Effect of irradiation on enzymes of the capillary bed in rat ventricles
Ming Gao, Hiroki Shirato, Kazuo Miyasaka, Tomiyasu Koyama

The effect of localized irradiation on the enzyme activity in rat cardiac capillaries was examined in experiments in which the arteriolar and venular portions of the capillary bed were distinguished by the double-staining method. This method shows that the endothelial cells of the former contain alkaline phosphatase (AP) and those of the latter, dipeptidylpeptidase IV (DPP). At both 1 week and 3 weeks after irradiation with 20 Gy, staining for AP was reduced but staining for DPP was unchanged. The loss of enzyme from the arteriolar portions may be a consequence of the greater radiosensitivity of tissues exposed to high oxygen tension, or it may indicate that AP is less stable than DPP when exposed to irradiation.

Keywords: heart, x-ray irradiation, arteriolar and venular capillary portion, capillary density, endothelial enzymes

Applied Cardiopulmonary Pathophysiology 9: 359-362, 2000

Tomiyasu Koyama, M.D.
Department of Radiology
Hokkaido University
School of Medicine
060 Sapporo
Japan