TY - JOUR
T1 - Hypothermia in hypoxic animals
T2 - Mechanisms, mediators, and functional significance
AU - Wood, Stephen C.
AU - Gonzales, Rayna
N1 - Funding Information:
Research of the authors was supported by NIH
PY - 1996
Y1 - 1996
N2 - A basic tenet of biology is that body temperature (T(b)) has a marked effect on oxygen uptake of resting animals. For most animals, the temperature coefficient (Q10) is ≥ 2.5; e.g., resting oxygen uptake changes about 11% per °C change in T(b). An important consequence of this dependence is that hyperthermia could be deleterious for hypoxic animals, particularly for oxygen sensitive organs, e.g., heart and brain. Conversely, a moderate degree of hypothermia could be beneficial during hypoxia. This concept is not new. Forced hypothermia is sometimes used in surgical procedures, particularly for heart and brain surgery. However, in many situations where hypothermia might have benefits, e.g., pediatric intensive care, it is not permitted. This is due in part to dogma and in part to the real and potential disadvantages of hypothermia, even in severely hypoxic animals. Among these is ventricular fibrillation. This is apparently preventable if blood pH is allowed to rise following the 'Buffalo Curve.' Another important disadvantage, were it to occur, is elevation of oxygen demand due to a thermogenic responses. However, at least in some species, the thermogenic response is blunted during hypoxia; e.g., in young rats. Furthermore, even if a thermogenic response occurs, this takes place primarily in muscles (shivering) and brown fat (non-shivering) and not in the O2-sensitive organs, heart and brain. A third disadvantage, for prolonged hypothermia, might be impairment of the immune response, a serious problem if hypoxia is combined with infection. This paper will review four aspects of behavioral fever and hypothermia: the occurrence among animals, the mechanisms and mediators that might trigger behavioral responses, and the functional significance.
AB - A basic tenet of biology is that body temperature (T(b)) has a marked effect on oxygen uptake of resting animals. For most animals, the temperature coefficient (Q10) is ≥ 2.5; e.g., resting oxygen uptake changes about 11% per °C change in T(b). An important consequence of this dependence is that hyperthermia could be deleterious for hypoxic animals, particularly for oxygen sensitive organs, e.g., heart and brain. Conversely, a moderate degree of hypothermia could be beneficial during hypoxia. This concept is not new. Forced hypothermia is sometimes used in surgical procedures, particularly for heart and brain surgery. However, in many situations where hypothermia might have benefits, e.g., pediatric intensive care, it is not permitted. This is due in part to dogma and in part to the real and potential disadvantages of hypothermia, even in severely hypoxic animals. Among these is ventricular fibrillation. This is apparently preventable if blood pH is allowed to rise following the 'Buffalo Curve.' Another important disadvantage, were it to occur, is elevation of oxygen demand due to a thermogenic responses. However, at least in some species, the thermogenic response is blunted during hypoxia; e.g., in young rats. Furthermore, even if a thermogenic response occurs, this takes place primarily in muscles (shivering) and brown fat (non-shivering) and not in the O2-sensitive organs, heart and brain. A third disadvantage, for prolonged hypothermia, might be impairment of the immune response, a serious problem if hypoxia is combined with infection. This paper will review four aspects of behavioral fever and hypothermia: the occurrence among animals, the mechanisms and mediators that might trigger behavioral responses, and the functional significance.
KW - brain
KW - hypothermia
KW - hypoxia
KW - respiration
KW - thermoregulation
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U2 - 10.1016/0305-0491(95)02045-4
DO - 10.1016/0305-0491(95)02045-4
M3 - Article
C2 - 8936041
AN - SCOPUS:0029869562
SN - 0305-0491
VL - 113
SP - 37
EP - 43
JO - Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
JF - Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
IS - 1
ER -