Biomaterial Database

Ventilatory and metabolic responses to hypoxia during moderate hypothermia in anesthetized rats. 1995

P Frappell, and K Westwood, and M Maskrey

School of Zoology, La Trobe University, Melbourne, Victoria, Australia.

In resting euthermic mammals, hypoxia elicits a hyperventilation that results from a combination of hyperpnea and hypometabolism. Often accompanying the hypoxia-induced hypometabolism is a drop in body temperature. To separate the synergic effects of hypothermia per se from the direct effects of hypoxia on metabolic rate, ventilation (VE), and O2 consumption (VO2) were measured in anesthetized rats fitted with abdominal heat exchangers and maintained at either normothermic (37.5 degrees C) or hypothermic (35 degrees C) body temperatures while exposed to either normoxia or hypoxia (7% O2). Hypothermia induced parallel decreases in VE and VO2, thereby maintaining VE/VO2. Hypoxia resulted in a hyperventilation achieved with the same relative decrease in VO2 and increase in VE in both normothermic and hypothermic rats. The results suggest that 1) the changes in metabolic rate and VE during hypothermia reflect a direct effect of cold and, 2) because of similar levels of hypoxic hyperventilation in the hypothermic and normothermic rats, relative to metabolic rate, respiratory gain has not been depressed in hypothermic rats.

UI	MeSH Term	Description	Entries
D006985	Hyperventilation	A pulmonary ventilation rate faster than is metabolically necessary for the exchange of gases. It is the result of an increased frequency of breathing, an increased tidal volume, or a combination of both. It causes an excess intake of oxygen and the blowing off of carbon dioxide.	Hyperventilations
D007035	Hypothermia	Lower than normal body temperature, especially in warm-blooded animals.	Hypothermia, Accidental,Accidental Hypothermia,Accidental Hypothermias,Hypothermias,Hypothermias, Accidental
D008297	Male		Males
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011659	Pulmonary Gas Exchange	The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.	Exchange, Pulmonary Gas,Gas Exchange, Pulmonary
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D001831	Body Temperature	The measure of the level of heat of a human or animal.	Organ Temperature,Body Temperatures,Organ Temperatures,Temperature, Body,Temperature, Organ,Temperatures, Body,Temperatures, Organ
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000860	Hypoxia	Sub-optimal OXYGEN levels in the ambient air of living organisms.	Anoxia,Oxygen Deficiency,Anoxemia,Deficiency, Oxygen,Hypoxemia,Deficiencies, Oxygen,Oxygen Deficiencies