Enhanced mitotic activity induced by irradiation is abolished by PGI2 pretreatment

It is well known that irradiation may induce pronounced vascular lesions. Experimental studies revealed that irradiation induces an increased mitotic activity. As PGI2 has been claimed to be an antilesional agent, we wondered whether a pretreatment with PGI2 might abolish some of the effects induced by irradiation. 2 Groups of 24 rabbits were studied. 8 Rabbits each were irradiated with either 5 or 10 Gy on an abdominal aortic segment; 8 animals were sham treated. In each of the 3 groups half of the animals (n = 4) received PGI2 and half the buffer vehicle only. It is demonstrated that PGI2 is able to depress the enhanced mitotic activity induced by irradiation. In comparison to the controls, vascular thromboxane formation is decreased, the temporary increase in PGI2-formation by the vessel wall is less pronounced, whereas the conversion of exogenous arachidonic acid is unchanged. It is hypothetized that stable PGI2-analogues given during irradiation may probably prevent at least in part radiation-induced vascular changes and finally radiation-induced vasculopathy; this claim has to be proven in human.