Respiration in the African Lungfish Protopterus Aethiopicus

1968 ◽  
Vol 49 (2) ◽  
pp. 453-468
Author(s):  
KJELL JOHANSEN ◽  
CLAUDE LENFANT
Keyword(s):  
Regional Blood Flow ◽  
Air Exposure ◽  
Lung Inflation ◽  
Air Breathing ◽  
Pulmonary Flow ◽  
Hypoxic Water ◽  
African Lungfish ◽  
Systemic Arteries ◽  
Arterial Po2 ◽  
Protopterus Aethiopicus

1. Factors controlling aerial and aquatic breathing have been studied in the intact, free-swimming African lungfish, Protopterus aethiopicus. Frequencies of aerial and branchial breathing were correlated with gas tensions in the lung and in blood from pulmonary and systemic arteries and veins. 2. Studies were made, on fish resting in aerated water, during exposure to air and during hypoxic and hypercarbic conditions in the environment. 3. Both branchial and pulmonary breathing were irregular during rest in aerated water. The rate of branchial breathing normally exceeded that of air breathing. An increased rate and vigour of branchial breathing commonly preceded an air breath. There was no indication that a new air breath was related to the values of arterial Po2 and pH. 4. Air exposure elicited a marked and immediate increase in the rate of air breathing. Hypoxic water never evoked any compensatory breathing responses while breathing from a hypoxic gas mixture quickly increased the rate of air breathing. Bubbling 5% CO2 in air into the aquarium caused a reduction in branchial breathing while the rate of air breathing increased. 5. Nicotine injected intravenously or in the water close to the gills elicited an increase in both aerial and branchial breathing. 6. Respiratory and circulatory events were correlated during undisturbed breathing and during artificial lung inflation. Increased cardiac output and a shift in regional blood flow to a higher pulmonary flow occurred with air breaths.

Respiration in the African Lungfish Protopterus Aethiopicus

1968 ◽  
Vol 49 (2) ◽  
pp. 437-452 ◽  
Author(s):  
CLAUDE LENFANT ◽  
KJELL JOHANSEN
Keyword(s):  
Gas Exchange ◽  
Haemoglobin Concentration ◽  
Temperature Shift ◽  
Mean Value ◽  
Gas Analysis ◽  
Air Exposure ◽  
Air Breathing ◽  
African Lungfish ◽  
High Degree ◽  
Protopterus Aethiopicus

1. Respiratory properties of blood and pattern of aerial and aquatic breathing and gas exchange have been studied in the African lungfish, Protopterus aethiopicus. 2. The mean value for haematocrit was 25%. Haemoglobin concentration was 6.2 g% and O2 capacity 6.8 vol. %. 3. The affinity of haemoglobin for O2 was high. P50 was 10 mm. Hg at PCOCO2, 6 mm. Hg and 25 °C. The Bohr effect was smaller than for the Australian lungfish, Neoceratodus, but exceeded that for the South American lungfish, Lepidosiren. The O2 affinity showed a larger temperature shift in Protopterus than Neoceratodus. 4. The CO2 combining power and the over-all buffering capacity of the blood exceeded values for the other lungfishes. 5. Both aerial and aquatic breathing showed a labile frequency. Air exposure elicited a marked increase in the rate of air breathing. 6. When resting in aerated water, air breathing accounted for about 90% of the O2 absorption. Aquatic gas exchange with gills and skin was 2.5 times more effective than pulmonary gas exchange in removing CO2. The low gas-exchange ratio for the lung diminished further in the interval between breaths. 7. Protopterus showed respiratory independence and a maintained O2 uptake until the ambient O2 and CO2 tensions were 85 and 35 mm. Hg respectively. A further reduction in O2 tension caused an abrupt fall in the oxygen uptake. 8. Gas analysis of blood samples drawn from unanaesthetized, free-swimming fishes attested to the important role of the lung in gas exchange and the high degree of functional separation in the circulation of oxygenated and deoxygenated blood.

Spontaneous spermatocytic seminoma in African lungfish, Protopterus aethiopicus Heckel

1984 ◽  
Vol 7 (2) ◽  
pp. 169-172 ◽  
Author(s):  
PRINCE MASAHITO ◽  
T. ISHIKAWA ◽  
S. TAKAYAMA
Keyword(s):  
Spermatocytic Seminoma ◽  
African Lungfish ◽  
Protopterus Aethiopicus

Effect of combined recompression and air, oxygen, or heliox breathing on air bubbles in rat tissues

2001 ◽  
Vol 90 (5) ◽  
pp. 1639-1647 ◽  
Author(s):  
O. Hyldegaard ◽  
D. Kerem ◽  
Y. Melamed
Keyword(s):  
Adipose Tissue ◽  
White Matter ◽  
Decompression Sickness ◽  
Rat Tissues ◽  
Air Bubbles ◽  
Transient Growth ◽  
Air Exposure ◽  
Air Breathing ◽  
Oxygen Breathing ◽  
Clinical Observations

The fate of bubbles formed in tissues during the ascent from a real or simulated air dive and subjected to therapeutic recompression has only been indirectly inferred from theoretical modeling and clinical observations. We visually followed the resolution of micro air bubbles injected into adipose tissue, spinal white matter, muscle, and tendon of anesthetized rats recompressed to and held at 284 kPa while rats breathed air, oxygen, heliox 80:20, or heliox 50:50. The rats underwent a prolonged hyperbaric air exposure before bubble injection and recompression. In all tissues, bubbles disappeared faster during breathing of oxygen or heliox mixtures than during air breathing. In some of the experiments, oxygen breathing caused a transient growth of the bubbles. In spinal white matter, heliox 50:50 or oxygen breathing resulted in significantly faster bubble resolution than did heliox 80:20 breathing. In conclusion, air bubbles in lipid and aqueous tissues shrink and disappear faster during recompression during breathing of heliox mixtures or oxygen compared with air breathing. The clinical implication of these findings might be that heliox 50:50 is the mixture of choice for the treatment of decompression sickness.

scholarly journals Maximal exercise at extreme altitudes on Mount Everest

1983 ◽  
Vol 55 (3) ◽  
pp. 688-698 ◽  
Author(s):  
J. B. West ◽  
S. J. Boyer ◽  
D. J. Graber ◽  
P. H. Hackett ◽  
K. H. Maret ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Maximal Exercise ◽  
Ambient Air ◽  
O2 Uptake ◽  
Mount Everest ◽  
Air Breathing ◽  
Co2 Partial Pressure ◽  
O2 Partial Pressure ◽  
Low Levels ◽  
Arterial Po2

Maximal exercise at extreme altitudes was studied during the course of the American Medical Research Expedition to Everest. Measurements were carried out at sea level [inspired O2 partial pressure (PO2) 147 Torr], 6,300 m during air breathing (inspired PO2 64 Torr), 6,300 m during 16% O2 breathing (inspired PO2 49 Torr), and 6,300 m during 14% O2 breathing (inspired PO2 43 Torr). The last PO2 is equivalent to that on the summit of Mt. Everest. All the 6,300 m studies were carried out in a warm well-equipped laboratory on well-acclimatized subjects. Maximal O2 uptake fell dramatically as the inspired PO2 was reduced to very low levels. However, two subjects were able to reach an O2 uptake of 1 l/min at the lowest inspired PO2. Arterial O2 saturations fell markedly and alveolar-arterial PO2 differences increased as the work rate was raised at high altitude, indicating diffusion limitation of O2 transfer. Maximal exercise ventilations exceeded 200 l/min at 6,300 m during air breathing but fell considerably at the lowest values of inspired PO2. Alveolar CO2 partial pressure was reduced to 7-8 Torr in one subject at the lowest inspired PO2, and the same value was obtained from alveolar gas samples taken by him at rest on the summit. The results help to explain how man can reach the highest point on earth while breathing ambient air.

Regional distribution of blood flow in awake heat-stressed baboons

1979 ◽  
Vol 237 (6) ◽  
pp. H705-H712 ◽  
Author(s):  
J. R. Hales ◽  
L. B. Rowell ◽  
R. B. King
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Renal Vasoconstriction ◽  
Suitable Animal Model ◽  
Mean Pressure ◽  
Subcutaneous Adipose ◽  
Arterial Po2 ◽  
The Brain

Radioactive microspheres (containing six different nuclide labels) were used to measure blood flow (BF) to most major organs of eight conscious baboons during heat stress. Cardiac output (CO), arterial mean pressure, and arterial PO2, PCO2, and pH did not change, but heart rate increased and stroke volume fell as body temperature increased by as much as 2.56 degrees C. Skin BF increased in all regions sampled so that the fraction of CO distributed to skin (not including feet and hands) increased from 3% (control) to 14%. Increased skin BF was compensated for by decreases in splanchnic (intestines, stomach, pancreas, and spleen) (35%), renal (27%), and possibly muscle BF. There was no change in BF to the brain, spinal cord, coronary, or subcutaneous adipose tissue during heating. Therefore, baboons show a generalized redistribution of BF during heat stress, so that increments in skin BF are provided without increases in CO, whereas man depends on changes in both; despite this latter difference between the baboon and man, the similarity in magnitude of the splanchnic and renal vasoconstriction between the two primates may indicate that the baboon would be a suitable animal model for investigations into mechanisms of changes in regional blood flow in man during heat stress.

Myocardial and systemic responses to arterial hypoxemia during cardiac tamponade

1989 ◽  
Vol 257 (3) ◽  
pp. H726-H733
Author(s):  
G. J. Crystal ◽  
M. R. Salem
Keyword(s):  
Cardiac Tamponade ◽  
Regional Blood Flow ◽  
Aortic Pressure ◽  
Arterial Hypoxemia ◽  
Pericardial Pressure ◽  
O2 Supply ◽  
Fick Equation ◽  
Arterial Po2 ◽  
Mean Aortic Pressure ◽  
Systemic Responses

Experiments were performed on 14 anesthetized, open-chest dogs to assess myocardial and systemic responses to cardiac tamponade alone (TAMP) and combined with arterial hypoxemia (HYP). Regional blood flow (RBF) was measured with radioactive microspheres and used to compute regional O2 supply. Myocardial oxygen and lactate extraction were determined. Myocardial oxygen consumption (MVO2) was calculated with Fick equation. An increase in pericardial pressure, sufficient to reduce mean aortic pressure (MAP) by 20%, caused proportional decreases in myocardial RBF and MVO2 but had no effect on endo-to-epi flow ratio or on myocardial lactate extraction. TAMP alone decreased RBF and O2 supply in kidney, splanchnic organs, skeletal muscle, and skin, but it had no effect in brain. HYP (arterial PO2, 35 +/- 2 mmHg) during TAMP restored MAP and caused transmurally uniform increases in myocardial RBF that were adequate to maintain MVO2 and lactate extraction. RBF increased sufficiently in brain to maintain regional O2 supply, whereas unchanged or inadequate increases in RBF in other tissues accentuated reductions in O2 supply. During combined TAMP and HYP, local vasodilator mechanisms were capable of maintaining adequate oxygen supply in myocardium and brain but not apparently in the nonvital tissues where these mechanisms were antagonized by reflex vasoconstriction.

Circulatory adaptation to bimodal respiration in the dipnoan lungfish

1985 ◽  
Vol 59 (2) ◽  
pp. 285-294 ◽  
Author(s):  
A. P. Fishman ◽  
R. G. DeLaney ◽  
P. Laurent
Keyword(s):  
Pulmonary Artery ◽  
Prostaglandin E2 ◽  
Ductus Arteriosus ◽  
Nerve Fibers ◽  
Beta Agonist ◽  
Air Breathing ◽  
Granular Vesicle ◽  
Ductus Arteriosus Botalli ◽  
Protopterus Aethiopicus

In the dipnoan lungfish, Protopterus aethiopicus, P. annectens, and Lepidosiren paradoxa, the ductus is a short powerful muscular vascular trunk forming a channel for communication between the systemic and pulmonary circulations. In structure, the dipnoan ductus is very similar to the ductus arteriosus (Botalli) in the mammal. Innervation is abundant, consisting of myelinated and nonmyelinated nerve fibers issuing, at least in part, from the vagus. Neurons are present in the adventitia, and numerous nerve profiles, filled with small agranular vesicles, are closely associated with the myocytes, suggesting strong cholinergic control. Perfusion of the ductus in vitro using hypoxic saline causes it to dilate; conversely it is constricted by alpha-agonists. Dopamine and prostaglandin E2 are potent dilators, whereas the beta-agonist, isoproterenol, and acetylcholine are less powerful. A vasomotor segment has been identified on the pulmonary artery (PAVS) close to its junction with the ductus. Its location and structure are similar to the corresponding segment in amphibians and reptiles. It is innervated by endings filled with small clear vesicles. Granular vesicle cells are also present within the adventitia. The PAVS is constricted by acetylcholine. As in amphibians, alpha-agonists and hypoxic saline are without vasomotor effects. Based on the anatomic and physiological observations, a concept of cyclic perfusion of the gas exchangers in Dipnoi is proposed. During the alternation between air breathing (emersion) and apneic phases (immersion), the pattern of the circulation in the lungfish oscillates between that of a tetrapod and a fish.

scholarly journals Ontogenetic development of the gastrointestinal tract of African lungfish larvae Protopterus aethiopicus (Heckel 1851): A light microscopy study

2020 ◽  
Vol 51 (12) ◽  
pp. 5074-5083
Author(s):  
Martin Sserwadda ◽  
Nancy Nevejan ◽  
Ronald Ntanzi ◽  
Pieter Cornillie ◽  
Wim Van den Broeck ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Light Microscopy ◽  
Microscopy Study ◽  
Ontogenetic Development ◽  
African Lungfish ◽  
Protopterus Aethiopicus
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