Survival of Hibernating Ground Squirrels (Citellus tridecemlineatus) after Single and Fractionated Doses of Cobalt-60 Gamma Radiation

Abstract

The effects of hibernation on survival after irradiation was studied in thirteen-lined ground squirrels (Citellus tridecemlineatus). The ${\rm LD}_{50(90)}$ for a single dose of60 Co gamma radiation was 1024 rads for ground squirrels irradiated and maintained at 23°C, whereas the ${\rm LD}_{50(90)}$ was 1127 rads for ground squirrels irradiated during hibernation and subsequently maintained in the cold room at 5°C for 3 weeks before they were returned to 23°C. Survival was higher in ground squirrels aroused from hibernation 1 day after an exposure to 1160 rads (79%) than in ground squirrels aroused from hibernation 2 weeks after exposure to 1160 rads (37%). The squirrels that were given 1160 rads at 23°C and maintained at 23°C had 9% survival. When ground squirrels were given two doses of 668 rads, 6 hours apart, survival was greatest (73%) in the hibernating group that was kept in the cold room 3 days before, during the interval between, and for 20 hours after the second dose of gamma rays. The next high...