Low-dose x-radiation damage to capillaries of mouse small intestine. A correlated histologic and microangiographic study.

Abstract

The microangiographic appearance of capillaries of mouse small intestine following exposure to sub-Ielhal whole-body X.radiation has been studied. Adult LAF[ mice exposed to 0 (control), 250, and 500 R were subjected to contact microangiographic procedures using 750 p. thick sections at 4-5, 24, and 120 hrs. later. Correlative histologic sections were obtained on all animals and also from non-injected animals, irradiated and not irradiated. A total of 100 mice was used. After 500 R, damage was clearly detected at 24 hrs.—ragged-appearing capillaries and fewer capillaries were visualized, i.c, capillary bed as a whole was much less patent. No sudi changes had appeared by 4-5 hrs., and by 5 days, recovery had occurred (capillaries appeared normal). No microangiographic differences between control and irradiated specimens were resolvable after 250 K. Capillaries of tissues which demonstrated damage utilizing the microangiograpbic lechnitjue were indistinguishable from controls when studied with conventional histologic methods. These studies show that the capillaries of mouse small intestine are temporarily but appreciably modified by relatively low doses of whole body X-radiation. The capillary damage is correlated, both time-wise and in extent, with the well-known tissue damage caused to small intestine by low doses of x-rays. This suggests, but does not prove, that some of the tissue damage caused by low doses of ionizing radiation arises secondarily following capillary damage.