Metabolic control of Argyropelecus hemigymnus photophores: effects of glucose and pyruvate

1991 ◽  
Vol 69 (9) ◽  
pp. 2410-2413 ◽  
Author(s):  
J. Mallefet ◽  
F. Baguet
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Metabolic Control ◽  
Time Course ◽  
Light Emission ◽  
Mesopelagic Fish ◽  
Fresh Weight ◽  
Hypometabolic State ◽  
The Mean ◽  
Mean Time

Modifications in oxygen consumption and luminescence of isolated luminescent organs of the mesopelagic fish Argyropelecus hemigymnus following glucose and pyruvate administration were studied before and during light emission triggered by adrenaline. Isolated photophores (mean fresh weight 13.5 ± 0.9 mg) at rest, i.e., in the absence of light emission, in saline (20 °C) exhibit a respiration rate of 1.045 ± 0.082 (SE) nmol O2/min (n = 35). A significant decrease (p = 0.05) in oxygen consumption was observed after the addition of 5.5 mM glucose. Instead of the oxygen decrease usually observed as a result of control stimulations using adrenaline, photophores pretreated with glucose increased their oxygen uptake in response to adrenaline, and maximal light emission was reduced by 85% (p = 0.01). The addition of 5.5 mM pyruvate induced a significant transient increase (p = 0.05) in oxygen uptake of isolated photophores, though this treatment did not statistically modify the mean time course of oxygen consumption and light emission in response to adrenaline. The hypothesis of a hypometabolic state of the isolated photophores of A. hemigymnus during light emission is discussed.

Acetate as a metabolic substrate in the fetal lamb

1976 ◽  
Vol 230 (2) ◽  
pp. 357-361 ◽  
Author(s):  
VC Char ◽  
RK Creasy
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Maternal Blood ◽  
Mean Value ◽  
Fetal Blood ◽  
Blood Samples ◽  
Metabolic Substrate ◽  
Acetate Concentration ◽  
Fetal Lamb ◽  
The Mean

Fetal acetate metabolsim was studied in chronically catheterized fetal lambs of 110-141 days' gestation. Acetate concentration was measured enzymatically in whole blood drawn simultaneously from maternal and fetal pre- and postplacental vessels. The oxygen content of the fetal blood samples was also measured. Fetal umbilical venous acetate concentration was found to be proportional to the maternal arterial acetate concentration and had a mean value of 0.366 mM. Fetal blood acetate increased significantly, by a mean of 0.081 mM, during circulation through the placenta. This increase was proportional to both the maternal acetate concentration and the concentration gradient of acetate across the placenta. The mean maternal arterial acetate concentration was 1.153 mM. Maternal blood lost significant amounts of acetate, 0.112 mM, during circulation through the uterus and appeared to be the source of the acetate being gained by the fetus. It is estimated that a total of 23 mmol of acetate/kg of fetal weight is being taken up by the fetus each day, providing it with 0.560 g of carbon/kg. Comparisons of acetate uptake with fetal oxygen uptake indicate 10% of the daily fetal oxygen consumption would be required to completely oxidize the acetate being gained by the fetus.

scholarly journals The time course of adaptations in thermoneutral maximal oxygen consumption following heat acclimation

2019 ◽  
Vol 119 (10) ◽  
pp. 2391-2399 ◽  
Author(s):  
Mark Waldron ◽  
O. Jeffries ◽  
J. Tallent ◽  
S. Patterson ◽  
V. Nevola
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Time Course ◽  
Aerobic Power ◽  
Linear Time ◽  
Maximal Oxygen Consumption ◽  
Training Group ◽  
Heat Acclimation ◽  
Non Linear

Abstract Purpose This study investigated the effects of a 10-day heat acclimation (HA) programme on the time course of changes in thermoneutral maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max) during and up to 10 days post-HA. Methods Twenty-two male cyclists were assigned to a HA or control (Con) training group following baseline ramp tests of thermoneutral $$\dot{V}$$ V ˙ O2max. Ten days of fixed-intensity (50% baseline $$\dot{V}$$ V ˙ O2max) indoor cycling was performed in either ~ 38.0 °C (HA) or ~ 20 °C (Con). $$\dot{V}$$ V ˙ O2max was re-tested on HA days 5, 10 and post-HA days 1, 2, 3, 4, 5 and 10. Results $$\dot{V}$$ V ˙ O2max initially declined across time in both groups during training (P < 0.05), before increasing in the post-HA period in both groups (P < 0.05). However, $$\dot{V}$$ V ˙ O2max was higher than control by post-HA day 4 in the HA group (P = 0.046). Conclusions The non-linear time course of $$\dot{V}$$ V ˙ O2max adaptation suggests that post-testing should be performed 96-h post-training to identify the maximal change for most individuals. In preparation for training or testing, athletes can augment their aerobic power in thermoneutral environments by performing 10 days HA, but the full effects will manifest at varying stages of the post-HA period.

Unique Pattern of Pulmonary Function after Exercise in Patients with Cystic Fibrosis

1994 ◽  
Vol 6 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Ted. A. Kaplan ◽  
Gina Moccia ◽  
Robert M. McKey
Keyword(s):  
Cystic Fibrosis ◽  
Pulmonary Function ◽  
Time Course ◽  
Forced Expiratory Volume ◽  
Distinct Pattern ◽  
Degree Pattern ◽  
Function Test ◽  
The Mean ◽  
Exercise Induced ◽  
Mean Time

The purpose of this study was to assess the incidence, degree, pattern, and time course of pulmonary function test (PFT) changes measured after a dynamic exercise challenge. Forced expiratory maneuvers were performed before and serially after a 7-min run-walk in 44 patients with cystic fibrosis (CF). Twenty-four patients met at least one PFT criterion for exercise-induced bronchospasm (EIB) within 21 min after exercise, and 38 patients had >5% increase in a PFT parameter at some point after exercise. The mean time of greatest increase in PFTs occurred sooner than the greatest decrease, which was later than for 22 patients with asthma or allergic rhinitis found to have EIB. Age was inversely related to percentage fall in forced expiratory volume in 1 s (FEV,) after exercise. These results demonstrate a distinct pattern of PFTs measured after exercise in most patients with CF, with an early bronchodilation followed by a significant decrease in PFTs.

scholarly journals Comparison between Different Prescription Methods for Aerobic Training in Young Adults

2019 ◽  
Vol 11 (22) ◽  
pp. 6420
Author(s):  
Fernando Policarpo ◽  
Pedro Valdivia-Moral ◽  
Maria do Socorro Luna-Cruz ◽  
Alex Véliz-Burgos ◽  
Juan Mansilla-Sepulveda ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Aerobic Training ◽  
Direct Method ◽  
Reference Value ◽  
Fat Percentage ◽  
Mean Values ◽  
The Mean

Anaerobic threshold and respiratory compensation are used to determine the intensity of aerobic exercise. This study aims to compare heart rate values relative to the percentages of 50%, 60%, 70%, and 80%, a comparison calculated through the reserve heart rate (HRR) and reserve oxygen consumption (VO2R) equations corresponding to the oxygen consumption obtained by the direct method. The sample was composed of 11 men and 10 women: mean age, 21.4 ± 2.8 years. Volunteers performed a maximal treadmill test in which oxygen uptake was measured using the VO2000® metabolic analyzer. The mean body fat percentage was 15.68 ± 8.02% corresponding to a lean body mass of 54.8 ± 13.0 kg and a maximal oxygen uptake (VO2max) of 56.0 ± 8.4 mL/Kg·min−1. The measured intensities (50%, 60%, 70% and 80% of VO2max) presented significant differences (p < 0.05) for each reference value. Mean values calculated by the HRR equation demonstrated a tendency to underestimate the intensities, while the values calculated by the VO2R equation showed a tendency to overestimate the intensities. As the main conclusion, it is pointed out that both methods were effective for determining the intensity of aerobic training. However, they presented significant differences, and the equations should be adjusted to increase precision. Thus, the use of HRR is recommended for the determination of training intensities.

Comparative Effects of Ethacrynic Acid, Furosemide, and Diazoxide in the Perfused Dog Hindlimb

1971 ◽  
Vol 49 (12) ◽  
pp. 1038-1043 ◽  
Author(s):  
R. I. Ogilvie ◽  
E. Schlieper
Keyword(s):  
Dose Response ◽  
Time Course ◽  
Ethacrynic Acid ◽  
Maximal Effect ◽  
Vasodilator Effect ◽  
Arterial Blood ◽  
The Mean ◽  
Mean Time ◽  
Higher Doses ◽  
Vasodilating Effect

The vasodilator effects of intravenous ethacrynic acid (EA), furosemide (F), and diazoxide (DZ) were compared in the hindlimb of anesthetized anephric dogs, perfused with a constant inflow of arterial blood. A dose-response relationship was demonstrated for all three agents. The curves for EA and F were parallel and relatively flat, with EA being 10 times more potent than F in producing vasodilatation of the perfused limb. The dose–response for DZ was steep and the maximal vasodilator response observed at the lowest dose of DZ (5 mg/kg) did not differ from that at the highest doses of EA (10 mg/kg) or F (100 mg/kg). The maximal vasodilator effect of DZ in the perfused hindlimb occurred within 2 min after intravenous administration. After the higher doses of F there was a transitory vasodilator effect within 2 min but the maximal and more persistent effect was not observed until much later. The mean time for maximal effect was 40 min for EA, 46 min for F, and 2 min for DZ. The time course of vasodilator effect and maximal observed effect for EA and F was not altered by intraarterial administration nor by sympathetic decentralization of the perfused hindlimb. We conclude that F, like EA, has a direct vasodilating effect on peripheral arterioles and both EA and F probably act by a different mechanism than DZ.

scholarly journals PHENOTYPIC EXPRESSION OF A GENETIC PROPERTY INTRODUCED BY DEOXYRIBONUCLEATE

1959 ◽  
Vol 42 (4) ◽  
pp. 737-748 ◽  
Author(s):  
Maurice S. Fox
Keyword(s):  
Standard Deviation ◽  
Time Course ◽  
Distribution Curve ◽  
Phenotypic Expression ◽  
Normal Distribution Curve ◽  
Phenotypic Alteration ◽  
The Mean ◽  
Definition Of ◽  
Two Parameters ◽  
Mean Time

The time course of the appearance of cells showing a new phenotype, following treatment with a specific DNA, has been analyzed. A plot as a function of time of the number of cells showing the new property closely resembles the summation under a normal distribution curve. Describing the appearance of the new phenotype in these terms permits the definition of two parameters, the mean time, and the standard deviation of the distribution curve. This distribution is not affected either by the DNA concentration with which the transformable population has been treated, or by the streptomycin concentration with which the transformed population has been challenged. Interruptions of the expression process, by cooling to 20° or 0°C., serve only to displace the expression curves, without changing their shape, while small reductions in temperature change both the mean time of expression and the standard deviation of the distribution curve. On the basis of these observations a number of hypotheses have been examined concerning the mechanism whereby transforming DNA manifests a phenotypic alteration in the transformed cells. It can be concluded that there exist at least two stages in the process of expression. The completion of the first stage, causing the randomization, occurs with a mean time of about 60 minutes, and a terminal step, that of the transition of phenotype, occurs in less than 3 minutes.

Time course of aerobic recovery after contraction of rabbit papillary muscle

1987 ◽  
Vol 253 (2) ◽  
pp. H325-H332 ◽  
Author(s):  
F. Mast ◽  
G. Elzinga
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Time Constant ◽  
Oxygen Consumption Rate ◽  
Time Course ◽  
Consumption Rate ◽  
Oxygen Storage ◽  
Measuring System ◽  
Measured Time ◽  
Isometric Twitch

The time course of oxygen uptake after isometric twitch contractions of isolated rabbit papillary muscles was determined at 20 degrees C by continuous polarographic measurement of the partial pressure of oxygen in a 219-microliters glass chamber in which the fluid circulated rapidly. The response time of the oxygen-measuring system was characterized by a delay of 1.1 s and a time constant of 2.1 s after that delay. Depending on the stimulation frequency (0.125–1.0 Hz) the total amount of oxygen uptake for 120 twitches varied from 5.3 to 32.7 nmol/mg dry wt, and the steady-state oxygen consumption rate varied from 0.4 to 8.5 nmol X min-1 X mg dry wt-1. On the basis of a diffusion model we eliminated the effect of oxygen storage on the measured time course of oxygen consumption to determine the mitochondrial kinetics. We found a time constant of an average 19–22 s of mitochondrial off kinetics. By use of this time constant for the change in oxygen consumption rate after contraction, it can be estimated that 9–10% of the oxygen required to restore ATP levels is already taken up by the mitochondria during the twitch.

scholarly journals METABOLIC CONTROL OF LUMINESCENCE IN ISOLATED PHOTOPHORES OF PORICHTHYS: EFFECTS OF GLUCOSE ON OXYGEN CONSUMPTION AND LUMINESCENCE

1993 ◽  
Vol 181 (1) ◽  
pp. 279-293
Author(s):  
J. Mallefet ◽  
F. Baguet
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Light Emission ◽  
Potassium Cyanide ◽  
Cellular Respiration ◽  
Slow Phase ◽  
Light Reaction ◽  
Fast Phase ◽  
Light Production ◽  
Rate Of Oxygen Consumption

1. Basal oxygen consumption of isolated photophores from Porichthys sp. at rest, i.e. without light emission, increased significantly from 0.101+/− 0.021 nmol min-1 to 0.173+/−0.016 nmol min-1 in response to the addition of 5.5 mmol l-1 glucose. 2. 5.5 mmol l-1 glucose pretreatment modified the time course of the two phases of adrenaline-induced luminescence; an increase in oxygen consumption was observed during the fast phase of light production but a decrease occurred during the slow phase of luminescence. 3. Pretreatment of isolated photophores with 5.5 mmol l-1 glucose totally inhibited the light emission induced by 1 mmol l-1 potassium cyanide. With this treatment, the respiration rate decreased progressively and after 40 min reached a value not significantly different from zero. 4. Even after blockage of cellular respiration by cyanide, an increase in the rate of oxygen consumption was observed during the fast adrenaline- induced luminescence. 5. Glucose utilisation by glycolysis or by oxidative metabolism may provide energy to an inhibitory mechanism that maintains the photophores in a non- luminescent state. 6. We suggest that the oxygen consumed during the fast phase of adrenaline luminescence could represent the activity of an extramitochondrial oxidative pathway involved in the light reaction.

Relative contributions of passive equilibrium and active transport to the distribution of chloride in mammalian cortical neurons

1988 ◽  
Vol 60 (1) ◽  
pp. 105-124 ◽  
Author(s):  
S. M. Thompson ◽  
R. A. Deisz ◽  
D. A. Prince
Keyword(s):  
Time Constant ◽  
Cortical Neurons ◽  
Time Course ◽  
Chloride Concentration ◽  
Reversal Potential ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Gamma Aminobutyric Acid ◽  
The Mean ◽  
Mean Time

1. Active and passive factors affecting the chloride gradient of cortical neurons were assessed using intracellular recordings from neurons in slices of cingulate cortex maintained in vitro. The chloride equilibrium potential (ECl-) was estimated indirectly from the reversal potentials of responses to perisomatic gamma-aminobutyric acid (GABA) application and the Cl(-)-dependent inhibitory postsynaptic potential (IPSP). Under control conditions the mean resting potential (Vm; -69.7 mV) was not significantly different than the mean IPSP reversal potential (EIPSP; -70.1 mV). 2. Increasing the external potassium concentration ([K+]o) from 1 to 10 mM shifted the mean EIPSP from -80.4 to -61.8 mV. The mean EIPSP was approximately equal to the mean Vm at all [K+]oS. The conditions of Donnan equilibrium are not met in [K+]o less than 10 mM. 3. Polarization of Vm up to 20 mV away from EIPSP for 4 min with maintained current injection had no significant effect on EIPSP. 4. The GABA reversal potential was maintained 37-52 mV less negative than Vm after equilibration in saline in which the external chloride concentration had been reduced from 133 to 5 mM by substitution with isethionate. Vm and input resistance were not significantly different from control values in cells recorded under these conditions. 5. We conclude that Cl- is not passively distributed in cortical neurons, perhaps due to a low resting Cl- permeability. 6. Impalement with electrodes containing 2 M KCl resulted in a rapid 10 mV depolarizing shift in EIPSP that then remained relatively constant. Intracellular iontophoresis of Cl- resulted in a further depolarizing shift of EIPSP of 5-10 mV that returned to control in less than 1 min. The time course of recovery of IPSP amplitude could be fit with a single exponential having a mean time constant of 6.9 +/- 1.5 s and was independent of the amount of Cl- injected or stimulation frequency. 7. Reductions in temperature from 37 to 32 degrees C significantly increased the mean time constant of IPSP recovery from Cl- injection to 11.1 +/- 3.3 s, corresponding to Q10 = 2.6.(ABSTRACT TRUNCATED AT 400 WORDS)

Predicting Daily Maintenance Dose of Fluindione, an Oral Anticoagulant Drug

1996 ◽  
Vol 75 (05) ◽  
pp. 731-733 ◽  
Author(s):  
V Cazaux ◽  
B Gauthier ◽  
A Elias ◽  
D Lefebvre ◽  
J Tredez ◽  
...  
Keyword(s):  
Effective Dose ◽  
Maintenance Dose ◽  
Successive Approximations ◽  
Hemorrhagic Complication ◽  
Simple Method ◽  
Individual Variations ◽  
Anticoagulant Drug ◽  
The Mean ◽  
Mean Time ◽  
Daily Maintenance Dose

SummaryDue to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.

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