Unsteady-state gas exchange and storage in diving marine mammals: the harbor porpoise and gray seal

2001 ◽  
Vol 281 (2) ◽  
pp. R490-R494 ◽  
Author(s):  
R. G. Boutilier ◽  
J. Z. Reed ◽  
M. A. Fedak
Keyword(s):  
Gas Exchange ◽  
Marine Mammals ◽  
Lung Ventilation ◽  
The Body ◽  
Breath Hold ◽  
Unsteady State ◽  
Harbor Porpoise ◽  
Per Se ◽  
End Tidal ◽  
And Storage

Breath-by-breath measurements of end-tidal O2 and CO2 concentrations in harbor porpoise reveal that the respiratory gas exchange ratio (RR; CO2 output/O2 uptake) of the first lung ventilation in a breathing bout after a prolonged breath-hold is always well below the animal's metabolic respiratory quotient (RQ) of 0.85. Thus the longest apneic pauses are always followed by an initial breath having a very low RR(0.6–0.7), which thereafter increases with each subsequent breath to values in excess of 1.2. Although the O2 stores of the body are fully readjusted after the first three to four breaths following a prolonged apneic pause, a further three to four ventilations are always needed, not to load more O2 but to eliminate built-up levels of CO2. The slower readjustment of CO2 stores relates to their greater magnitude and to the fact that they must be mobilized from comparatively large and chemically complex HCO[Formula: see text]/CO2 stores that are built up in the blood and tissues during the breath-hold. These data, and similar measurements on gray seals (12), indicate that it is the readjustment of metabolic RQ and not O2 stores per se that governs the amount of time an animal must spend ventilating at the surface after a dive.

Gas Exchange and Ventilatory Responses to Hypoxia and Hypercapnia in Amphisbaena Alba (Reptilia: Amphisbaenia)

1987 ◽  
Vol 127 (1) ◽  
pp. 159-172 ◽  
Author(s):  
AUGUSTO S. ABE ◽  
KJELL JOHANSEN
Keyword(s):  
Gas Exchange ◽  
Oxygen Uptake ◽  
Large Fraction ◽  
Breath Hold ◽  
Low Oxygen ◽  
Hold Period ◽  
Ventilatory Responses ◽  
Variable Duration ◽  
End Tidal ◽  
A Minor

1. Total and cutaneous gas exchange and ventilatory responses to breathing hypoxic and hypercapnic gases were studied in Amphisbaena alba (Linnaeus), a burrowing squamate reptile. 2. This species shows a very low oxygen uptake rate (VO2) compared with other squamates of the same size (VO2 = 15.4, 36.2 and 49.0 mlkg−1 h−1 at 20, 25 and 30°C, respectively). Cutaneous gas exchange represents a large fraction of the total uptake. Oxygen uptake was strongly affected by temperature [Q10 = 5.5 (20–25°C); 1.8 (25–30°C); 3.2 (20–30°C)]. 3. A. alba shows a biphasic ventilatory pattern under hypoxic and hypercapnic conditions. A single breathing cycle, consisting of expiration-inspiration, includes a ventilatory period (VP) followed by a non-ventilatory (breath hold) period (NVP) of variable duration. When breathing air at 25°C the NVP typically occupied about 2 min. The ventilatory period occupied only 0.075 parts of a complete breath-tobreath cycle. Breathing hypoxic gases caused a pronounced rise in ventilation volume (Ve) from an increase in tidal volume (Vt) and frequency (f) at inspired O2 concentrations below 7%. Breathing hypercapnic gas mixtures induced a minor change in Vt at CO2 concentrations below 3%, and Ve increased mostly because of increases in f. End tidal O2 (PetOO2) and CO2 (PetOO2) tensions changed with increasing VE while breathing hypoxic and hypercapnic gas. 4. The results are discussed in relation to the fossorial habits of A. alba, and are compared with data from other squamates.

Control of arrhythmic breathing in bimodal breathers: Amphibia

1988 ◽  
Vol 66 (1) ◽  
pp. 6-19 ◽  
Author(s):  
Robert G. Boutilier
Keyword(s):  
Control System ◽  
Gas Exchange ◽  
Lung Ventilation ◽  
Breath Holding ◽  
Breath Hold ◽  
Breathing Patterns ◽  
Gas Exchanges ◽  
Air Breathing ◽  
Activity State ◽  
Breath Pattern

Amphibians employ a system of gas exchange whereby various combinations of the lungs, gills, and skin are used to exploit gas exchanges in both air and water (bimodal breathing). Continuous lung ventilation is rarely observed in these animals. Instead, the dominant breath pattern is arrhythmic in nature and is believed to have evolved in response to a periodic need to supplement aquatic gas exchange. Such a need is largely dependent on the activity state of the animal concerned and its capacity for aquatic gas exchange. The overall control system appears to be one that turns lung ventilation on and off by trigger signals arising from chemo- and mechano-sensitive receptors responding to changing conditions during periods of breath holding and breathing. In amphibians in which the aquatic exchanger is a major avenue for CO2 elimination, [Formula: see text] levels in the lungs and blood do not change substantially in the latter stages of a breath hold. Under these conditions falling levels of oxygen may be the primary stimulus to terminate the breath hold and initiate breathing. There is, however, some interaction between the two gases since elevated CO2 levels affect the sensitivity of the predominantly O2-mediated response. Another major component in determining air-breathing patterns in these animals is their ability to delay the onset of breathing when certain behavioural activities take precedence over the need for additional gas exchange.

scholarly journals Pulmonary ventilation–perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the bends

2018 ◽  
Vol 285 (1877) ◽  
pp. 20180482 ◽  
Author(s):  
Daniel Garcia Párraga ◽  
Michael Moore ◽  
Andreas Fahlman
Keyword(s):  
Gas Exchange ◽  
Marine Mammals ◽  
Decompression Sickness ◽  
Large Fraction ◽  
Pulmonary Ventilation ◽  
Flow Distribution ◽  
Theoretical Modelling ◽  
Breath Hold ◽  
Air Breathing ◽  
Marine Vertebrates

Hydrostatic lung compression in diving marine mammals, with collapsing alveoli blocking gas exchange at depth, has been the main theoretical basis for limiting N 2 uptake and avoiding gas emboli (GE) as they ascend. However, studies of beached and bycaught cetaceans and sea turtles imply that air-breathing marine vertebrates may, under unusual circumstances, develop GE that result in decompression sickness (DCS) symptoms. Theoretical modelling of tissue and blood gas dynamics of breath-hold divers suggests that changes in perfusion and blood flow distribution may also play a significant role. The results from the modelling work suggest that our current understanding of diving physiology in many species is poor, as the models predict blood and tissue N 2 levels that would result in severe DCS symptoms (chokes, paralysis and death) in a large fraction of natural dive profiles. In this review, we combine published results from marine mammals and turtles to propose alternative mechanisms for how marine vertebrates control gas exchange in the lung, through management of the pulmonary distribution of alveolar ventilation ( ) and cardiac output/lung perfusion ( ), varying the level of in different regions of the lung. Man-made disturbances, causing stress, could alter the mismatch level in the lung, resulting in an abnormally elevated uptake of N 2 , increasing the risk for GE. Our hypothesis provides avenues for new areas of research, offers an explanation for how sonar exposure may alter physiology causing GE and provides a new mechanism for how air-breathing marine vertebrates usually avoid the diving-related problems observed in human divers.

Alveolar gas exchange during breath-hold diving

1963 ◽  
Vol 18 (3) ◽  
pp. 471-477 ◽  
Author(s):  
E. H. Lanphier ◽  
H. Rahn
Keyword(s):  
Gas Exchange ◽  
Sea Water ◽  
Ambient Pressure ◽  
Acute Hypoxia ◽  
Normal Subjects ◽  
The Body ◽  
Breath Holding ◽  
Breath Hold ◽  
October 17 ◽  
Alveolar Gas Exchange

Use of a recompression chamber permitted simulation of breath-hold dives to 33 ft of sea water (2 atm abs). Four normal subjects made such dives during rest and mild exertion while delivering alveolar gas samples at frequent intervals by a partial-rebreathing procedure. The course of alveolar gas exchange differed greatly from that in ordinary breath holding. Oxygen uptake remained at near normal levels until ascent owing to the maintenance of alveolar Po2 by increased ambient pressure. Reversal of CO2 transfer occurred during descent, and little CO2 moved in the normal direction until ascent. Greater uptake of oxygen and retention of CO2 in the body led to lower final values of both alveolar Po2 and Pco2 than in comparable breath holding at the surface. Hyperventilation made possible longer dives with harder work, and in these the Po2 reached very low values on ascent. One subject showed a final Po2 of 24 mm Hg with evidence of reversed O2 transfer. Acute hypoxia on ascent is a likely cause of drowning in breath-hold diving. Submitted on October 17, 1962

scholarly journals Staphylococcus-associated acute glomerulonephritis in a patient with dermatomyositis

2021 ◽  
Vol 14 (1) ◽  
pp. e236695 ◽  
Author(s):  
Rasmi Ranjan Sahoo ◽  
Sourav Pradhan ◽  
Akhil Pawan Goel ◽  
Anupam Wakhlu
Keyword(s):  
Infective Endocarditis ◽  
Kidney Biopsy ◽  
Kidney Injury ◽  
Staphylococcal Infection ◽  
Left Knee ◽  
The Body ◽  
Acute Glomerulonephritis ◽  
Disease Course ◽  
Rheumatological Disease ◽  
Per Se

Staphylococcus-associated glomerulonephritis (SAGN) occurs as a complication of staphylococcal infection elsewhere in the body. Dermatomyositis (DM) can be associated with glomerulonephritis due to the disease per se. We report a case of a 40-year-old male patient with DM who presented with acute kidney injury, and was initially pulsed with methylprednisolone for 3 days, followed by dexamethasone equivalent to 1 mg/kg/day prednisolone. He was subsequently found to have SAGN on kidney biopsy along with staphylococcus bacteraemia and left knee septic arthritis. With proof of definitive infection, intravenous immunoglobulin 2 g/kg over 2 days was given and steroids were reduced. He was treated with intravenous vancomycin. With treatment, the general condition of the patient improved. On day 38, he developed infective endocarditis and died of congestive heart failure subsequently. Undiagnosed staphylococcal sepsis complicating a rheumatological disease course can lead to complications like SAGN, infective endocarditis and contribute to increased morbidity and mortality, as is exemplified by our case.

Metabolic adjustments to breath holding in higher vertebrates

1989 ◽  
Vol 67 (12) ◽  
pp. 3024-3031 ◽  
Author(s):  
P. J. Butler
Keyword(s):  
Marine Mammals ◽  
Lactate Production ◽  
Weddell Seal ◽  
Specific Dynamic Action ◽  
The Body ◽  
Breath Holding ◽  
Reduced Body ◽  
Key Factor ◽  
Reduced Rate ◽  
Anaerobic Production

There is substantial behavioural and physiological evidence to suggest that most feeding dives by aquatic birds and mammals are aerobic in nature, with no net production of lactate. Any increase in lactate production is matched by increased removal. This does not mean, however, that there are no cardiovascular adjustments associated with such dives. Nonactive parts of the body (including the large pectoral muscles in diving ducks) may be hypoperfused and consume oxygen at a reduced rate. For example, in marine mammals, such as the Weddell seal, reduced perfusion of the gut during a feeding period (which can last for up to 12 h) would reduce the energy expenditure associated with the digestion and assimilation of food (specific dynamic action). Reperfusion during the nonfeeding period would contribute to an unusually high "resting" oxygen uptake. Although some tissues in seals at least can tolerate periods of ischaemia, there is no evidence to suggest that enhanced anaerobic production of ATP is a key factor in the survival of marine mammals during unusually long periods underwater. There may, in fact, be an overall reduction in the ATP requirements of certain tissues, possibly as a result of a reduction in the permeability of cell membranes to some ions, but most certainly as a result of reduced body temperature. During relatively long dives, lactate production eventually exceeds its rate of removal and it accumulates. Precisely what occurs in the muscles is not known. One suggestion is that periods of vasoconstriction are interrupted by vasodilatation, when the oxygen stores are replaced.

Antioxidants Reverse Reduction of the Human Hypoxic Ventilatory Response by Subanesthetic Isoflurane

2005 ◽  
Vol 102 (4) ◽  
pp. 747-753 ◽  
Author(s):  
Luc J. Teppema ◽  
Raymonda R. Romberg ◽  
Albert Dahan
Keyword(s):  
Redox State ◽  
Direct Action ◽  
Upper Airway ◽  
The Body ◽  
Alpha Tocopherol ◽  
Hypoxic Response ◽  
Carotid Bodies ◽  
Intravenous Ascorbic Acid ◽  
End Tidal ◽  
Control Sham

Background In subanesthetic concentrations, volatile anesthetics reduce the acute hypoxic response (AHR), presumably by a direct action on the carotid bodies but by an unknown molecular mechanism. To examine a possible involvement of reactive oxygen species or changes in redox state in this inhibiting effect, the authors studied the effect of antioxidants on the isoflurane-induced reduction of the AHR in humans. Methods In 10 volunteers, the authors studied the effect of antioxidants (intravenous ascorbic acid and oral alpha-tocopherol) on the reduction by isoflurane (0.12% end-tidal concentration) of the AHR on a 3-min isocapnic hypoxic stimulus (hemoglobin oxygen saturation 86 +/- 4%). All subjects participated in three separate sessions in which the effects of the antioxidants (session 1), placebo (session 2), and sham isoflurane plus antioxidants (session 3) were tested on the (sham) isoflurane-induced effect on the AHR. Results Isoflurane reduced the acute hypoxic response from 0.82 +/- 0.41 l . min . % to 0.49 +/- 0.23 l . min . % and from 0.89 +/- 0.43 l . min . % to 0.48 +/- 0.28 l . min . % in sessions 1 and 2, respectively (mean +/- SD; P < 0.05 vs. control). This reduction of the AHR was completely reversed by antioxidants (AHR = 0.76 +/- 0.39 l . min . %; not significantly different from control, session 1) but not by placebo in session 2 (AHR = 0.50 +/- 0.30 l . min . %; P < 005 vs. control). Sham isoflurane or antioxidants per se had no effect on the hypoxic response. Conclusions The data indicate that isoflurane may depress the AHR by influencing the redox state of oxygen-sensing elements in the carotid bodies. This finding may have clinical implications for patients who are prone to recurrent hypoxic episodes, e.g., due to upper airway obstruction, in the postoperative period when low-dose isoflurane may persist in the body for some time.

Concentration and Visualization Techniques in Buddhist Meditation

2021 ◽  
Author(s):  
Nobuyoshi Yamabe
Keyword(s):  
Fifth Century ◽  
The Body ◽  
Early Form ◽  
Significant Development ◽  
Buddhist Meditation ◽  
Esoteric Buddhism ◽  
Reflective Thought ◽  
Visual Approach ◽  
Per Se ◽  
Visualization Techniques

This chapter outlines the early form and development of Buddhist meditation. First, it discusses the “application of mindfulness,” especially “mindfulness of the body,” which can be largely classified into two types of practice. One is “mindfulness per se,” without reflective thought, and the other is a more reflective or visual approach. “Mindfulness per se” (in particular, mindful breathing) was transmitted to East Asia and remains the cardinal method there. The chapter discusses close ties between traditional mindfulness and Japanese Sōtō practice. It then moves on to describe meditation on the decomposition of a corpse, which is a representative form of the more reflective and visual type of practice, involving the observation of a dead body in its stages of decomposition. This is found in early scriptures. Later texts came to teach a more elaborate method of “grasping the images” of a corpse. A notable development in visualization is that the images seen by the practitioner came to include ones that were more enigmatic. The discussion finally turns to another significant development in Buddhist meditation, one which involves Buddha visualization. Its undeveloped form is found in early Mahayana sutras, but a fully developed version employing statues as aides for visualization is found in later meditation texts from the fifth century onward. This type of visualization was inherited by Esoteric Buddhism and is still practiced today.

scholarly journals Cleaner birds: an overview for the Neotropics

2010 ◽  
Vol 10 (4) ◽  
pp. 195-203 ◽  
Author(s):  
Ivan Sazima ◽  
Cristina Sazima
Keyword(s):  
Marine Mammals ◽  
Bird Species ◽  
The Body ◽  
Domestic Dog ◽  
Large Herbivores ◽  
Broad Category ◽  
Organic Debris ◽  
Marine Reptiles ◽  
Black Vulture ◽  
Do So

Several bird species feed on a variety of external parasites and epibionts, organic debris, dead and wounded tissue, clots and blood, and secretions from the body of other vertebrates (hosts or clients). We present an overview of so called cleaner birds from the Neotropics based on field records, literature, and photo survey. We found that 33 bird species in 16 families practice cleaning even if some of them do so very occasionally. The birds range from the Galápagos ground finch Geospiza fuliginosa to the widespread black vulture Coragyps atratus. Clients mostly are large herbivores such as capybaras, deer, and livestock, but also include medium-sized herbivores such as iguanas and tortoises, and carnivores such as boobies and seals - a few bird species associate with these latter marine mammals. No carnivorous terrestrial mammal client is recorded to date except for a domestic dog, from whose hair black vultures picked organic debris. Some clients adopt particular inviting postures while being cleaned, whereas others are indifferent or even disturbed by the activity of cleaner birds. Capybaras, giant tortoises, and iguanas are among the inviting clients, whereas boobies try to dislodge the 'vampire' finch Geospiza difficilis. Most of the Neotropical cleaner birds may be lumped in one broad category (omnivores that dwell in open areas and associate with large to medium-sized herbivores). A second, restricted category accommodates some species from Patagonia and the Galápagos Islands (omnivores that dwell in open areas and associate with carnivorous marine mammals, or seabirds and marine reptiles). Two still more restricted categories accommodate the following: 1) forest-dwelling cleaner birds; and 2) marine coastal cleaners. Additional records of Neotropical cleaner birds will mostly fall in the broad category.

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