Lack of hypotensive and brain catecholamine depleting effects by erythro- and threo-alpha-methyl DOPS.

An investigation was carried out to ascertain whether erythro- and threo-alpha-methyl-dihydroxy-phenyl-serine were able of depleting cerebral and peripheral norepinephrine (NE) through their metabolization to alpha-mNE. The results show that the alpha-methyl-aminoacids were decarboxylated only at the periphery and that the threo-form caused depletion in cardiac NE. In any case, both isomers were unable to cross the blood-brain barrier leaving the cerebral NE unaffected. Consequently the use of alpha-mDOPS as alternative tool to alpha-mDOPA in the therapy for hypertension seems unlikely to occur. The results also provide evidence for differences in the pharmacokinetics of the two isomers.