Radiation-induced emesis in monkeys

To determine the emesis ED/sub 50/ for /sup 60/Co radiation, 15 male rhesus monkeys were exposed to whole-body radiation doses ranging from 350 to 550 rad midline tissue dose. An up-and-down sequence of exposures was used. Step size between doses was 50 rad, and dose rate was 20 rad/min. There had been no access to food for 1 to 2 h. The ED/sub 50/ +- SE was found to be 446 +- 27 rad. To determine the effect of motion on emesis ED/sub 50/, six more monkeys were exposed to /sup 60/Co radiation as above, except that the chair in which they were seated was oscillated forward and backward 5 to 15/sup 0/ (pitch axis) at a variable rate not exceeding 0.3 Hz. Radioemesis ED/sub 50/ +- SE with motion was 258 +- 19 rad, a value significantly lower (P < 0.01) than for stationary monkeys.