Cardio-respiratory ontogeny during chronic carbon monoxide exposure in the clawed frog Xenopus laevis.

1998 ◽  
Vol 201 (9) ◽  
pp. 1461-1472 ◽  
Author(s):  
P R Territo ◽  
W W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Xenopus Laevis ◽  
Lactate Concentration ◽  
Respiratory Physiology ◽  
Whole Body ◽  
O2 Transport ◽  
Rate Of Oxygen Consumption ◽  
Stage 1 ◽  
Clawed Frog ◽  
Individual Mass

The present study investigates the ontogeny of cardio-respiratory physiology in Xenopus laevis where O2 transport is obstructed. Animals were raised from eggs (NF stage 1) to metamorphic climax (NF stage 63), while maintained either in air or in chronic 2 kPa CO, which functionally ablates O2 transport by hemoglobin (Hb). Whole-animal rate of oxygen consumption (.MO2), whole-body lactate concentration, individual mass, heart rate (fh) and stroke volume (Vs) were measured. Additionally, cardiac output (.Q) and the ratio of the rate of oxygen consumption to the total rate at which oxygen is transported in the blood (.MO2/.QO2) were calculated to determine limitations imparted when O2 transport is impaired. Our data on early development suggest that the onset of convective blood flow occurs prior to the absolute need for convection to supplement diffusive transport. Values for .MO2, whole-body lactate concentration, mass and fh did not differ significantly between controls and CO-exposed animals. However, CO-exposed animals showed a significant (P<0.05) increase in Vs, .MO2/.QO2 and .Q compared with controls. These results indicate that limiting blood O2 transport is not deleterious to metabolism and development as a whole and that convective oxygen transport via Hb is not essential for normal cardiovascular or respiratory function during larval development.

scholarly journals Developmental changes in oxygen consumption regulation in larvae of the South African clawed frog Xenopus laevis

1995 ◽  
Vol 198 (12) ◽  
pp. 2465-2475 ◽  
Author(s):  
D Hastings ◽  
W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Lactic Acid ◽  
Xenopus Laevis ◽  
South African ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Aerobic Metabolism ◽  
Whole Body ◽  
Lactate Levels ◽  
Clawed Frog

Well-developed larval Xenopus laevis (NF stages 58­66) are oxygen regulators, at least during mild hypoxia. When and how they change from oxygen conformers (the presumed condition of the fertilized egg) to oxygen regulators is unknown. Also unknown is how anaerobic metabolic capabilities change during development, especially in response to acute hypoxia, and to what extent, if any, anaerobiosis is used to supplement aerobic metabolism. Consequently, we have investigated resting rates of oxygen consumption (M.O2) and concentrations of whole-body lactate (lactic acid) during development in normoxia and in response to acute hypoxia in Xenopus laevis. M.O2 increased in an episodic, non-linear fashion during development. Resting, normoxic M.O2 increased about tenfold (to approximately 0.20 µmol g-1 h-1) between NF stages 1­39 and 40­44, and then another tenfold between NF stages 45­48 and 49­51 (to approximately 2.0 µmol g-1 h-1), remaining at about 2 µmol g-1 h-1 for the remainder of larval development. M.O2 reached its highest level in newly metamorphosed frogs (nearly 4 µmol g-1 h-1), before decreasing to about 1.0 µmol g-1 h-1 in large adults. X. laevis embryos and larvae up to NF stage 54­57 were oxygen conformers when exposed to variable levels of acute hypoxia. The only exception was NF stage 45­48 (external gills present yet body mass still very small), which showed some capability of oxygen regulation. All larvae older than stage 54­57 and adults were oxygen regulators and had the lowest values of Pcrit (the oxygen partial pressure at which M.O2 begins to decline). Whole-body lactate concentration in normoxia was about 1 µmol g-1 for all larval groups, rising to about 12 µmol g-1 in adults. Concentrations of lactic acid in NF stages 1­51 were unaffected by even severe ambient hypoxia. However, whole-body lactate levels in NF stages 52­66 increased in response to severe hypoxia, indicating that some anaerobic metabolism was being used to supplement diminishing aerobic metabolism. The largest increases in concentration of lactate occurred in late larvae and adults.

The Respiratory Physiology of the Marine Nematodes Enoplus Brevis (Bastian) and E. Communis (Bastian)

1973 ◽  
Vol 59 (1) ◽  
pp. 267-274
Author(s):  
H. J. ATKINSON
Keyword(s):  
Oxygen Consumption ◽  
Sea Water ◽  
Atmospheric Oxygen ◽  
Respiratory Physiology ◽  
Marine Nematodes ◽  
Oxygen Regime ◽  
Lower Oxygen ◽  
Rate Of Oxygen Consumption ◽  
Oxygen Tensions ◽  
Oxygen Requirements

1. The rate of oxygen consumption of individual male Enoplus brevis and E. communis was measured at 15 °C, after altering the oxygen regime experienced since the animals were collected. 2. When both E. brevis and E. communis were transferred to 35 Torr from atmospheric oxygen tensions, their oxygen consumption was only two-thirds of that of individuals maintained at this lower oxygen tension. 3. The rate of oxygen consumption of the two species at 135 Torr was unaltered by exposure for 2 h to oxygen-free sea water. 4. The results are discussed in relation to the overall influence of fluctuating oxygen regimes on the oxygen requirements of nematodes.

The Respiratory Physiology of the Marine Nematodes Enoplus Brevis (Bastian) and E. Communis (Bastian)

1973 ◽  
Vol 59 (1) ◽  
pp. 255-266
Author(s):  
H. J. ATKINSON
Keyword(s):  
Oxygen Consumption ◽  
Body Size ◽  
Oxygen Tension ◽  
Dry Weight ◽  
Respiratory Physiology ◽  
Rate Of Oxygen Consumption ◽  
Oxygen Tensions ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

1. The rate of oxygen consumption of individual males of Enoplus brevis and E. communis was measured at 15 °C and at each of four oxygen tensions, 135, 75, 35, and 12 Torr, after at least 12 h experience of these conditions. 2. It was clearly demonstrated that the level of oxygen consumption of both species was reduced by each lowering of the imposed oxygen tension. 3. In all cases the oxygen consumption of each species fell with increasing body size. On a unit dry-weight basis the oxygen consumption of E. brevis is greater than that of the larger E. communis, but after allowing for the difference of body size the two species have more or less similar oxygen uptakes at all oxygen tensions. 4. In E. brevis oxygen tension influenced the relationship of body size and metabolism, the slope relating oxygen consumption and body weight becomes steeper with decreasing oxygen tension. This effect was not shown by E. communis. 5. Some general factors influencing the availability of oxygen to nematodes are considered.

Effect of anaesthesia on insulin-induced hypoglycemia in rabbits

1988 ◽  
Vol 66 (12) ◽  
pp. 1531-1537 ◽  
Author(s):  
Fred J. Haynes ◽  
Surinder Cheema-Dhadli ◽  
Ross M. Halperin ◽  
Randy Zettle ◽  
Lisa Robinson ◽  
...  
Keyword(s):  
Energy Source ◽  
Oxygen Consumption ◽  
Glucose Oxidation ◽  
Lactate Concentration ◽  
Hepatic Glycogen ◽  
Rapid Rate ◽  
Energy Turnover ◽  
Rate Of Oxygen Consumption ◽  
Principal Energy ◽  
Insulin Overdose

The aim of this study was to determine how anaesthetized rabbits survive much longer than awake rabbits after receiving an insulin overdose. Insulin appeared to act in both groups of rabbits because there was a prompt fall in circulating glucose, free fatty acids, and β-hydroxybutyrate concentrations. Carbohydrate appeared to be the principal energy source for anaesthetized rabbits because their respiratory quotient approached unity. Although the fall in glycemia was similar in both groups of rabbits, the circulating lactate concentration rose only in the anaesthetized group. This rise in lactate in the initial 60 min after insulin was given could account for most of the fall in glycemia if the source of lactate was the glucose pool. The decline in hepatic glycogen was close to 100 μmol/g liver; this would account for about one-third of the total energy turnover and close to one-half of the measured glucose appearance in these anaesthetized rabbits. As judged from the rate of oxygen consumption, muscle glycogen seemed to supply two-thirds of the fuel to be oxidized in these rabbits. However, only one-third of the lactate released from muscle was first converted to glucose and the remainder was oxidized directly to CO2. Although insulin provided the metabolic setting for a rapid rate of glucose oxidation, this rate appeared to be diminished when the overall rate of oxygen consumption was lower during anaesthesia.

scholarly journals Functional conflicts between feeding and gas exchange in suspension-feeding tadpoles, Xenopus laevis

1984 ◽  
Vol 110 (1) ◽  
pp. 91-98 ◽  
Author(s):  
M. E. Feder ◽  
D. B. Seale ◽  
M. E. Boraas ◽  
R. J. Wassersug ◽  
A. G. Gibbs
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Xenopus Laevis ◽  
Suspension Feeding ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Metabolic Requirement ◽  
Rate Of Oxygen Consumption ◽  
Food Particles ◽  
Hypoxic Water

Air-breathing tadpoles of Xenopus laevis (Amphibia: Anura) use buccopharyngeal surfaces for both gas exchange and capture of food particles in the water. In dense food suspensions, tadpoles decrease ventilation of the buccopharynx and increase air breathing. The lung ventilatory frequency is elevated even though the rate of oxygen consumption is at or below resting levels, suggesting that the lung hyperventilation reflects compensation for decreased buccopharyngeal respiration rather than an increased metabolic requirement. If tadpoles in hypoxic water are prevented from breathing air, they increase buccopharyngeal respiration at the expense of feeding. Aerial respiration evidently permits the buccopharyngeal surfaces to be used primarily for food entrapment.

scholarly journals Aerial Versus Aquatic Oxygen Consumption in Larvae of the Clawed Frog, Xenopus Laevis

1984 ◽  
Vol 108 (1) ◽  
pp. 231-245 ◽  
Author(s):  
MARTIN E. FEDER ◽  
RICHARD J. WASSERSUG
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Xenopus Laevis ◽  
Total Oxygen ◽  
Pumping Rate ◽  
Aerial Respiration ◽  
Aquatic Respiration ◽  
Normal Feeding ◽  
Hypoxic Water ◽  
Clawed Frog

Tadpoles of Xenopus laevis Daudin can extract oxygen from both air and water. When these larvae have access to air, aerial oxygen uptake averages 16.6% of total oxygen consumption in normoxic water, and increases to 100% of net oxygen consumption in hypoxic water. Neither anaerobiosis nor increased buccopharyngeal ventilation occur in response to hypoxia. If tadpoles are prevented from surfacing to breathe air, they can maintain normal oxygen consumption through aquatic respiration alone in normoxic water, but not in hypoxic water. Unlike air-breathing larvae, exclusively water-breathing larvae respond to aquatic hypoxia by increasing their buccal pumping rate and by accumulating lactate. Even though Xenopus larvae can survive without air for many days, aerial respiration is necessary for other functions: tolerance of hypoxia, normal feeding, locomotion and buoyancy regulation.

Thyroid hormones and behavioral thermoregulation by Xenopus laevis: differential effects of thyroxine and triiodothyronine

1986 ◽  
Vol 64 (5) ◽  
pp. 1076-1079 ◽  
Author(s):  
R. Keith Dupré ◽  
John J. Just ◽  
J. P. Ritchart
Keyword(s):  
Oxygen Consumption ◽  
Xenopus Laevis ◽  
Thyroid Hormones ◽  
Hormone Treatment ◽  
Behavioral Thermoregulation ◽  
Temperature Selection ◽  
African Clawed Frog ◽  
Secondary Result ◽  
Clawed Frog ◽  
Selection Of

The effects of 1 μM 2,4-dinitrophenol, 2.5 × 10−8 M thyroxine, and 2.5 × 10−8 M triiodothyronine on the oxygen consumption and behavioral temperature selection of the African clawed frog, Xenopus laevis, were examined to test the hypothesis that the selection of lower temperatures by thyroxine-treated ectotherms is a secondary result of the calorigenic effect of the hormone. Treatment with the metabolic poison 2, 4-dinitrophenol produced a significant increase in oxygen consumption but had no significant influence on temperature selection by the clawed frogs, suggesting that an increase in oxygen consumption in itself does not induce the selection of lower temperatures by ectotherms. Furthermore, neither thyroxine nor triiodothyronine affected the standard oxygen consumption of the clawed frogs at 23 °C but both significantly affected behavioral temperature selection. Treatment with thyroxine resulted in the selection of significantly lower temperatures than untreated controls. Conversely, treatment with triiodothyronine resulted in the selection of significantly warmer temperatures. These data suggest that thyroid hormones do not affect behavioral thermoregulation of ectotherms via an indirect calorigenic effect but may act directly on the neural regions involved with the sensation and (or) integration of thermal information. These data further suggest independent roles for thyroxine and triiodothyronine in the modulation of temperature selection by anuran amphibians.

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

scholarly journals Association between Oxygen Consumption and Surface Electromyographic Amplitude and Its Variation within Individual Calf Muscles during Walking at Various Speeds

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1748
Author(s):  
Kohei Watanabe ◽  
Shideh Narouei
Keyword(s):  
Oxygen Consumption ◽  
Spatial Variation ◽  
Metabolic Response ◽  
Correlation Coefficients ◽  
Surface Emg ◽  
Medial Gastrocnemius ◽  
Whole Body ◽  
Young Males ◽  
Emg Amplitude ◽  
Calf Muscles

Surface electromyography (EMG) has been used to estimate muscle work and physiological burden of the whole body during human movements. However, there are spatial variations in surface EMG responses within individual muscles. The aim of this study was to investigate the relation between oxygen consumption and surface EMG responses of lower leg muscles during walking at various speeds and to quantify its spatial variation within an individual muscle. Nine young males walked on a treadmill at four speeds: preferred minus 1 km/h, preferred, preferred plus 1 km/h, and preferred plus 2 km/h, and the metabolic response was measured based on the expired gas. High-density surface EMG of the tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius, and soleus muscles was performed using 64 two-dimensional electrode grids. Correlation coefficients between oxygen consumption and the surface EMG amplitude were calculated across the gait speeds for each channel in the electrode grid and for individual muscles. Mean correlation coefficients across electrodes were 0.69–0.87 for the four individual muscles, and the spatial variation of correlation between the surface EMG amplitude and oxygen consumption within an electrode grid was significantly greater in MG muscle than in TA muscle (Quartile deviations: 0.24 for MG and 0.02 for TA, p < 0.05). These results suggest that the physiological burden of the whole body during gait at various speeds can be estimated from the surface EMG amplitude of calf muscles, but we need to note its spatial distribution within the MG muscle.

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