Ocular kinetics of 8-methoxypsoralen. An experimental study with pigmented and albino rabbits without UVA-stimulation.

Tritiated 8-methoxypsoralen (8-MOP), with radioactivity in the ring system, was injected into both pigmented rabbits and albino rabbits; at 0.5, 1, 2, 4, 6, and 24 h after 8-MOP injection the animals' plasma and ocular radioactivities were determined by liquid scintillation counting. The experiment was done without photostimulation but in incomplete darkness. The plasma radioactivity declined rapidly during the first hour, peak radioactivity occurring in the first samples of vascularized ocular structures taken 0.5 h after the injection. The radioactivity of these tissues generally declined rapidly and similarly in both animal groups. The 1, 2, and 4 h samples of pigmented animals formed an exception; in these the radioactivities in the iris-ciliary body and the retina-choroid of the pigmented animals showed increased activities that were statistically significant, and the plasma radioactivity was exceeded by two to three times. The radioactivities in the internal parts of the eye were lower than in the vascular parts. The radioactivity in the lens reached a peak in the specimens taken 1-2 h after injection and remained at the level of the plasma radioactivity for the rest of the 24 h.