THE CALORIGENIC RESPONSE OF COLD-ACCLIMATED WHITE RATS TO INFUSED NORADRENALINE

The increase in oxygen consumption during continuous intravenous injection of various doses of L-noradrenaline was measured in anesthetized rats fully acclimated to 6 °C. The metabolic response was found to be linearly related to the logarithm of the amount of noradrenaline infused per minute. The calorigenic response to infusion of noradrenaline at a level of 1 μg per minute was then measured in rats undergoing acclimation to cold. The calorigenic response was found to increase with time of exposure to the cold environment, thus paralleling previous observations in the time course of gain in cold resistance, increase in food consumption, and loss of dependence on shivering during acclimation of white rats to cold. Also, the same maximal increase in oxygen consumption was obtained on infusion of noradrenaline into functionally eviscerated and sham-operated cold-acclimated rats, thus indicating that the liver and other abdominal viscera (kidneys excluded) are not involved in the calorigenic response to noradrenaline. It is proposed, as a working hypothesis, that striated muscle is the site of the major alteration in sensitivity to noradrenaline induced by acclimation to cold. Difficulties associated with consideration of striated muscle as the source of non-shivering thermogenesis in the cold-acclimated rat are discussed.

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SEASONAL ADJUSTMENTS IN CAPTURED WILD NORWAY RATS: II. SURVIVAL TIME, PELT INSULATION, SHIVERING, AND METABOLIC AND PRESSOR RESPONSES TO NORADRENALINE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y62-063 ◽

1962 ◽

Vol 40 (1) ◽

pp. 537-545 ◽

Cited By ~ 8

Author(s):

O. Héroux ◽

Donna Wright

Keyword(s):

Survival Time ◽

Metabolic Response ◽

Cold Temperature ◽

White Rats ◽

Winter Conditions ◽

Pressor Responses ◽

Wild Rats ◽

Norway Rats ◽

Shivering Thermogenesis

During the winter, wild rats (Rattus norwegicus) develop metabolic adjustments similar to those found in the white rats acclimated to cold in the laboratory. The rate of shivering found in the winter-captured wild rats is lower than that found in the summer-captured rats, indicating the presence of non-shivering thermogenesis. The metabolic response to noradrenaline is enhanced suggesting that non-shivering metabolism in these wild rats, as in the case of white rats, is mediated by noradrenaline. Unlike white rats acclimated to a constant cold temperature in the laboratory, but like white rats acclimatized to cold by group exposure to outdoor winter conditions, wild rats develop a greater pelt insulation in winter.

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SEASONAL ADJUSTMENTS IN CAPTURED WILD NORWAY RATS: II. SURVIVAL TIME, PELT INSULATION, SHIVERING, AND METABOLIC AND PRESSOR RESPONSES TO NORADRENALINE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o62-063 ◽

1962 ◽

Vol 40 (4) ◽

pp. 537-545 ◽

Cited By ~ 17

Author(s):

O. Héroux ◽

Donna Wright

Keyword(s):

Survival Time ◽

Metabolic Response ◽

Cold Temperature ◽

White Rats ◽

Winter Conditions ◽

Pressor Responses ◽

Wild Rats ◽

Norway Rats ◽

Shivering Thermogenesis

During the winter, wild rats (Rattus norwegicus) develop metabolic adjustments similar to those found in the white rats acclimated to cold in the laboratory. The rate of shivering found in the winter-captured wild rats is lower than that found in the summer-captured rats, indicating the presence of non-shivering thermogenesis. The metabolic response to noradrenaline is enhanced suggesting that non-shivering metabolism in these wild rats, as in the case of white rats, is mediated by noradrenaline. Unlike white rats acclimated to a constant cold temperature in the laboratory, but like white rats acclimatized to cold by group exposure to outdoor winter conditions, wild rats develop a greater pelt insulation in winter.

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COMPARISON BETWEEN SEASONAL AND THERMAL ACCLIMATION IN WHITE RATS: V. METABOLIC AND CARDIOVASCULAR RESPONSE TO NORADRENALINE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o61-203 ◽

1961 ◽

Vol 39 (12) ◽

pp. 1829-1836 ◽

Cited By ~ 23

Author(s):

O. Héroux

Keyword(s):

Blood Pressure ◽

Oxygen Consumption ◽

Intramuscular Injection ◽

Cold Resistance ◽

Cardiovascular Response ◽

Great Sensitivity ◽

Slight Degree ◽

White Rats ◽

Winter Conditions ◽

Indoor And Outdoor

White rats cold-acclimated at a constant temperature in the laboratory are known to be more sensitive to noradrenaline than warm-acclimated controls. The present study reveals that this responsiveness to noradrenaline is linearly related to the temperature at which the animals are conditioned. Concomitant measurements (after intramuscular injection of noradrenaline) of oxygen consumption, blood pressure, and heart rates on white rats acclimatized to outdoor summer or winter conditions revealed a much greater metabolic and cardiovascular sensitivity to noradrenaline in winter than in summer rats. The slight degree of shivering upon exposure to 6 °C which was observed in the outdoor winter rats, as well as their great sensitivity to noradrenaline, suggests that under both indoor and outdoor environmental conditions, increased cold resistance is obtained through similar metabolic mechanisms.

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Metabolic rate responses to cold and to exogenous noradrenaline in newborn Scottish Blackface lambs genetically selected for high or low resistance to cold

Animal Science ◽

10.1017/s0003356100036631 ◽

1987 ◽

Vol 45 (1) ◽

pp. 69-74 ◽

Cited By ~ 14

Author(s):

J. Slee ◽

S. P. Simpson ◽

J. A. Woolliams

Keyword(s):

Genetic Variation ◽

Metabolic Rate ◽

Cold Exposure ◽

Cold Resistance ◽

Metabolic Response ◽

Genetic Selection ◽

Subcutaneous Injections ◽

The Difference ◽

Body Cooling ◽

Shivering Thermogenesis

AbstractNewborn Scottish Blackface lambs from lines previously selected for high (H) or low (L) resistance to body cooling were tested for their metabolic response (O2 consumption) to cold exposure in a water bath or to subcutaneous injections of exogenous noradrenaline as a measure of non-shivering thermogenesis (NST). Six rams from the H line and six rams from the L line were used to produce lambs such that each sire had both cold-tested (no. = 48) and noradrenaline-tested (no. = 86) progeny.The mean elevations in metabolic rate produced by cold exposure and by noradrenaline were, respectively, 3·4 times and 2·4 times resting (thermoneutral) metabolic rate. H lambs showed significantly greater cold resistance and metabolic response to cold than L lambs. H lambs showed greater NST than L lambs but the difference was not significant. There were significant sire effects on NST, indicating genetic variation. There was a significant correlation between the metabolic responses to cold and those o t noradrenaline among the sire progeny groups. NST capability appears to be a phenotypic component of neonatal cold resistance which would respond to genetic selection, but this genetic variation is not a major component of that determining cold resistance.

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Effect of meal size on postprandial metabolic response and excess post-exercise oxygen consumption in juvenile rock carp (Procypris rabaudi)

JOURNAL OF FISHERIES OF CHINA ◽

10.3724/sp.j.1231.2012.27783 ◽

2012 ◽

Vol 36 (11) ◽

pp. 1731 ◽

Cited By ~ 1

Author(s):

Xiu-ming LI ◽

Chang-rui CHEN ◽

Chuan WU ◽

Shi-jian FU ◽

Yao-guang ZHANG

Keyword(s):

Oxygen Consumption ◽

Metabolic Response ◽

Meal Size ◽

Post Exercise ◽

Procypris Rabaudi

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

Sensors ◽

10.3390/s21051748 ◽

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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Influence of cycloheximide on the lung

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.4.623 ◽

1975 ◽

Vol 38 (4) ◽

pp. 623-629 ◽

Cited By ~ 9

Author(s):

D. B. Gail ◽

G. D. Massaro ◽

D. Massaro

Keyword(s):

Oxygen Consumption ◽

Surface Density ◽

Time Course ◽

Lamellar Body ◽

Lamellar Bodies ◽

Cytoplasmic Area ◽

The Right

We examined the time course of the influence of cycloheximide on descending pressure-volume curves of excised lungs and on protein and lecithin synthesis and oxygen consumption by lung slices. We also looked at the influence of cycloheximide on granular pneumocyte ultrastructure. Excised lungs from cycloheximide-treated animals are more compliant than controls. After ventilation with air, lungs from control and cycloheximide animals show increased retractive forces and a shift to the right of the deflation P-V curve. Incubation at 38 degrees C for 30 min reverses these changes in control lungs, but not in lungs from cycloheximide-treated rabbits. There is no change in liquid delfation P-V curves after cycloheximide. Cycloheximide causes an immediate decrease of 50% in incorporation of radioactive leucine into protein by lung slices. Incorporation of radioactive palmitate into lecithin and oxygen consumption are also decreased by 50% 6 h after cycloheximide. Lamellar bodies in granular pneumocytes are smaller after cycloheximide. Cycloheximide causes a significant increase in the surface density of the lamellar body envelope. Cytoplasmic area of granular pneumocytes is increased after cycloheximide.

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Isolation of a chitinase overproducing mutant of Streptomyces peucetius defective in daunorubicin biosynthesis

Canadian Journal of Microbiology ◽

10.1139/w00-079 ◽

2000 ◽

Vol 46 (10) ◽

pp. 956-960 ◽

Cited By ~ 2

Author(s):

Kuzhandhaivel S Vetrivel ◽

Kuppamuthu Dharmalingam

Keyword(s):

Biosynthetic Pathway ◽

Time Course ◽

Polyketide Synthase ◽

Protein Profile ◽

Restriction Enzymes ◽

Wild Type ◽

Anthracycline Antibiotic ◽

Streptomyces Peucetius ◽

Chitinase Production ◽

Major Alteration

Streptomyces peucetius, producer of the antitumor anthracycline antibiotic daunorubicin, was mutagenized, and mutants defective in daunorubicin biosynthesis were screened. One mutant (SPVI), which failed to produce daunorubicin, was found to overproduce an extracellular chitinase. Time course analyses of chitinase production and of the extracellular protein profile showed that the increase in activity is due to increased synthesis of the enzyme protein. The production of chitinase in SPVI was repressed by glucose as in the case of wild-type S. peucetius. PFGE analysis of VspI restriction fragments of S. peucetius and SPVI showed that there was no major alteration in the mutant genome. The hybridization pattern of S. peucetius and SPVI genomic DNA digested with various restriction enzymes was identical when probed with dnrUVJI genes of the S. peucetius daunorubicin cluster and chiA of Streptomyces lividans 66. The possible step affected in the daunorubicin biosynthetic pathway could be a polyketide synthase, since aklanonic acid, the earliest detectable intermediate in the daunorubicin pathway, was not synthesized in SPVI.Key words: Streptomyces peucetius, chitinase, daunorubicin, NTG mutagenesis.

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The metabolic response of the Bradypus sloth to temperature

PeerJ ◽

10.7717/peerj.5600 ◽

2018 ◽

Vol 6 ◽

pp. e5600 ◽

Cited By ~ 6

Author(s):

Rebecca Naomi Cliffe ◽

David Michael Scantlebury ◽

Sarah Jane Kennedy ◽

Judy Avey-Arroyo ◽

Daniel Mindich ◽

...

Keyword(s):

Oxygen Consumption ◽

Body Temperature ◽

Energy Expenditure ◽

High Power ◽

Metabolic Response ◽

Metabolic Responses ◽

Metabolic Depression ◽

Wide Range ◽

Energetic Constraints ◽

Power Costs

Poikilotherms and homeotherms have different, well-defined metabolic responses to ambient temperature (Ta), but both groups have high power costs at high temperatures. Sloths (Bradypus) are critically limited by rates of energy acquisition and it has previously been suggested that their unusual departure from homeothermy mitigates the associated costs. No studies, however, have examined how sloth body temperature and metabolic rate vary with Ta. Here we measured the oxygen consumption (VO2) of eight brown-throated sloths (B. variegatus) at variable Ta’s and found that VO2 indeed varied in an unusual manner with what appeared to be a reversal of the standard homeotherm pattern. Sloth VO2 increased with Ta, peaking in a metabolic plateau (nominal ‘thermally-active zone’ (TAZ)) before decreasing again at higher Ta values. We suggest that this pattern enables sloths to minimise energy expenditure over a wide range of conditions, which is likely to be crucial for survival in an animal that operates under severe energetic constraints. To our knowledge, this is the first evidence of a mammal provisionally invoking metabolic depression in response to increasing Ta’s, without entering into a state of torpor, aestivation or hibernation.

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