[Combined intraoperative and external irradiation of the celiac artery in the rabbit: the effects on the blood flow of the gastric mucosa].

Aim: To demonstrate changes in gastric mucosal blood flow caused by intraoperative radiotherapy of the celiac artery combined with external radiotherapy of the upper abdomen in a rabbit model. The study was designed to identify a possible correlation between a radiation-induced reduction in mucosal blood flow and the induction of gastric ulcer.
Material and Method: Intraoperative radiation doses of 0 or 30 Gy were given to the celiac artery in rabbits. After a delay of 14 days external radiotherapy of the upper abdomen with 3 x 4 Gy/week to a maximum total dose of 40 Gy was initiated. Gastric mucosal blood flow was assessed by intraventricular injection of radioactively-labelled microspheres (15 microns) followed by measurement of radioactivity in the mucosa. The injections were performed at various time intervals between 2 and 63 days after intraoperative radiation.
Results: Intraoperative radiotherapy, including sham-intraoperative radiation, resulted in a transitory reduction of mucosal blood flow by about 50% of the control value on day 7 (Figure 3). After a temporary recovery by day 14, a marked and permanent reduction in blood flow was assessed after week 6. This time corresponds to the time of development of gastric ulcer.
Conclusions: A relationship between the time of ulcer development and of reduced gastric mucosal blood flow was observed after combined intraoperative and external radiotherapy. The mechanical component of intraoperative treatment has to be emphasized. Reduced blood flow was also seen after intraoperative radiotherapy alone, without an induction of ulcer by this treatment. Hence additional mucosal damage by external radiation must be present for the induction of gastric ulcer.