Heterothermy, torpor, respiratory gas exchange, water balance and the effect of feeding in Gould's long-eared bat Nyctophilus gouldi.

1994 ◽  
Vol 197 (1) ◽  
pp. 309-335
Author(s):  
S Morris ◽  
A L Curtin ◽  
M B Thompson
Keyword(s):  
Body Temperature ◽  
Gas Exchange ◽  
Nutritional Status ◽  
Metabolic Rate ◽  
Water Loss ◽  
Respiratory Exchange Ratio ◽  
Thermal Conductance ◽  
Evaporative Water ◽  
Effects Of Temperature ◽  
Effect Of Feeding

The effects of temperature and nutritional status on the metabolic rate of Nyctophilus gouldi were examined. Bats fed marked meals first defecated approximately 1.34 h after feeding and were calculated to have a mean retention time of 5.38 +/- 0.57 h but to be truly post-absorptive after 9 h. Over the temperature range 1-35 degrees C, the metabolic rate (Vo2) and body temperature (Tb) of fasted bats were extremely labile. Below 30 degrees C, the bats all entered torpor and between 10 and 15 degrees C showed a mean 84% reduction over the maximal Vo2. Body temperature was also minimal over this range (Tb = 12.5 degrees C, Ta = 10-15 degrees C). Both total and dry thermal conductance increased in a curvilinear manner with temperature, total conductance from 3.38 +/- 0.65 J g-1 h-1 degree C-1 at 1 degree C to 24.25 +/- 1.99 J g-1 h-1 degree C-1 at 35 degrees C (mean +/- S.E.M.), while the rate of evaporative water loss increased with Ta by a maximum of 10-fold from 0.21 mg g-1 h-1 at 5 degrees C to 2.69 mg g-1h-1 at 35 degrees C. Between 10 and 25 degrees C, intermittent respiration characterised by episodic bouts of breathing/gas exchange and periods of apnoea with no measurable Vo2 occurred. Although the duration of apnoea decreased when temperature was increased, the volume of oxygen taken up in each episode did not change. Mean respiratory exchange ratio (RER) was low (0.64-0.77) in post-absorptive bats, typical of fat utilisation, but during torpor ranged from near 0 to near 2, indicating discontinuous and disproportional gas exchange. Feeding produced a condition of relatively sustained homeothermy and high RER in the bats which persisted for 9 h, after which the N. gouldi became torpid. Immediately after feeding, the Vo2 of the bats increased fivefold above the post-absorptive level, while the Vco2 increased by more than eightfold. Similarly, body temperature also increased, declining to torpid values after 9. The RER in immediately post-feeding bats was near 1.0 but subsequently declined to near 0.7, indicating a switch from carbohydrate to fat utilisation. Therefore, the N. gouldi were heterothermic, exhibited a highly labile metabolic rate, and rates of heat and water loss, and Tb which were influenced both by ambient temperature and by nutritional status.

Metabolism, Water-Balance and Temperature Regulation in the Golden Bandicoot (Isoodon-Auratus)

1992 ◽  
Vol 40 (5) ◽  
pp. 523 ◽  
Author(s):  
PC Withers
Keyword(s):  
Body Temperature ◽  
Water Balance ◽  
Metabolic Rate ◽  
Basal Metabolic Rate ◽  
Temperature Regulation ◽  
Water Loss ◽  
Thermal Conductance ◽  
Evaporative Water Loss ◽  
Evaporative Water ◽  
Low Rate

The Barrow I. golden bandicoot (Isoodon auratus) is a small arid-adapted marsupial. It has a low and labile body temperature, a low basal metabolic rate, a low thermal conductance, and a low rate of evaporative water loss. Its metabolic, thermal and hygric physiology resembles that of another arid-adapted bandicoot, the bilby, and differs from temperate and tropical bandicoots.

scholarly journals Water Costs of Gas Exchange by a Speckled Cockroach and a Darkling Beetle

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 632
Author(s):  
Waseem Abbas ◽  
Philip C. Withers ◽  
Theodore A. Evans
Keyword(s):  
Body Size ◽  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Evaporative Water ◽  
Factors Affecting ◽  
Darkling Beetle ◽  
Terrestrial Insects ◽  
Exchange Patterns ◽  
Respiratory Cost

Respiratory water loss during metabolic gas exchange is an unavoidable cost of living for terrestrial insects. It has been suggested to depend on several factors, such as the mode of gas exchange (convective vs. diffusive), species habitat (aridity), body size and measurement conditions (temperature). We measured this cost in terms of respiratory water loss relative to metabolic rate (respiratory water cost of gas exchange; RWL/V˙CO2) for adults of two insect species, the speckled cockroach (Nauphoeta cinerea) and the darkling beetle (Zophobas morio), which are similar in their mode of gas exchange (dominantly convective), habitat (mesic), body size and measurement conditions, by measuring gas exchange patterns using flow-through respirometry. The speckled cockroaches showed both continuous and discontinuous gas exchange patterns, which had significantly a different metabolic rate and respiratory water loss but the same respiratory water cost of gas exchange. The darkling beetles showed continuous gas exchange pattern only, and their metabolic rate, respiratory water loss and respiratory cost of gas exchange were equivalent to those cockroaches using continuous gas exchange. This outcome from our study highlights that the respiratory water cost of gas exchange is similar between species, regardless of gas exchange pattern used, when the confounding factors affecting this cost are controlled. However, the total evaporative water cost of gas exchange is much higher than the respiratory cost because cuticular water loss contributes considerably more to the overall evaporative water loss than respiratory water. We suggest that the total water cost of gas exchange is likely to be a more useful index of environmental adaptation (e.g., aridity) than just the respiratory water cost.

Inhibitors of nitric oxide synthesis block cold-induced thermogenesis in rats

2003 ◽  
Vol 81 (8) ◽  
pp. 834-838 ◽  
Author(s):  
Peter R Kamerman ◽  
Helen P Laburn ◽  
Duncan Mitchell
Keyword(s):  
Nitric Oxide ◽  
Methyl Ester ◽  
Body Temperature ◽  
Nitric Oxide Synthase ◽  
Metabolic Rate ◽  
Water Loss ◽  
T Test ◽  
Evaporative Water Loss ◽  
Evaporative Water ◽  
Oxide Synthase

N-nitro-L-arginine methyl ester (L-NAME), an unspecific nitric oxide synthase inhibitor, was administered to individually caged Sprague–Dawley rats exposed to cold (18°C) and thermoneutral (30°C) environmental temperatures during the active phase of the animals' circadian cycle. Unrestrained rats were administered intraperitoneal injections of 100 mg·kg–1 L-NAME or 1 mL·kg–1 saline. Telemetry was used to measure abdominal temperature. On a separate occasion, metabolic rate and evaporative water loss were measured using indirect calorimetery, before and after the injection of 100 mg·kg–1 L-NAME, in rats exposed to the two environments. Injection of L-NAME had no significant effect on body temperature, metabolic rate, or evaporative water loss in rats exposed to the 30°C environment. In the 18°C environment, L-NAME injection caused a prolonged fall in body temperature (F(1,12) = 17.43, P = 0.001) and a significant decrease in metabolic rate (Student's t test, P = 0.001) and evaporative water loss (one-sample t test, P = 0.04). Therefore, the effects that systemic injection of L-NAME has on body temperature are dependent on environmental temperature, with nitric oxide synthase inhibition seemingly preventing the metabolic component of cold defence.Key words: N-nitro-L-arginine methyl ester, thermoregulation, telemetry, oxygen consumption.

Thermoregulatory, metabolic and ventilatory physiology of the eastern barred bandicoot (Perameles gunnii)

2006 ◽  
Vol 54 (1) ◽  
pp. 9 ◽  
Author(s):  
Alexander N. Larcombe ◽  
Philip C. Withers ◽  
Stewart C. Nicol
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Basal Metabolic Rate ◽  
Extraction Efficiency ◽  
Thermal Conductance ◽  
Minute Volume ◽  
Evaporative Water ◽  
Ambient Temperatures ◽  
Ventilatory Parameters ◽  
High Basal Metabolic Rate

Thermoregulatory, metabolic and ventilatory parameters measured for the Tasmanian eastern barred bandicoot (Perameles gunnii) in thermoneutrality (ambient temperature = 30°C) were: body temperature 35.1°C, basal metabolic rate 0.55 mL O2 g–1 h–1, wet thermal conductance 2.2 mL O2 g–1 h–1 °C–1, dry thermal conductance 1.4 J g–1 h–1 °C–1, ventilatory frequency 24.8 breaths min–1, tidal volume 9.9 mL, minute volume of 246 mL min–1, and oxygen extraction efficiency 22.2%. These physiological characteristics are consistent with a cool/wet distribution, e.g. high basal metabolic rate (3.33 mL O2 g–0.75 h–1) for thermogenesis, low thermal conductance (0.92 J g–1 h–1 °C–1 at 10°C) for heat retention and intolerance of high ambient temperatures (≥35°C) with panting, hyperthermia and high total evaporative water loss (16.9 mg H2O g–1 h–1).

scholarly journals The role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern African anurans of different habitat specialisation

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7885 ◽  
Author(s):  
Mohlamatsane Mokhatla ◽  
John Measey ◽  
Ben Smit
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Body Mass ◽  
Water Loss ◽  
Standard Metabolic Rate ◽  
Evaporative Water Loss ◽  
Evaporative Water ◽  
Habitat Specialisation ◽  
Wide Range

Temperature and water availability are two of the most important variables affecting all aspects of an anuran’s key physiological processes such as body temperature (Tb), evaporative water loss (EWL) and standard metabolic rate (SMR). Since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (VPD), sex and body mass (Mb). However, a limited number of studies have tested the generality of these results across a wide range of ecologically relevant ambient temperatures (Ta), while taking habitat use into account. Thus, the aim of this study was to investigate the role of Ta on Tb, whole-animal EWL and whole-animal SMR in three wild caught African anuran species with different ecological specialisations: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis). Experiments were conducted at a range of test temperatures (5–35 °C, at 5 °C increments). We found that VPD better predicted rates of EWL than Ta in two of the three species considered. Moreover, we found that Tb, whole-animal EWL and whole-animal SMR increased with increasing Ta, while Tb increased with increasing Mb in A. delalandii and S. capensis but not in X. laevis. Whole-animal SMR increased with increasing Mb in S. capensis only. We did not find any significant effect of VPD, Mb or sex on whole-animal EWL within species. Lastly, Mb did not influence Tb, whole-animal SMR and EWL in the principally aquatic X. laevis. These results suggest that Mb may not have the same effect on key physiological variables, and that the influence of Mb may also depend on the species ecological specialisation. Thus, the generality of Mb as an important factor should be taken in the context of both physiology and species habitat specialisation.

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