Lindén I B, Karlsson M, Niemi S, Penttilä A
J Pharm Pharmacol. 1982 Nov;34(11):719-23. doi: 10.1111/j.2042-7158.1982.tb06207.x.
In the rat, 3,4-dihydroxyphenylpyruvic acid (DHPPA) was shown to be transaminated to L-dopa when administered orally concomitantly with L-[3H]dopa. As much as 40% of the serum L-dopa and brain dopamine was shown to be formed via transamination. Moreover, it was shown that DHPPA also caused a so-called L-dopa-sparing effect, i.e. more administered L-dopa reached the circulation and consequently more dopamine reached its target than after administration of L-dopa alone. This effect might be due to an inhibition of the deamination of L-[3H]dopa, since in this case the equilibrium of the transamination reaction will be forced into the L-dopa-forming direction. After administration of [14C]DHPPA alone and together with L-dopa, no differences in the absorption and distribution of radioactivity were found.
在大鼠中，当3,4-二羟基苯丙酮酸（DHPPA）与L-[3H]多巴同时口服给药时，它会被转氨基生成L-多巴。研究表明，高达40%的血清L-多巴和脑多巴胺是通过转氨基作用形成的。此外，研究还表明，DHPPA还会产生所谓的L-多巴节省效应，即与单独给予L-多巴相比，更多给药的L-多巴进入循环，因此更多的多巴胺到达其靶点。这种效应可能是由于L-[3H]多巴脱氨基作用受到抑制，因为在这种情况下，转氨基反应的平衡将被迫朝着生成L-多巴的方向移动。单独给予[14C]DHPPA以及与L-多巴一起给予后，未发现放射性吸收和分布存在差异。
