[Accumulation of ephedrine, norephedrine, amphetamine and tyramine labeled with carbon 14 in pigmented and non-pigmented eyes in two races of rats].

The pigmented eyes of non albino rats (PVG) accumulated ephedrine, norephedrine and amphetamine. After 15 min accumulation of ephedrine and amphetamine was larger than of norephedrine. Autoradiographic studies showed that accumulation occurred in melanin containing iris and choroid and also in lacrymal glands which lack melanin. Accumulation of tyramine did not occur in eyes containing melanin. The non pigmented eyes of albino rats did not accumulate ephedrine, amphetamine, norephedrine and tyramine. It appeared that in pigmented eyes melanin was a site of loss of ephedrine, amphetamine and norephedrine; hence a smaller amount of drug will be available for interaction with adrenergic neurons and a smaller mydriatic effect will occur. Accumulation is possible only when metabolism is low, as observed with alpha-methylated amines. The four sympathomimetic amines used did not accumulate in the pigmented skin of black and white rats.