Effects of oxygen inhalation on responses to cold exposure

The effects of oxygen inhalation on shivering and thermal and metabolic responses to exposure to cold (10 C) were determined in ten healthy male subjects. The results showed that oxygen breathing reduced shivering and promoted a feeling of greater comfort. The ventilatory response to cold was diminished, and oxygen consumption was significantly lower during the later periods of the cold exposure. Carbon dioxide production was reduced and the mobilization of nitrogen during the initial periods of cold exposure was also noted. Since body temperatures and their rates of fall were not significantly altered by oxygen inhalation, a shift to more efficient metabolic heat production seems indicated. Submitted on February 6, 1961

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EFFECT OF OXYGEN ON THE REGIONAL DISTRIBUTION OF VENTILATION AND PERFUSION IN THE LUNG

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y66-010 ◽

1966 ◽

Vol 44 (1) ◽

pp. 89-93 ◽

Cited By ~ 11

Author(s):

H. S. Holley ◽

A. Dawson ◽

A. C. Bryan ◽

J. Milic-Emili ◽

D. V. Bates

Keyword(s):

Regional Distribution ◽

Healthy Male ◽

Regional Ventilation ◽

Oxygen Breathing ◽

Lower Lung ◽

Effect Of Oxygen ◽

Breathing Room ◽

Male Subjects ◽

Ventilation And Perfusion ◽

Measure Distribution

Xenon133 was used to measure distribution of ventilation and perfusion in the upper, middle, and lower lung zones of 12 upright healthy male subjects, at rest and during exercise, while breathing room air and after breathing 100% oxygen for 20 minutes. During the breathing of both air and 100% oxygen, ventilation and perfusion increased from the apex to the base of the lung, the differences between upper and lower zones becoming less pronounced during exercise. Oxygen breathing did not appear to affect distribution of regional ventilation or perfusion in normal upright man, either at rest or during exercise. This negative result is of importance in relation to the possible role in intact man of homeostatic mechanisms of adjusting perfusion and ventilation, which are sensitive to oxygen tension.

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Effects of modafinil on heat thermoregulatory responses in humans at rest

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y02-092 ◽

2002 ◽

Vol 80 (8) ◽

pp. 796-803 ◽

Cited By ~ 3

Author(s):

Jean-Claude Launay ◽

Yves Besnard ◽

Angélique Guinet ◽

Germain Bessard ◽

Christian Raphel ◽

...

Keyword(s):

Heat Storage ◽

Sweat Rate ◽

Heat Exposure ◽

Body Temperatures ◽

Metabolic Heat ◽

Thermoregulatory Responses ◽

The Central Nervous System ◽

Male Subjects ◽

Skin Temperatures ◽

Body Heat

The effects of modafinil on heat thermoregulatory responses were studied in 10 male subjects submitted to a sweating test after taking 200 mg of modafinil or placebo. Sweating tests were performed in a hot climatic chamber (45°C, relative humidity <15%, wind speed = 0.8 m·s1, duration 1.5 h). Body temperatures (rectal (Tre) and 10 skin temperatures (Tsk)), sweat rate, and metabolic heat production (Mdot) were studied as well as heart rate (HR). Results showed that modafinil induced at the end of the sweating test higher body temperatures increases (0.50 ± 0.04 versus 0.24 ± 0.05°C (P < 0.01) for deltaTre and 3.64 ± 0.16 versus 3.32 ± 0.16°C (P < 0.05) for deltaTbarsk (mean skin temperature)) and a decrease in sweating rate throughout the heat exposure (P < 0.05) without change in Mdot, leading to a higher body heat storage (P < 0.05). DeltaHR was also increased, especially at the end of the sweating test (17.95 ± 1.49 versus 12.52 ± 1.24 beats/min (P < 0.01)). In conclusion, modafinil induced a slight hyperthermic effect during passive dry heat exposure related to a lower sweat rate, probably by its action on the central nervous system, and this could impair heat tolerance. Key words: modafinil, heat, human, thermoregulation.

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Thermal and metabolic responses of the Australian aborigine exposed to moderate cold in summer

Journal of Applied Physiology ◽

10.1152/jappl.1959.14.4.605 ◽

1959 ◽

Vol 14 (4) ◽

pp. 605-615 ◽

Cited By ~ 68

Author(s):

H. T. Hammel ◽

R. W. Elsner ◽

D. H. Le Messurier ◽

H. T. Andersen ◽

F. A. Milan

Keyword(s):

Metabolic Rate ◽

Cold Exposure ◽

Prolonged Exposure ◽

Metabolic Responses ◽

Body Temperatures ◽

Australian Aborigines ◽

Metabolic Compensation ◽

Australian Aborigine ◽

Body Cooling ◽

And Control

Measurements of thermal and metabolic responses of central Australian aborigines exposed to moderate cold during sleep were repeated during summer and have shown that the small, but important, differences between these natives and control whites exist in summer to the same extent as in winter. The metabolism of the central natives declined continually throughout the night with a Q10 of about two in summer as in winter. Without metabolic compensation, body temperatures of the central natives fell at a greater rate than those of the whites. Measurements of thermal and metabolic responses of a mixed tribal group of tropical Australian aborigines under identical conditions of cold exposure have shown that the average tropical native was intermediate between central natives and control whites. The metabolic rate for tropical natives was 42.8 Cal/m2/hr. compared with 48.7 Cal/m2/hr. for whites and 37.0 Cal/m2/hr. for central natives. We suggest that the Australian aborigine has an inborn ability to tolerate greater body cooling without metabolic compensation which can be increased by prolonged exposure to cold. Submitted on December 3, 1958

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Aerosol anesthesia increases hypercapnic ventilation and breathlessness in laryngectomized humans

Journal of Applied Physiology ◽

10.1152/jappl.1987.63.6.2286 ◽

1987 ◽

Vol 63 (6) ◽

pp. 2286-2292 ◽

Cited By ~ 13

Author(s):

R. D. Hamilton ◽

A. J. Winning ◽

A. Perry ◽

A. Guz

Keyword(s):

Ventilatory Response ◽

Minute Ventilation ◽

Lower Airway ◽

Saline Control ◽

Healthy Male ◽

Analog Scale ◽

Cough Reflex ◽

Vas Scores ◽

Male Subjects ◽

Ventilatory Response To Co2

The effect of local anesthetic aerosol inhalation on the ventilatory response and the sensation of breathlessness to CO2 rebreathing was studied in seven healthy male subjects with permanent tracheal stomas after laryngectomy for carcinoma. Inhalation of bupivacaine aerosol sufficient to abolish the cough reflex to mechanical probing below the carina increased the ventilatory response to CO2 in six of seven subjects compared with saline control. This was achieved by an increase in both respiratory frequency (f) and tidal volume (VT) in four subjects, f in one subject, and VT in one subject. All subjects reported that they were more breathless on rebreathing after bupivacaine aerosol. The six subjects who recorded breathlessness with a visual analog scale (VAS) indicated its onset at a lower minute ventilation (VE) and gave higher VAS scores for equivalent levels of VE after threshold. We conclude that the enhanced CO2 sensitivity and breathlessness on rebreathing after airway anesthesia results from altered lower airway receptor discharge.

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Exercise-Generated Heat Contributes to Thermoregulation by Gambel's Quail in the Cold

Journal of Experimental Biology ◽

10.1242/jeb.171.1.409 ◽

1992 ◽

Vol 171 (1) ◽

pp. 409-422 ◽

Cited By ~ 1

Author(s):

EILEEN ZERBA ◽

GLENN E. WALSBERG

Keyword(s):

Oxygen Consumption ◽

Heat Production ◽

Cold Exposure ◽

Metabolic Heat Production ◽

Energetic Cost ◽

Convective Conditions ◽

Body Temperatures ◽

Ambient Temperatures ◽

Metabolic Heat ◽

Gambel's Quail

The purpose of this study was to investigate the relationship between the allocation of exercise-generated heat and resting metabolic heat production during cold exposure. We tested the hypothesis that, during cold exposure, exercise-generated heat contributes to the fulfillment of the thermostatic requirement. Our assumption was that the thermostatic requirement is higher for exercising than for resting birds in still air because of the disruption of boundary and plumage insulation layers. We predicted that, during moderate exercise, the metabolic heat production of exercising birds would be higher than that for resting birds in still air but would not differ significantly from the metabolic heat generated by resting birds exposed to similar convective conditions. To test our hypothesis we measured whole-animal oxygen consumption of Gambel's quail (Callipepla gambelii Gambel) running in a circular metabolic chamber and at rest in still air at ambient temperatures below the animal's lower critical temperature. We compared these data to previous data for Gambel's quail at rest exposed to wind at a speed equal to the running speed used in our experiments. In addition to oxygen consumption measurements, we measured body temperatures of exercising and resting birds. The data supported our assumption and predictions. (1) Whole-body thermal resistance for exercising birds was lower than that for resting birds in still air, indicating that the thermostatic requirement was higher for exercising birds because of the disruption of boundary and plumage insulation layers. (2) Heat productions of exercising birds were significantly higher than those of resting birds in still air but were not significantly different from the heat productions of resting birds exposed to similar convective conditions. (3) Body temperatures were not significantly different between resting birds in still air and exercising birds. The mean body temperature of exercising birds, however, was 2°C higher than that of resting birds exposed to wind. We concluded that an exercising animal probably does not incur an energetic cost associated with locomotor activity at low ambient temperatures in comparison to an inactive animal exposed to a similar convective regime. Note: Present address: Department of Biology, University of Michigan, Ann Arbor, MI 48109–1048, USA.

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The effects of posture on the metabolic and ventilatory response to low level steady state exercise

Clinical Science ◽

10.1042/cs0710553 ◽

1986 ◽

Vol 71 (5) ◽

pp. 553-558 ◽

Cited By ~ 6

Author(s):

Charles Weissman ◽

Jeffrey Askanazi ◽

S. H. Rosenbaum ◽

Allen I. Hyman ◽

J. Milic-Emili ◽

...

Keyword(s):

Carbon Dioxide ◽

Oxygen Consumption ◽

Ventilatory Response ◽

Minute Ventilation ◽

Carbon Dioxide Production ◽

Normal Male ◽

Breathing Patterns ◽

Low Level ◽

Four Levels ◽

Male Subjects

1. Low level exercise is frequently used to assess cardiac and pulmonary function. This study examines the differences in both metabolic and respiratory patterns between the sitting and supine position. 2. Six normal male subjects were studied in both positions during four levels of exercise (12.5, 25, 37.5 and 50 W). Oxygen consumption (Vo2), carbon dioxide production (Vco2) and minute ventilation (Ve2) were greater when sitting as were the ventilatory equivalents to O2 (Ve2/ Vo2) and CO2 (Ve2/ Vco2). 3. Respiration was compared at equivalent workloads; the greater minute ventilation observed during sitting was due to greater tidal volumes (Vt) and mean inspiratory flows (Vt/Vi,). Expiratory time (Te) was longer and inspiratory duration shorter under most conditions when sitting. 4. When breathing patterns were compared at similar degrees of minute ventilation, Vt, Te and Vt/Ti were greater when sitting, while respiratory frequency (fr) was slower.

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