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1.
B. Grubb G. E. Folk Jr. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,128(2):185-188
Summary The rate of oxygen consumption (
) by skeletal muscle was investigated in isolated perfused hindlimbs of laboratory rats and lemmings (Lemmus). In both species,
increased in proportion to blood flow rate, even at flow rates 4–5 times above resting level. The slope of the line relating
to skeletal muscle blood flow was significantly greater in the lemming than in the rat. This may be related to the inverse relationship between body weight and metabolic rate. These data support the hypothesis that in small animals a dependent relationship exists between blood flow and skeletal muscle
. 相似文献
2.
Jack P. Hayes 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(4):453-459
Summary I compared the maximal aerobic metabolic rates (
), field metabolic rates (FMR), aerobic reserves (
-FMR), and basal metabolic rates (BMR) of wild and recently captured deer mice from low (440 m) and high (3800 m) altitudes. To separate the effects of the thermal environment from other altitudinal effects, I examined mice from different altitudes, but similar thermal environments (i.e., summer mice from high altitude and winter mice from low altitude). When the thermal environment was similar,
, FMR, and aerobic reserve of low and high altitude mice did not differ, but BMR was significantly higher at high altitude. Thus, in the absence of thermal differences, altitude had only minor effects on the aerobic metabolism of wild or recently captured deer mice.At low altitude, there was significant seasonal variation in
, FMR, and aerobic reserve, but not BMR. BMR was correlated with
, but not with FMR. The significant positive correlation of BMR with
indicates a cost of high
, because higher BMR increases food requirements and energy use during periods of thermoneutral conditions.Abbreviations
BMR
basal metabolic rate
-
FMR
field metabolic rate
-
partial pressure of oxygen
-
T
a
ambient temperature
-
T
b
body temperature
-
T
e
operative temperature
-
maximal aerobic metabolic rate 相似文献
3.
Barbara Grubb G. E. Folk 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1976,110(2):217-226
Summary The purpose of this study was to determine the effect of norepinephrine (NE) on oxygen consumption (
) of perfused (constant flow) muscle in cold acclimated (CA) and control rats. Infusion of NE for a five minute period caused an increase in
of similar magnitude in both groups. Infusion of NE for 30 min resulted in an elevated steady state
in the cold acclimated group, while the control group showed only an initial increase in
followed by a continual decline during the remainder of the 30 min infusion period. These results suggest that when rats are challenged by cold exposure, the magnitude of the initial muscle response to NE by control and acclimated rats is the same, but a useful sustained higher muscle oxygen consumption is found only in the cold acclimated animals.Abbreviations CA
cold acclimated
- NE
norepinephrine 相似文献
4.
D. L. Evans R. J. Rose 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):791-799
Summary Six Standardbred horses were used to evaluate the time course of pulmonary gas exchange, ventilation, heart rate (HR) and acid base balance during different intensities of constant-load treadmill exercise. Horses were exercised at approximately 50%, 75% and 100% maximum oxygen uptake (
max) for 5 min and measurements taken every 30 s throughout exercise. At all work rates, the minute ventilation, respiratory frequency and tidal volume reached steady state values by 60 s of exercise. At 100%
max, the oxygen consumption (
) increased to mean values of approximately 130 ml/kg·min, which represents a 40-fold increase above resting
. At the low and moderate work rates,
showed no significant change from 30 s to 300 s of exercise. At the high work rate, the mean
at 30 s was 80% of the value at 300 s. The HR showed no significant change over time at the moderate work rate but differing responses at the low and high work rates. At the low work rate, the mean HR decreased from 188 beats/min at 30 s to 172 beats/min at 300 s exercise, whereas at the high work rate the mean HR increased from 204 beats/min at 30 s to 221 beats/min at 300 s exercise. No changes in acid base status occurred during exercise at the low work rate. At the moderate work rate, a mild metabolic acidosis occurred which was nonprogressive with time, whereas the high work rate resulted in a progressive metabolic acidosis with a base deficit of 16 mmol/l by 300 s exercise. It is concluded that the kinetics of gas exchange during exercise are more rapid in the horse than in man, despite the relatively greater change in
in the horse when going from rest to high intensity exercise.Symbols and abbreviations E
minute ventilation
-
V
T
tidal volume
-
oxygen uptake
-
carbon dioxide output
-
oxygen pulse
-
ventilatory equivalent for oxygen
-
ventilatory equivalent for carbon dioxide
- R
respiratory exchange ratio
- HR
heart rate
- SBC
standard bicarbonate
- STPD
standard temperature and pressure dry
- BTPS
body temperature and pressure saturated
-
arterial oxygen content
-
arteriovenous oxygen content difference
- Rf
respiratory frequency 相似文献
5.
Stephen C. Wood Kjell Johansen Mogens L. Glass G. M. O. Maloiy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,127(4):331-336
Summary Oxygen consumption
was measured at rest and during spontaneous activity at body temperatures of 25 and 35°C in 14 fasting Savanna monitor lizards,Varanus exanthematicus ranging in weight from 172 to 7500 g. The allometric relationship between metabolic rate at 25°C and body weight (W) is given by:
(ml O2 STPD·g–1·hr–1)=0.88W
–0.43 (Fig. 2). Although statistical comparisons are equivocal, this intraspecific size dependence exceeds that reported for interspecific comparisons among reptiles and other vertebrate groups (Fig 3). A reproducible diurnal pattern of activity was observed in undisturbed animals with minimum values of
between 2400 and 0800 h (Fig. 1). Spontaneous activity and
generally reached peak values between 1200 and 2000 hrs. The average ratio of active aerobic metabolic rate (AMR) to minimum (standard) aerobic metabolic rate (SMR) was 8.2. This voluntary AMR/SMR inVaranus exceeds the AMR/SMR for most reptiles stimulated to exhaustion. The high aerobic capacity is consistent with other evidence for efficient exchange and transport of respiratory gases inV. exanthematicus; e.g., low or absent intracardiac shunt flow resulting in high arterial saturation and low ventilation
and perfusion
requirements. 相似文献
6.
Donald C. Jackson Henry D. Prange 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1979,134(4):315-319
Summary Ventilation and metabolic rate were measured during exercise in adult female green turtles at Tortuguero, Costa Rica. Six turtles were studied at night on the beach while actively covering their nests. Five turtles, captured after nesting, were studied at rest, during 20 min of spontaneous activity, and during recovery from the activity. Arterial blood samples were obtained from the latter animals and analyzed for pH,
, O2 concentration and lactate concentration. Blood was obtained by heart puncture from 8 turtles immediately after nesting and analyzed for blood lactate. Active metabolism (
) in both groups was almost 10 times the standard resting value (0.024 l/kg·h). The increase in ventilation during exercise, due exclusively to higher breathing frequency, exceeded the increase in
, so that the ratio
(the air convection requirement), more than doubled. The respiratory exchange ratio,
, that averaged 0.56 in the resting turtles, increased to 1.08 during exercise in the captured turtles and was 0.90 in the nesting animals. Arterial
and O2 saturation remained unchanged during exercise, indicating efficient gas exchange in the lungs. Pre-exercise values of all variables were restored 1 h after the end of exercise. Blood acid-base changes associated with activity in the captive turtles were variable and not statistically significant, but suggested partially compensated metabolic acidosis. Lactate concentrations were significantly elevated in the nesting turtles. 相似文献
7.
Gregory K. Snyder Wesley W. Weathers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1977,117(3):291-301
Summary Resting rates of O2 consumption
against
, exercise endurance times and
during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against
was also measured inS. occidentalis captured above 2850 m. When
was recorded continuously, as ambient
was slowly reduced from 155 Torr, it became directly dependent upon ambient
between 110 and 120 Torr. The critical
for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher
's when ambient
was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m (
130 Torr). Both the higher
under hypoxia and the greater endurance roughly parallel a significantly greater maximum
in the high altitude lizards. At a simulated altitude of 3600 m (
100 Torr), maximum
and rate of recovery of the O2 debt calculated from post active
were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of
endurance or the altitude at which the lizards were captured. 相似文献
8.
Tamir M. Ellis Mark A. Chappell 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(3):393-402
Summary Thermogenic incubation has been documented in two large species of pythons, but the phenomenon has not been studied in small species with concomitantly large heat transfer coefficients. We describe behavior, metabolic rates, mass changes, and temperature relations for adult ball pythons (Python regius), the smallest member of the genus, during the reproductive cycle. Egg and hatchling metabolism and hatchling growth rates were also examined.Rates of oxygen consumption (
) of both gravid and non-gravid snakes showed typical ectothermic responses to changing ambient temperature (T
a). TheQ
10 forT
a's of 20–35°C was 2.2–2.3. The
of gravid females was significantly greater than that of non-gravid snakes at allT
a. Maximum oxygen consumption (
max) during forced exercise was about 12 times resting
atT
a=30°C.Eggs (5–6 per female) were laid in April. Total clutch mass was approximately 32% of the females' pre-oviposition mass. After oviposition, mother snakes coiled tightly around their clutches and remained in close attendance until the eggs hatched in June. Sudden decreases inT
a elicited abrupt but transient 2- to 4-fold increases in the
of incubating females. Similar responses were not observed in non-incubating snakes. The steady-state
of incubating females was independent ofT
a. In no case was body temperature (T
b) elevated more than a few tenths of a degree aboveT
a in steady-state conditions.The
of developing eggs increased sigmoidally through the 58–70 day incubation period. Total oxygen consumption during incubation atT
a=29.2°C was about 3.61 per egg. Young snakes quadrupled their mass during their first year of growth.Compared to larger python species which are endothermic during incubation, ball pythons have similar aerobic scopes and higher mass-specific
max. However, effective endothermy in ball pythons is precluded by high thermal conductance and limited energy stores. 相似文献
9.
T. B. R. J. Smith W. G. Hopkins N. A. S. Taylor 《European journal of applied physiology and occupational physiology》1994,69(1):44-49
The position of the body and use of the respiratory muscles in the act of rowing may limit ventilation and thereby reduce maximal aerobic power relative to that achieved in cycling or running, in spite of the greater muscle mass involved in rowing. This hypothesis was investigated for three groups of male subjects: nine elite senior oarsmen, eight former senior oarsmen and eight highly trained athletes unskilled in rowing. The subjects performed graded exercise to maximal effort on a rowing ergometer, cycle ergometer and treadmill while respiratory minute volume
and oxygen consumption
were monitored continuously. The VE at a given
during intense submaximal exercise (greater than 75% of maximal
) was not significantly lower in rowing compared with that in cycling and treadmill running for any group, which would suggest that submaximal rowing does not restrict ventilation. At maximal effort,
and
for rowing were less than those for the other types of exercise in all the groups, although the differences were not statistically significant in the elite oarsmen. These data are consistent with a ventilatory limitation to maximal performance in rowing that may have been partly overcome by training in the elite oarsmen. Alternatively, a lower maximal VE in rowing might have been an effect rather than a cause of a lower maximal
if maximal
was limited by the lower rate of muscle activation in rowing. 相似文献
10.
Daniel T. Clemens 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,158(1):57-66
Summary Rosy finches (Leucosticte arctoa) breed at altitudes above 3500 m in eastern California. House finches (Carpodacus mexicanus) belong to the same subfamily (Carduelinae), but breed at much lower elevations. Oxygen consumption (
) and ventilatory parameters of these two species were measured over a wide range of ambient temperatures (T
a) at low altitude (LA; 150 m) and at high altitude (HA; 3800 m).Minimal nighttime
's of rosy finches and house finches at LA (T
a=30°C) were close to allometrically predicted values for passerine birds. At both altitudes,
increased linearly with decreasingT
a betweenT
a=20 and –10°C. Resting
's were slightly higher at HA than at LA on average.In both species, minute volume (
) was inversely related toT
a.T
a-correlated increases in
resulted from significant increases in both ventilatory frequency (f) and tidal volume (V
T) at both altitudes. Oxygen extraction efficiency (
) was independent ofT
a in rosy finches at LA, but declined significantly with decreasingT
a in rosy finches at HA and in house finches at both altitudes.At a givenT
a, both species had significantly greater
(BTPS) at HA than at LA. Altitude-correlated increases in
resulted primarly from increases inf with little change inV
T.
was significantly greater at HA than at LA in both species.In spite of the difference in altitudinal distributions of rosy finches and house finches, there were few conspicuous interspecific differences in metabolic or ventilatory adaptation to altitude or lowT
a over the range of conditions examined.Symbols and abbreviations
BMR
basal metabolic rate
-
BTPS
at body temperature and pressure, saturated
-
oxygen extraction efficiency
-
f
ventilation frequency
-
h
mean coefficient of heat transfer
-
HA
high altitude
-
instantaneous oxygen consumption
-
LA
low altitude
-
RH
relative humidity
-
SMR
standard metabolic rate
-
STPD
standard temperature and pressure, dry
-
T
temperature
-
a
ambient
-
b
body
-
lc
lower critical of thermoneutral zone
-
minute volume
-
V
T
tidal volume 相似文献
11.
B. Culik A. J. Woakes D. Adelung R. P. Wilson N. R. Coria H. J. Spairani 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(1):61-70
Summary The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O2 consumption (
) and CO2 production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from
in lying chicks to
at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on
were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities (
), and one for walking (
). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as
, whereas mass-specific O2 consumption was related to walking speed (S, m·s-1) as
.Abbreviations
bpm
beats per minute
-
D
distance walked (m)
-
ECG
electrocardiogram
-
HR
heart rate (bpm)
-
ns
number of steps
-
RQ
respiratory quotient
-
S
walking speed (m·s-1)
-
T
time walked (s)
-
W
body mass (kg) 相似文献
12.
Effects of long scotophase and cold acclimation on heat production in two diurnal rodents 总被引:1,自引:1,他引:0
A. Haim 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1982,148(1):77-81
Summary Heat production
of two diurnal rodents,Rhabdomys pumilio andLemniscomys griselda was measured in long scotophase-LS (8L: 16D; 25°C) acclimated and long scotophase and cold — LSAC (8L: 16D; 6°C) acclimated animals and compared to a control group (12L: 12D; 25°C).LS increased
in both species. Further acclimation of LSAC increased
inR. pumilio and decreased
inL. griselda. LS increased body temperature (T
b) inL. griselda only. LS increased overall thermal conductance in both species. LSAC caused a further increase in this parameter inR. pumilio.A singificant (P<0.001) increase in the magnitude of maximal nonshivering thermogenesis (NST) was observed in both species due to LS acclimation. LSAC did not change this maximal NST but increased its obligatory part (minimal
, P<0.05, inL. griselda, andP<0.001, inR. pumilio).The results of this study show that winter acclimatization of heat production mechanisms, in both species, may be due to extension of scotophase.Abbreviations
LS
long scotophase
-
LSAC
long scotophase and cold
-
NA
noradrenaline
-
NST
nonshivering thermogenesis
-
RMR
resting metabolic rate 相似文献
13.
Mark A. Chappell Tamir M. Ellis 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(2):227-235
Summary Resting metabolic rates (RMR) of 34 species from 18 genera of boas and pythons (Serpentes: Boidae), with body masses ranging from 2 to 67,800 g, were determined as oxygen consumption (
) and carbon dioxide production (
) at three ambient temperatures (T
a).The temperature coefficient of metabolism (Q10) averaged 2.61 betweenT
a of 20–30°C and 2.65 between 30 and 34°C. The respiratory exchange ratio RE (=
/
) increased slightly with increasingT
a (0.795 at 20°C, 0.819 at 30°C, and 0.834 at 34°C). Interspecific differences in Q10 and RE were slight or insignificant.A multiple regression relating metabolism (
) to mass andT
a explained 97% of the variance in the pooled interspecific data. The mass exponent was 0.806, which is approximately the same as reported for squamates and for all reptilian taxa combined. The mean within-species slope (0.732) was significantly less than the slope for pooled data, but did not differ significantly from 0.75. In 40 of 42 cases (14 species at 3T
a), within-species slopes did not differ from each other. Values of the adjusted mean Y, from covariance analysis, were significantly and positively correlated with mass, indicating that the mass coefficient increases with increasing mass.Considerable variation in metabolic rate is apparent both within and between ecological and taxonomic categories.Original metabolic data are available from the National Auxiliary Publications Services, c/o Microfiche Publication, P.O. Box 3153 Grand Central Station, New York, New York 10017, USA 相似文献
14.
W. Selvamurthy U. S. Ray K. S. Hegde R. P. Sharma 《International journal of biometeorology》1988,32(3):188-193
A study was conducted on 30 healthy soldiers (age: 40–46 years) to assess the effect of selected yogic exercises (asanas) on some physiological responses to cold exposure. They were randomly divided into two groups of 15 each. One group performed regular physical exercises of physical training (PT), while the other group practised yogic exercises. At the end of 6 months of training, both the groups were exposed together to cold stress at 10°C for 2 h, and the following parameters were periodically monitored during cold exposure: heart rate (fH), blood pressure (BP), cardiac output
, oral temperature (Tor), skin temperature (T
sk), respiratory rate (fR), minute ventilation
, oxygen consumption
, and shivering response by integrated electromyogram (EMG). There were progressive increases inBP, fR,
,
, and
and decreases infH,T
or andT
sk during cold exposure in both the groups. However, the decrease inT
or and the increases in
and
were relatively lower (P<0.01) in the yoga group as compared to the PT group. The shivering response appeared much earlier and was more intense in the PT group. These findings suggest that practice of yoga exercises may improve cold tolerance. 相似文献
15.
Theodore L. Taigen Kentwood D. Wells 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(2):163-170
Summary The metabolic demands of vocalization byHyla versicolor were determined by measuring oxygen consumption and whole body lactate content of calling animals. A stepwise multiple regression analysis identified both calling rate (calls/h) and call duration (s/call) as significant determinants of oxygen consumption during calling. These two variables accounted for 84% of the total variation in oxygen consumption observed in calling frogs. Aerobic metabolism
increased linearly with calling rate and call duration, reaching a peak value of 1.7 ml O2/(g·h) at the highest vocalization effort. For comparison, metabolic rates of the same individuals were also measured during short bouts of vigorous locomotor exercise
induced by mechanical stimulation. The mean value of
was only 62% of the peak
, and 5 of 13 frogs had rates of oxygen consumption during calling that exceeded their
. Whole body lactate levels were measured in two samples of calling frogs, one collected early in the evening (2100–2115 h) and the other 1.5 h later (2230–2245 h). The frogs in the second sample had significantly lower lactate levels (0.10 mg/g) than the frogs collected early in the evening (0.22 mg/g). Hence, vocalization does not entail the use of anaerobic metabolism, although lactate levels may be slightly elevated at the onset of an evening of calling. Calling rates of unrestrained frogs in a large chorus were measured at regular intervals during an evening. During the first half hour of calling, rates increased gradually from an initial mean value of 600 calls/h at 2030 h to nearly 1400 calls/h at 2100 h. These data indicate that acoustic advertisement byHyla versicolor is among the most energetically expensive activities regularly undertaken by any anuran, and indeed, is the most demanding yet measured in an ectothermic vertebrate.Abbreviations
resting rate of oxygen consumption
-
maximum rate of oxygen consumption
-
rate of oxygen consumption during forced exercise
-
rate of oxygen consumption during calling 相似文献
16.
Pierre Dejours Jean-Paul Truchot 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,158(3):387-391
Summary In the intertidal shore crab,Carcinus maenas, pH and
values of the prebranchial venous hemolymph,
and
, the PO2 values of the arterialized cardiac hemolymph,
, were measured, and the ventilatory activity was assessed by measuring the hydrostatic pressures at the exits of the epibranchial cavities, under four environmental conditions: normoxic water, normoxic air, hypoxic gas, hyperoxic gas.In the crab breathing normoxic air,
was lower and
higher than in animals breathing normoxic water. With the switch to hypoxic gas, ventilation increased and
and
decreased. With the switch to hyperoxic gas, ventilation decreased,
and
increased and
decreased.Thus these crabs breathing air were not as well oxygenated as when breathing air-equilibrated water, and because of their low
, they were relatively hypervetilating and hypocapnic compared to air-breathing vertebrates. Hyperoxic breathing, increasing
and reducing ventilatory drive, led to increased
. Conversely,
was reduced by hypoxic breathing. These observations suggest that the gas exchanger of intertidal crabs is not as successfully designed for air breathing as that of land-colonizing insects and air-breathing vertebrates. 相似文献
17.
Thermoregulation,gas exchange,and ventilation in Adelie penguins (Pygoscelis adeliae) 总被引:1,自引:0,他引:1
Mark A. Chappell Sherrie L. Souza 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):783-790
Summary Adelie penguins (Pygoscelis adeliae) experience a wide range of ambient temperatures (T
a) in their natural habitat. We examined body temperature (T
b), oxygen consumption (
), carbon dioxide production (
), evaporative water loss (
), and ventilation atT
a from –20 to 30 °C. Body temperature did not change significantly between –20 and 20°C (meanT
b=39.3°C).T
b increased slightly to 40.1 °C atT
a=30°C. Both
and
were constant and minimal atT
a between –10 and 20°C, with only minor increases at –20 and 30°C. The minimal
of adult penguins (mean mass 4.007 kg) was 0.0112 ml/[g·min], equivalent to a metabolic heat production (MHP) of 14.9 Watt. The respiratory exchange ratio was approximately 0.7 at allT
a. Values of
were low at lowT
a, but increased to 0.21 g/min at 30°C, equivalent to 0.3% of body mass/h. Dry conductance increased 3.5-fold between –20 and 30°C. Evaporative heat loss (EHL) comprised about 5% of MHP at lowT
a, rising to 47% of MHP atT
a=30°C. The means of ventilation parameters (tidal volume [VT], respiration frequency [f], minute volume [I], and oxygen extraction [
]) were fairly stable between –20 and 10°C (VT did not change significantly over the entireT
a range). However, there was considerable inter- and intra-individual variation in ventilation patterns. AtT
a=20–30°C,f increased 7-fold over the minimal value of 7.6 breaths/min, and I showed a similar change.
fell from 28–35% at lowT
a to 6% atT
a=30°C.Abbreviations
C
thermal conductance
-
EHL
evaporative heat loss
-
oxygen extraction
-
f
respiratory frequency
-
MHP
metabolic heat production
-
evaporative water loss
-
LCT
lower critical temperature
-
RE
respiratory exchange ratio
-
T
a
ambient temperature
-
T
b
body temperature
-
rate of oxygen consumption
-
rate of carbon dioxide production
- I
inspiratory minute volume
-
VT
tidal volume 相似文献
18.
S. D. R. Galloway M. S. Tremblay J. R. Sexsmith C. J. Roberts 《European journal of applied physiology and occupational physiology》1996,72(3):224-230
Six trained cyclists (high-fitness group) and six untrained individuals (low-fitness group), performed a 20-min cycle ergometer exercise test at 70% of maximum oxygen consumption (
followed by a 30-min rest period and then an incremental ride to exhaustion on two occasions, 1 week apart. Ninety minutes prior to exercise subjects consumed a drink containing either 22.2 g dibasic calcium phosphate (DCP; treatment) or calcium carbonate (placebo). Blood was drawn prior to drink ingestion, during submaximal exercise, during recovery and at exhaustion for determination of blood 2,3-DPG, blood ATP, plasma lactate, plasma phosphate, haemoglobin and haematocrit. Throughout exercise, cardiorespiratory variables [oxygen uptake (
minute ventilation, (
), respiratory exchange ratio, heart rate and oxygen pulse] were monitored, and ratings of perceived exertion obtained. Although there was a trend for the low-fitness group to have a higher plasma phosphate concentration prior to treatment ingestion, no treatment effects on plasma phosphate were noted at any sample time in either group. 2,3-DPG,
oxygen pulse,
time to exhaustion and
were significantly higher in the high-fitness group; however, no differences in these variables were observed as a result of phosphate ingestion. Plasma lactate was significantly lower in the high-fitness group during the submaximal exercise and the recovery period, but again phosphate ingestion had no effect. These results suggest that acute DCP supplementation is not effective as an ergogenic aid and that aerobic fitness level does not affect the response to phosphate supplementation. 相似文献
19.
Chappell Mark A. Bucher Theresa L. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(1):129-136
Summary The effects of ambient temperature (T
a) on ventilation and gas exchange in chukar partridges (Alectoris chukar) were determined after acclimation to low and high altitute (LA and HA; 340 and 3,800 m, respectively).At both LA and HA, oxygen consumption (
) increased with decreasingT
a atT
a from 20 to –20°C. AtT
a of 35 to 40°C,
increased above thermoneutral values at HA but remained constant and minimal at LA. Water loss rates increased rapidly atT
a>30°C at both altitudes as birds began to pant. Ventilation rates (f) during panting were 5-to 23-fold greater than the minimalf at thermoneutralT
a.Increased
atT
a below thermoneutrality was supported by increased minute volume (V
i) at both altitudes. The change inV
i was primarily a function of changing tidal volume (V
t), althoughf increased slightly asT
a declined. Oxygen extraction (
) remained fairly constant atT
a below 20°C at both altitudes. BothV
t and
were considerably lower when birds were panting than at lowerT
a.Chukars showed few obvious ventilatory adaptations to HA. The 35% change in
between 340 and 3,800 m was accommodated by a corresponding change inV
i (btps), most of which was accomplished by increasedf at HA, along with a slight increase in
.Abbreviations and symbols
HA
high altitude
-
LA
low altitude
-
rate of evaporative water loss
-
oxygen extraction efficiency
-
f
respiratory frequency
-
V
t
tidal volume
-
V
i
minute volume
-
BMR
basal metabolic rate
-
MHP
metabolic heat production 相似文献
20.
Effects of ambient temperature and altitude on ventilation and gas exchange in deer mice (Peromyscus maniculatus) 总被引:2,自引:1,他引:1
Mark A. Chappell 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(6):751-758
Summary The effects of different ambient temperatures (T
a) on gas exchange and ventilation in deer mice (Peromyscus maniculatus) were determined after acclimation to low and high altitude (340 and 3,800 m).At both low and high altitude, oxygen consumption (
) decreased with increasingT
a atT
a from –10 to 30 °C. The
was 15–20% smaller at high altitude than at low altitude atT
a below 30 °C.Increased
atT
a below thermoneutrality was supported by increased minute volume (
) at both low and high altitude. At mostT
a, the change in
was primarily a function of changing respiration frequency (f); relatively little change occurred in tidal volume (V
T) or oxygen extraction efficiency (O2EE). AtT
a=0 °C and below at high altitude,
was constant due to decliningV
T and O2EE increased in order to maintain high
.At high altitude,
(BTP) was 30–40% higher at a givenT
a than at low altitude, except atT
a below 10 °C. The increased
at high altitude was due primarily to a proportional increase inf, which attained mean values of 450–500 breaths/min atT
a below 0 °C. The
(STP) was equivalent at high and low altitude atT
a of 10 °C and above. At lowerT
a,
(STPD) was larger at low altitude.At both altitudes, respiratory heat loss was a small fraction (<10%) of metabolic heat production, except at highT
a (20–30 °C).Abbreviations
EHL
evaporative heat loss
-
f
respiration frequency
-
HL
a
heat loss from warming tidal air
-
HL
e
evaporative heat loss in tidal air
-
HL
total respiratory heat loss
-
MHP
metabolic heat production
-
O
2
EE
oxygen extraction efficiency
-
RQ
respiratory quotient
-
T
a
ambient temperature
-
T
b
body temperatureT
lc lower critical temperature
-
carbon dioxide production
-
evaporative water loss
-
oxygen consumption
-
minute volume
-
V
T
tidal volume 相似文献