Vascular permeability in the ears of rats after X-irradiation

Abstract

Late fibrosis in normal tissues is a complication which develops gradually after radiotherapy. It may be related to increase in vascular permeability induced by radiation. Plasma proteins leak into irradiated tissue where fibrinogen may be converted into fibrin which is gradually replaced by fibrous tissue. Vascular changes in the rat ear were investigated for six months after X-irradiation. Blood volume and vascular permeability were measured in vivo by monitoring the radioactivity in both irradiated and control ears after intravenous injection of phosphorus 32 labelled red cells and either iodinated (iodine 125) albumin or fibrinogen. After a single dose of 40 Gy there was an early increase in vascular permeability to both albumin and fibrinogen. After 20 Gy permeability to albumin was only increased during desquamation but extra-vascular fibrinogen accumulated at earlier times. Extravascular albumin was removed rapidly from irradiated ears, whereas some residual fibrinogen remained. Vascular p...