Induction of tolerance to hypothermia and hyperthermia by a common mechanism in mammalian cells.
Pretreatment by hypothermic (25 degrees C) cycling (PHC) of attached exponential-phase V79 Chinese hamster cells by Method 4 (24 hr at 25 degrees C + 1.5 hr at 37 degrees C + 24 hr at 25 degrees C + trypsin + 3 hr at 37 degrees C) or by Method 3 (48 hr at 25 degrees C + trypsin + 3 hr at 37 degrees C) make mammalian V79 cells significantly more resistant to 43 degrees C hyperthermia. There is no significant difference in the 43 degrees C curves whether Method 3 or 4 is used for pre-exposure. If pre-exposure at 15 or 10 degrees C, the resistance to hyperthermia is significantly reduced. PHC by Method 4 significantly increases survival of cells exposed to 5 degrees C and, to a lesser extent, to 10 degrees C. The increase in hyper- and hypothermic survival after PHC cannot be accounted for by changes in cell cycle distribution. Heat-shock protein synthesis is not induced by PHC; hence, protection does not result from newly synthesized proteins. When cells are made tolerant to hyperthermia by a pretreatment in 2% DMSO for 24 hr at 37 degrees C (Method 8), the cells are not more resistant to subsequent exposures to hypothermia, either at 5 or 10 degrees C. The results imply that there may be two mechanisms of inducing resistance to hyperthermia, only one of which also confers resistance to hypothermia.
Glofcheski
D J
DJ
Guelph-Waterloo Program for Graduate Work in Physics, University of Waterloo, Ontario, Canada.
Borrelli
M J
MJ
Stafford
D M
DM
Kruuv
J
J
D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D002470:Cell Survival; D003080:Cold Temperature; D006224:Cricetinae; D003412:Cricetulus; D006360:Heat-Shock Proteins / Q000502:physiology*; D006358:Hot Temperature; D066298:In Vitro Techniques; D014176:Protein Biosynthesis
D006360:Heat-Shock Proteins