[Melatonin biosynthesis in the mammalian retina in dependence of light adaptation (author's transl)]

1. The biosynthesis of melatonin was investigated in retinaextracts of bovine eyes in dependence of light adaptation of the animals. S-adenososyl (Methyl-14C) methionin and acetylserotonin were used as substrates. A higher melatonin-biosynthesis was found in the retina from animals which were adapted to lower illumination. 2. The effect of triamterene on the biosynthesis of melatonin in the retina was examined. An increase of melatonin was found in the presence of the diureticum, which is a pteridine compound, when retinas of animals which were kept under low illumination were investigated. The role of melatoninsynthesis in dark adaptation is discussed and it is pointed to a possible danger of blinding in patients which used triamterene. Furthermore it is suggested that triamterene also increases the melatoninsynthesis in the pineal gland and that this may possibly contribute to an understanding of the effect of the diurecticum.