Polyamines in the small intestine of rats after whole-body irradiation.

The behaviour of polyamines (putrescine, spermidine and spermine) in the small intestine was studied in rats exposed to a single whole-body dose of 3 Gy administered at four different times of the day. Polyamine content decreased a few hours after irradiation but quickly returned to normal values. Putrescine levels reached the lowest values and returned to the control levels later than spermidine and spermine. A temporary increase in spermidine and spermine content was observed from 5 to 20 days. The postirradiation behaviour of the animals exposed at different times of the day showed no important differences. Polyamine modifications were studied in relation to [3H]thymidine uptake and other morphological and biochemical parameters. The results indicate that polyamine content can be used to monitor the damage and recovery phases of radiation injury in the small intestine.