Morphological response and survival of hepatoma cells during fractionated hyperthermia: effect of glycerol.

Reuber H35 rat hepatoma cells rounded and became spherical during hyperthermia at 42.5 degrees C. When returned to 37 degrees C, the cells recovered and spread out again. As soon as the cells had recovered from the morphologically expressed stress, they expressed tolerance to a second hyperthermia treatment as measured by the same end point. Fractionated hyperthermia made the cells thermotolerant as judged by both the morphological and the cell survival response. Glycerol protected the cells against heat damage as measured by less morphological alteration and decreased cell lethality. Protection depended on the glycerol concentration and maximal protection was observed at 6-8%. After heating in the presence of 7% glycerol, cells expressed thermotolerance at an earlier time than in the absence of glycerol, although the rates of development were approximately similar. Cell survival data and morphological responses showed good correlation.