Site of action of methyldopa in lowering the blood pressure in man.

1. Methyldopa was administered to hypertensive patients in association with two different inhibitors of dopa decarboxylase, one of which, carbidopa, scarcely penetrates the central nervous system while the other, benserazide, penetrates the central nervous system when given in high doses. 2. The evidence suggests that in man, as in animals, the predominant action of methyldopa is mediated by the formation of methyldopamine and methyl-nor-adrenaline within the brain.