Hypothermia following whole-body heating of mice: effect of heating time and temperature.
We have observed an acute and prolonged lowering of body temperature (hypothermia) following whole body heating (WBH) of mice. This phenomenon of heat-induced hypothermia and the subsequent recovery of normal temperatures have been systematically investigated. The hypothermic period can be characterized by two parameters: Tnadir and a recovery time constant (tau). For treatment temperatures below 41 degrees C and treatment durations of 1 h or less, a mild hypothermia (Tnadir greater than 33 degrees C) and fast recovery (tau less than 1 h) occur. Tnadir and tau vary slightly with treatment temperature and are almost independent of treatment length. At treatment temperatures 41 degrees C and above for up to 1 h, we observed acute hypothermia (Tnadir as low as 28 degrees C) and slow recovery (tau = several hours). This region of prolonged hypothermia is characterized by a rapid change of Tnadir and tau with temperature, and a much less rapid change with treatment duration. The WBH temperature-time range causing prolonged hypothermia is very narrow, and if exceeded results in lethality. Critical lethal temperatures have been estimated for several treatment durations from the time constant data. Post-WBH hypothermia can be minimized by keeping the animals in a 37 degrees C environment. However, we find that neither survivability nor intestinal cell repopulation is enhanced by this procedure.
Wilkinson
D A
DA
Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania 15212.
Burholt
D R
DR
Shrivastava
P N
PN
D000758:Anesthesia / Q000009:adverse effects; D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation; D002455:Cell Division; D005260:Female; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D007035:Hypothermia / Q000209:etiology*; D007421:Intestine, Small / Q000166:cytology; D051379:Mice; D008813:Mice, Inbred ICR; D010424:Pentobarbital / Q000633:toxicity; D013997:Time Factors
D010424:Pentobarbital