Regional blood flow in rats exposed to supralethal doses of whole body x-irradiation.

Relative blood flow in different organs of the supralethally (3 kR) whole body X-irradiated rat was studied using labeled 15 mu microspheres. Immediately after irradiation blood flow in brain diminishes. From 10 to 20 hrs a phase of increase in blood flowing to many parenchymal organs ensues. A second maximum 45 to 50 hrs and a third one at 60 hrs. In most organs except in brain and liver relative blood flow diminishes before death. The genesis of these changes as signs of a slowly developing shock is discussed.