Augmented respiration in a flying insect

1998 ◽  
Vol 201 (16) ◽  
pp. 2359-2366 ◽  
Author(s):  
Y Komai
Keyword(s):  
Gas Exchange ◽  
Stroke Volume ◽  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Sweet Potato ◽  
Longitudinal Muscle ◽  
Tethered Flight ◽  
Positional Angle ◽  
The Mean

The properties of the gas transport system in a tethered flying insect were investigated by directly measuring the oxygen partial pressure (PO2) in a wing muscle of the sweet potato hawkmoth Agrius convolvuli using a needle electrode. At rest, a distribution of PO2 corresponding to levels in the muscle and tracheal structures was observed. At the onset of tethered flight, PO2 in the muscle decreased. However, during a long stable flight, PO2 increased and reached a plateau approximately 2 min after the onset of flight. During stable tethered flight, PO2 in the centre of the second layer of the dorsal longitudinal muscle was locally higher than that during rest. As wing amplitude increased, PO2 increased in spite of the concurrent increase in metabolic rate. During tethered flight at a constant wing amplitude, PO2 was proportional to the mean wing positional angle. The results suggest that this insect effectively uses muscle movement, which increases the frequency and stroke volume of ventilation, to augment gas exchange during flight.

Preliminary evaluation of a predictive controller for a rotary blood pump based on pulmonary oxygen gas exchange

2019 ◽  
Vol 233 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Feng Huang ◽  
Zhe Gou ◽  
Yang Fu
Keyword(s):  
Gas Exchange ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Left Ventricular ◽  
Blood Pump ◽  
Rotary Blood Pump ◽  
Blood Pumps ◽  
Control Objective ◽  
Predictive Controller ◽  
Rotary Blood Pumps

Physiological control of rotary blood pumps is becoming increasingly necessary for clinical use. In this study, the mean oxygen partial pressure in the upper airway was first quantitatively evaluated as a control objective for a rotary blood pump. A model-free predictive controller was designed based on this control objective. Then, the quantitative evaluation of the controller was implemented with a rotary blood pump model on a complete cardiovascular model incorporated with airway mechanics and gas exchange models. The results show that the controller maintained a mean oxygen partial pressure at a normal and constant level of 138 mmHg in the left heart failure condition and restored basic haemodynamics of blood circulation. A left ventricular contractility recovery condition was also replicated to assess the response of the controller, and a stable result was obtained. This study indicates the potential use of the oxygen partial pressure index during pulmonary gas exchange when developing a multi-objective physiological controller for rotary blood pumps.

Effect of varying alveolar oxygen partial pressure on diffusing capacity for nitric oxide and carbon monoxide, membrane diffusing capacity and lung capillary blood volume

1991 ◽  
Vol 81 (6) ◽  
pp. 759-765 ◽  
Author(s):  
C. D. R. Borland ◽  
Y. Cox
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Novel Method ◽  
The Mean ◽  
Alveolar Oxygen

1. To examine the effect of varying oxygen partial pressure (Pao2) on nitric oxide (DLNO) and carbon monoxide (DLCO) diffusing capacity (transfer factor), 10 subjects performed combined DLCO/DLNO measurements with the inspired mixture made up with three different oxygen concentrations (25%, 18% and 15%) to give Pao2 values of 12–20 kPa. 2. A novel method is described for calculating membrane diffusing capacity (DM) and pulmonary capillary volume (Qc) from DLNO and DLCO. 3. The mean DMCO was 52.89 mmol min−1 kPa−1 and Qc was 0.056 litre. Reducing Pao2 from 20 to 12 kPa resulted in an increase in DLCO = −0.124 (O2%) + 11.67 (P < 0.001) and a fall in DLNO = 0.538 (O2%) + 32.01 (P < 0.001) and a fall in DLNO/DLCO = 0.107 (O2%) + 2.52 (P < 0.001). DM (P = 0.59) and Qc (P = 0.64) also tended to fall with falling Pao2. 4. It appears more likely that the minor reduction in DLNO that we have observed with falling Pao2 is due to diffusion rather than reaction limitation.

scholarly journals Oxygen supply capacity breathes new life into critical oxygen partial pressure (Pcrit)

2021 ◽  
Vol 224 (8) ◽  
Author(s):  
Brad A. Seibel ◽  
Alyssa Andres ◽  
Matthew A. Birk ◽  
Alexandra L. Burns ◽  
C. Tracy Shaw ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Supply ◽  
Accurate Determination ◽  
Maximum Energy ◽  
Hypoxia Tolerance ◽  
Energy Demands ◽  
Critical Oxygen ◽  
Supply Capacity

ABSTRACT The critical oxygen partial pressure (Pcrit), typically defined as the PO2 below which an animal's metabolic rate (MR) is unsustainable, is widely interpreted as a measure of hypoxia tolerance. Here, Pcrit is defined as the PO2 at which physiological oxygen supply (α0) reaches its maximum capacity (α; µmol O2 g−1 h−1 kPa−1). α is a species- and temperature-specific constant describing the oxygen dependency of the maximum metabolic rate (MMR=PO2×α) or, equivalently, the MR dependence of Pcrit (Pcrit=MR/α). We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The MR need not be constant (regulated), standardized or exhibit a clear breakpoint at Pcrit for accurate determination of α. The α-method has several advantages over Pcrit determination and non-linear analyses, including: (1) less ambiguity and greater accuracy, (2) fewer constraints in respirometry methodology and analysis, and (3) greater predictive power and ecological and physiological insight. Across the species evaluated here, α values are correlated with MR, but not Pcrit. Rather than an index of hypoxia tolerance, Pcrit is a reflection of α, which evolves to support maximum energy demands and aerobic scope at the prevailing temperature and oxygen level.

scholarly journals Oxygen supply capacity in animals evolves to meet maximum demand at the current oxygen partial pressure regardless of size or temperature

2019 ◽  
Author(s):  
Brad A. Seibel ◽  
Curtis Deutsch
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Thermal Tolerance ◽  
Oxygen Supply ◽  
Cardiovascular Health ◽  
Hypoxia Tolerance ◽  
Aerobic Scope ◽  
Supply Capacity

AbstractPhysiological oxygen supply capacity is associated with athletic performance and cardiovascular health and is thought to cause hypometabolic scaling in diverse species. Environmental oxygen is widely believed to be limiting of metabolic rate and aerobic scope, setting thermal tolerance and body size limits with implications for species diversity and biogeography. Here we derive a quantifiable linkage between maximum and basal metabolic rate and their temperature, size and oxygen dependencies. We show that, regardless of size or temperature, the capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure which, for most species assessed, is the current atmospheric pressure. Any reduction in oxygen partial pressure from current values will result in a decrement in maximum metabolic performance. However, oxygen supply capacity does not constrain thermal tolerance and does not cause hypometabolic scaling. The critical oxygen pressure, typically viewed as an indicator of hypoxia tolerance, instead reflects adaptations for aerobic scope. This simple new relationship redefines many important physiological concepts and alters their ecological interpretation.One sentence summary: Metabolism is not oxygen limited

scholarly journals Flight metabolic rate ofLocusta migratoriain relation to oxygen partial pressure in atmospheres of varying diffusivity and density

2017 ◽  
Vol 220 (23) ◽  
pp. 4432-4439 ◽  
Author(s):  
Edward P. Snelling ◽  
Rebecca Duncker ◽  
Karl K. Jones ◽  
Erinn P. Fagan-Jeffries ◽  
Roger S. Seymour
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure

scholarly journals Breathing new life into the critical oxygen partial pressure (Pcrit): a new definition, interpretation and method of determination

2020 ◽  
Author(s):  
B. A. Seibel ◽  
A. Andres ◽  
M. A. Birk ◽  
A. L. Burns ◽  
C. T. Shaw ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Supply ◽  
Break Point ◽  
Standard Metabolic Rate ◽  
Hypoxia Tolerance ◽  
Additional Species ◽  
Critical Oxygen ◽  
Mechanistic Basis

AbstractThe critical oxygen partial pressure (Pcrit) is most commonly defined as the oxygen partial pressure below which an animal’s standard metabolic rate can no longer be maintained. It is widely interpreted as measure of hypoxia tolerance, which influences a species’ aerobic scope and, thus, constrains biogeography. However, both the physiology underlying that interpretation and the methodology used to determine Pcrit remain topics of active debate. The debate remains unresolved in part because Pcrit, as defined above, is a purely descriptive metric that lacks a clear mechanistic basis. Here we redefine Pcrit as the PO2 at which physiological oxygen supply is maximized and refer to these values, thus determined, as Pcrit-α. The oxygen supply capacity (α) is a species- and temperature-specific coefficient that describes the slope of the relationship between the maximum achievable metabolic rate and PO2. This α is easily determined using respirometry and provides a precise and robust estimate of the minimum oxygen pressure required to sustain any metabolic rate. To determine α, it is not necessary for an individual animal to maintain a consistent metabolic rate throughout a trial (i.e. regulation) nor for the metabolic rate to show a clear break-point at low PO2. We show that Pcrit-α can be determined at any metabolic rate as long as the organisms’ oxygen supply machinery reaches its maximum capacity at some point during the trial. We reanalyze published representative Pcrit trials for 40 species across five phyla, as well as complete datasets from six additional species, five of which have not previously been published. Values determined using the Pcrit-α method are strongly correlated with Pcrit values reported in the literature. Advantages of Pcrit-α include: 1) Pcrit-α is directly measured without the need for complex statistics that hinder measurement and interpretation; 2) it makes clear that Pcrit is a measure of oxygen supply, which does not necessarily reflect hypoxia tolerance; 3) it alleviates many of the methodological constraints inherent in existing methods; 4) it provides a means of predicting the maximum metabolic rate achievable at any PO2, 5) Pcrit-α sheds light on the temperature- and size-dependence of oxygen supply and metabolic rate and 6) Pcrit-α can be determined with greater precision than traditional Pcrit.

scholarly journals Impact of the Method Used to Select Gas Exchange Data for Estimating the Resting Metabolic Rate, as Supplied by Breath-by-Breath Metabolic Carts

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 487
Author(s):  
Juan M.A. Alcantara ◽  
Guillermo Sanchez-Delgado ◽  
Francisco J. Amaro-Gahete ◽  
Jose E. Galgani ◽  
Jonatan R. Ruiz
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Time Interval ◽  
Metabolic Cart ◽  
Coefficients Of Variation ◽  
Human Energy ◽  
The Mean ◽  
Middle Aged Adults ◽  
Exchange Data

The method used to select representative gas exchange data from large datasets influences the resting metabolic rate (RMR) returned. This study determines which of three methods yields the lowest RMR (as recommended for use in human energy balance studies), and in which method the greatest variance in RMR is explained by classical determinants of this variable. A total of 107 young and 74 middle-aged adults underwent a 30 min RMR examination using a breath-by-breath metabolic cart. Three gas exchange data selection methods were used: (i) steady state (SSt) for 3, 4, 5, or 10 min, (ii) a pre-defined time interval (TI), i.e., 6–10, 11–15, 16–20, 21–25, 26–30, 6–25, or 6–30 min, and (iii) “filtering”, setting thresholds depending on the mean RMR value obtained. In both cohorts, the RMRs yielded by the SSt and filtering methods were significantly lower (p < 0.021) than those yielded by the TI method. No differences in RMR were seen under the different conditions of the SSt method, or of the filtering method. No differences were seen between the methods in terms of the variance in RMR explained by its classical determinants. In conclusion, the SSt and filtering methods return the lowest RMRs and intra-measurement coefficients of variation when using breath-by-breath metabolic carts.

Respiratory gases in uterine circulation of pregnant domestic swine as sampled by indwelling catheters

1978 ◽  
Vol 234 (1) ◽  
pp. R25-R28 ◽  
Author(s):  
D. Caton ◽  
F. W. Bazer
Keyword(s):  
Gas Exchange ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Significant Relationship ◽  
Venous Blood ◽  
Mean Value ◽  
Indwelling Catheters ◽  
Respiratory Gases ◽  
Uterine Circulation ◽  
Domestic Swine

Data dealing with placental respiratory gas exchange are scant for species with an epitheliochorial placenta. None have been obtained from awake, unstressed animals. For this reason 18 pregnant swine were prepared with chronically implanted polyvinyl catheters. Respiratory gases in arterial and uterine venous blood were observed between the 30th day of gestation and term (110 days). There was a statistically significant relationship between uterine venous oxygen partial pressure (Po2 and the day of gestation. The value for Po2, fell from a mean of 70 to 57 Torr. The latter appears to be the highest mean value yet observed in uterine vein of any species at term. pregnancy; chronic preparation Submitted on March 7, 1977

Energy metabolism of eucalyptus-boring beetles at rest and during locomotion: gender makes a difference

2000 ◽  
Vol 203 (7) ◽  
pp. 1131-1139 ◽  
Author(s):  
G.L. Rogowitz ◽  
M.A. Chappell
Keyword(s):  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Flight Activity ◽  
Activity Levels ◽  
Aerobic Scope ◽  
Tethered Flight ◽  
Seeking Behavior ◽  
Males And Females ◽  
The Mean ◽  
Phoracantha Recurva

We studied metabolic rates during rest, maximal running exercise and tethered flight in the long-horned eucalyptus-boring beetles Phoracantha recurva and P. semipunctata. Simultaneous measurement of rates of O(2) consumption (vdot (O2)) and CO(2) production (vdot (CO2)) indicated that vdot (CO2) closely approximated vdot (O2) and hence was a good index of aerobic metabolic rate. The resting metabolic rate (RMR), peak vdot (CO2) during running-wheel locomotion (MR(run)) and factorial scope during running (MR(run)/RMR) are similar to published values for several other insect taxa. MR(run) was repeatable for most test groups over intervals of 48–96 h. Studies of P. semipunctata show that MR(run) is relatively insensitive to changes in ambient temperature (T(a)) between 20 and 30 degrees C, whereas resting metabolic rate increases with T(a) with a normal Q(10) (2.4). Consequently, factorial scope declines at the higher T(a): mean factorial scopes for male and female P. semipunctata are 17.7 and 13.6 at 20 degrees C versus 8.9 and 5.5 at 30 degrees C, respectively. Flight activity requires a considerably greater metabolic rate than terrestrial activity: at T(a) values of 20–30 degrees C, the mean factorial scope for flight activity of male P. semipunctata is 72 (range 36–110). Nevertheless, our measurements of flight metabolic rate in Phoracantha spp. are considerably lower than predicted from allometric equations for other insects. Our most interesting finding was that males of both species had a substantially and significantly higher MR(run) and aerobic scope than females. The gender differences in MR(run) are consistent with differences in activity levels of males and females during mate-seeking behavior.

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