Distribution and accumulation of radioactivity in mice following administration of 14C-8-MOP and 3H-8-MOP: an autoradiographic study.

Mice had 14C-8-MOP and 3H-8-MOP administered in therapeutic doses by gavage and the distribution of radioactivity in the animals was examined by autoradiography of wholebody sections. Animals were examined from 1 hour to 168 h after medication. The highest radioactivity was found 1 h after medication and the same distribution of radioactivity was found independent of time after medication. Very high radioactivity was found in the digestive system, the urine, the gall bladder, and the larger bileducts of the liver. 3H-8-MOP accumulated in the retina whereas 14C-8-MOP was not seen; this difference proves that the substance accumulated in the retina was a metabolite. Repeated medications 3 times weekly for 3 weeks led to accumulation. No additional accumulation was registered after UVA irradiation.