Physiology of Diving in Marine Mammals

Kooyman, Gerald L.; Castellini, Michael A.; Davis, R. W.

doi:10.1146/annurev.ph.43.030181.002015

Cited by 164 publications

(104 citation statements)

References 24 publications

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“…in flippers) could make a match of Q 10 values advantageous in diving mammals. Information on body temperature in diving mammals is limited, but core temperature can decrease by 2-3°C (Kooyman et al, 1981) and occasionally even up to 7°C (Meir and Ponganis, 2010) in diving seals. A decrease in body temperature would help to reduce metabolic rate (and thus O 2 demand), but it appears that core temperature is relatively tightly controlled during routine dives and is only allowed to decrease appreciably during exceptional long dives (Meir and Ponganis, 2010).…”

Section: Rbc Anion Exchangementioning

confidence: 99%

Respiratory properties of blood in the harbor porpoise,Phocoena phocoena

Soegaard

Hansen

Elk

et al. 2012

Journal of Experimental Biology

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SUMMARYHarbor porpoises are active divers that exchange O 2 and CO 2 with the environment during a fast single breath upon surfacing. We investigated blood O 2 -transporting properties, buffer characteristics, Cl -transport via the erythrocyte anion exchanger (AE1), circulating nitric oxide metabolites and hemoglobin nitrite reduction in harbor porpoises with the aim to evaluate traits that are adaptive for diving behavior. Blood O 2 affinity was higher in harbor porpoises than in similar sized terrestrial mammals, as supported by our parallel recordings of O 2 equilibria in sheep and pig blood. Further, O 2 affinity tended to increase with increasing body mass. A high O 2 affinity favors O 2 extraction from the lungs, but a normal Bohr effect (logP 50 /pH-0.46) gradually lowers O 2 affinity during dives (where CO 2 accumulates) to assist O 2 off-loading to perfused tissues. The true plasma non-bicarbonate buffer value was moderately higher than in terrestrial mammals and increased upon deoxygenation. Plasma bicarbonate was also relatively high, contributing to increase the overall buffer capacity. The apparent Cl -permeability of harbor porpoise erythrocytes was similar to the human value at 37°C, showing absence of a comparative increase in the velocity of erythrocyte HCO 3 -/Cl -exchange to aid CO 2 excretion. The Q 10 for AE1-mediated Cl -transport in harbor porpoises was lower than in humans and seemed to match the Q 10 for metabolism (Q 10 Ϸ2). Plasma nitrite, plasma nitrate and hemoglobin-mediated nitrite reduction were elevated compared with mammalian standards, suggesting that increased nitric oxide bioavailability and nitrite-derived nitric oxide could play important roles in diving physiology.

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Section: Rbc Anion Exchangementioning

confidence: 99%

Respiratory properties of blood in the harbor porpoise,Phocoena phocoena

Soegaard

Hansen

Elk

et al. 2012

Journal of Experimental Biology

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“…These animals can make dives more than 1800m deep with durations exceeding 90min (Kooyman et al, 1981;Watwood et al, 2006). The thick blubber layer that surrounds the body can comprise more than 30% of body mass (see Koopman, 2007;Pond, 1998), which for a human diver would be considered high risk.…”

Section: Introductionmentioning

confidence: 99%

Solubility of nitrogen in marine mammal blubber depends on its lipid composition

Koopman

Westgate

2012

Journal of Experimental Biology

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SUMMARYUnderstanding the solubility of nitrogen gas in tissues is a crucial aspect of diving physiology, especially for air-breathing tetrapods. Adipose tissue is of particular interest because of the high solubility of nitrogen in lipids. Surprisingly, nothing is known about nitrogen solubility in the blubber of any marine mammal. We tested the hypothesis that N 2 solubility is dependent on the lipid composition of blubber; most blubber is composed of triacylglycerols, but some toothed whales deposit large amounts of waxes in blubber instead. The solubility of N 2 in the blubber of 13 toothed whale species ranged from 0.062 to 0.107ml N 2 ml -1 oil. Blubber with high wax ester content had higher N 2 solubility, observed in the beaked (Ziphiidae) and small sperm (Kogiidae) whales, animals that routinely make long, deep dives. We also measured nitrogen solubility in the specialized cranial acoustic fat bodies associated with echolocation in a Rissoʼs dolphin; values (0.087ml N 2 ml -1 oil) were 16% higher here than in its blubber (0.074ml N 2 ml -1 oil). As the acoustic fats of all Odontocetes contain waxes, even if the blubber does not, these tissues may experience greater interaction with N 2 . These data have implications for our understanding and future modeling of diving physiology in Odontocetes, as our empirically derived values for nitrogen solubility in toothed whale adipose were up to 40% higher than the numbers traditionally assumed in marine mammal diving models.

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“…Jg,2s Only the brain maintains a normal or increased blood supply. 9,27 The diving reflex may have clinical importance. Death from arrhythmias due to the oculocardiac reflex are well known.…”

Section: Discussionmentioning

confidence: 99%

Bradycardia during cold ocular irrigation under general anaesthesia: an example of the diving reflex

Arndt¹,

Stock

1993

Can J Anaesth

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The oculocardiac reflex, well-described in the anaesthesia literature, results from a variety of stimuli including traction on the extraocular muscles, ocular manipulation, pressure or traction on the globe, or pressure applied to an empty orbit. I-5 However, even in the absence of these stimuli, cold ocular irrigation may elicit bradycardia induced by the diving reflex. The oculocardiac reflex is active in awake and anaesthetized subjects and is manifested by a variety of dysrhythmias, which include bradycardia, bigeminy, ectopic beats, nodal rhythm, and asystole. 6-8 The diving reflex may have similar physiological mechanisms and clinical significance. Key wordsHEART: alThythmia; BRADYCARDIA: diving reflex. Accepted for publication 22nd February, 1993.Case report A 60-yr-old woman was scheduled for left scleral buckle. Her past medical history was unremarkable, with no history of cardiovascular, neurological, renal, haematopoetic, endocrinological, or pulmonary disease. She did not smoke or use alcohol or take medications. Previously she had undergone two gynaecological operations during uncomplicated general anaesthesia. Physical examination was normal and there was no syncopal history. The preoperative laboratory results were normal, with haemoglobin and haematocrit 13.7 gin. dl -I and 39.7%, respectively. The preoperative 12-lead electrocardiograph (ECG) showed normal sinus rhythm with no suggestion of ischaemia. The vital signs the day before surgery were blood pressure 140/80 mmHg, pulse 88 beats, min -I and respirations 18 breaths, min -x. She weighed 55.7 kg and was 155 cm tall. Sixty minutes before her operation, the patient received diazepam I0 mg po, and a peripheral /v infusion of lactated Ringer's solution with 5% dextrose.Intraoperative monitoring included a fivedead continuous ECG which displayed limb lead II. After preoxygenation, anaesthesia was induced with thiopentone 275 mg and lidocaine 100 mg /v. Tracheal intubation was facilitated with succinylcholine 80 mg/v, and was easily accomplished. Anaesthesia was maintained with 1% isoflurane and 50% nitrous oxide in oxygen. Ventilation was controlled so that end-tidal carbon dioxide concentration was 36 mmHg. Relaxation was maintained with 5 mg /v vecuronium bromide. Vital signs did not vary by more than 5% during anaesthetic induction and maintenance up to this point.Fifteen minutes after induction, a watertight drape was placed around the left eye and the surgeon began to irrigate the eye liberally with sterile, room-temperature, normal saline. The temperature of the saline was 19.7~ The heart rate promptly decreased from 78 beats, min -1 with normal sinus rhythm to a sinus bradycardia of 30 beats, min-l. The surgeon stopped the irrigation and atropine 0.4 mg was given/v. The heart rate increased to 90 beats-min -I with normal sinus rhythm. The episode CAN J ANAESTH 1993 / 40:6 / pp511-4

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Physiology of Diving in Marine Mammals

Cited by 164 publications

References 24 publications

Respiratory properties of blood in the harbor porpoise,Phocoena phocoena

Respiratory properties of blood in the harbor porpoise,Phocoena phocoena

Solubility of nitrogen in marine mammal blubber depends on its lipid composition

Bradycardia during cold ocular irrigation under general anaesthesia: an example of the diving reflex

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