The gross morphology and histochemistry of respiratory muscles in bottlenose dolphins, Tursiops truncatus

126

We measured esophageal pressures, respiratory flow rates, and expired O 2 and CO 2 in six adult bottlenose dolphins (Tursiops truncatus) during voluntary breaths and maximal (chuff ) respiratory efforts. The data were used to estimate the dynamic specific lung compliance (sC L ), the O 2 consumption rate (V O2 ) and CO 2 production rates (V CO2 ) during rest. ). The average estimated V O2 and V CO2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O 2 min −1 and 0.589 to 0.851 l CO 2 min, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. In addition, our custom-made system allows us to approximate end tidal gas composition. Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.

Section: Discussionmentioning

confidence: 88%

Lung mechanics and pulmonary function testing in cetaceans

Fahlman

Loring

Levine³

et al. 2015

126

“…For example, it has been suggested that the diaphragm and intercostal muscles are important to generate high respiratory flow and rapid f R (Ridgway, 1972;Dearolf, 2003;Cotten et al, 2008). However, few studies have compared the functional properties within and between species.…”

Section: Respiratory Mechanics: Flow and Compliancementioning

confidence: 99%

Respiratory function and mechanics in pinnipeds and cetaceans

Fahlman

Moore

García-Párraga

2017

In this Review, we focus on the functional properties of the respiratory system of pinnipeds and cetaceans, and briefly summarize the underlying anatomy; in doing so, we provide an overview of what is currently known about their respiratory physiology and mechanics. While exposure to high pressure is a common challenge among breath-hold divers, there is a large variation in respiratory anatomy, function and capacity between species -how are these traits adapted to allow the animals to withstand the physiological challenges faced during dives? The ultra-deep diving feats of some marine mammals defy our current understanding of respiratory physiology and lung mechanics. These animals cope daily with lung compression, alveolar collapse, transient hyperoxia and extreme hypoxia. By improving our understanding of respiratory physiology under these conditions, we will be better able to define the physiological constraints imposed on these animals, and how these limitations may affect the survival of marine mammals in a changing environment. Many of the respiratory traits to survive exposure to an extreme environment may inspire novel treatments for a variety of respiratory problems in humans.

“…Dearolf et al, 2000;Etnier et al, 2004;Cotten et al, 2008;Kielhorn et al, 2013), were used. Approximately 1cm 3 blocks of m. longissimus dorsi were cut from a position just ventral to the superficial tendon (Pabst, 1990), coated with Optimal Cutting Temperature compound (Sakura Finekek, Torrance, CA, USA), rapidly frozen in isopentane cooled by liquid nitrogen, and sectioned at 10μm thickness in a cryostat (Leica Microsystems, Wetzlar, Germany) at −19°C.…”

Section: Muscle Histochemistry and Fiber Diametermentioning

confidence: 99%

Novel locomotor muscle design in extreme deep-diving whales

Velten

Dillaman

Kinsey

et al. 2013

Self Cite

SUMMARYMost marine mammals are hypothesized to routinely dive within their aerobic dive limit (ADL). Mammals that regularly perform deep, long-duration dives have locomotor muscles with elevated myoglobin concentrations that are composed of predominantly large, slow-twitch (Type I) fibers with low mitochondrial volume densities (V mt ). These features contribute to extending ADL by increasing oxygen stores and decreasing metabolic rate. Recent tagging studies, however, have challenged the view that two groups of extreme deep-diving cetaceans dive within their ADLs. Beaked whales (including Ziphius cavirostris and Mesoplodon densirostris) routinely perform the deepest and longest average dives of any air-breathing vertebrate, and short-finned pilot whales (Globicephala macrorhynchus) perform high-speed sprints at depth. We investigated the locomotor muscle morphology and estimated total body oxygen stores of several species within these two groups of cetaceans to determine whether they (1) shared muscle design features with other deep divers and (2) performed dives within their calculated ADLs. Muscle of both cetaceans displayed high myoglobin concentrations and large fibers, as predicted, but novel fiber profiles for diving mammals. Beaked whales possessed a sprinterʼs fiber-type profile, composed of ~80% fast-twitch (Type II) fibers with low V mt . Approximately one-third of the muscle fibers of short-finned pilot whales were slow-twitch, oxidative, glycolytic fibers, a rare fiber type for any mammal. The muscle morphology of beaked whales likely decreases the energetic cost of diving, while that of short-finned pilot whales supports high activity events. Calculated ADLs indicate that, at low metabolic rates, both beaked and short-finned pilot whales carry sufficient onboard oxygen to aerobically support their dives. Supplementary material available online at