra Gentile ◽

Antonio Paoli ◽

Antonio Palma ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cardiovascular System ◽

Vascular Function ◽

Meta Analysis ◽

Random Effect ◽

Cardiovascular Responses ◽

Qualitative Description ◽

Cross Sectional ◽

Quantitative Synthesis

AbstractThe aim of this study will be to review the current body of literature to understand the effects of stretching on the responses of the cardiovascular system. A literature search was performed using the following databases: Scopus, NLM Pubmed and ScienceDirect. Studies regarding the effects of stretching on responses of the cardiovascular system were investigated. Outcomes regarded heart rate(HR), blood pressure, pulse wave velocity (PWV of which baPWV for brachial-ankle and cfPWV for carotid-femoral waveforms), heart rate variability and endothelial vascular function. Subsequently, the effects of each outcome were quantitatively synthetized using meta-analytic synthesis with random-effect models. A total of 16 studies were considered eligible and included in the quantitative synthesis. Groups were also stratified according to cross-sectional or longitudinal stretching interventions. Quality assessment through the NHLBI tools observed a “fair-to-good” quality of the studies. The meta-analytic synthesis showed a significant effect of d=0.38 concerning HR, d=2.04 regarding baPWV and d=0.46 for cfPWV. Stretching significantly reduces arterial stiffness and HR. The qualitative description of the studies was also supported by the meta-analytic synthesis. No adverse effects were reported, after stretching, in patients affected by cardiovascular disease on blood pressure. There is a lack of studies regarding vascular adaptations to stretching.

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