TYROSINE METABOLISM 



317 



Table 2-12 



Effective Doses of Analogs in Inhibiting Kidney Decarboxylase 

 AND Lowering Brain and Heart Norepinephrine in Mice " 



Analog 



ED^o (mg/kg) 



Inhibition 



of renal 



decarboxylase 



Depletion 

 of norepinephrine 



Brain 



Heart 



L-a-Methyl-3,4-dopa 2.63 32 21 



L-a-Methyl-2,3-dopa 1.35 >100 >100 



L-a-Methyl-3-hydroxy-PA 11.7 12 1 



L-a-Methyldopamine No inhibition >100 5 



L-a-Methyl-3-hydroxyphenylethylamine No inhibition 33 0.7 



" Analogs injected intraperitoneally. Kidney decarboxylase activity determined 

 45 min after injection. Doses required to half deplete tissues of norepineplirine in 

 last two columns. Since it has been shown that only the L-isomers are active, results 

 are given on this basis for more convenient comparison. (Data from Porter et al., 1961.) 



100 



5 



TIME (HOURS) 



Fig. 2-5. Inhibition of amino acid decarboxylase in guinea pig tissues by a-methyl- 

 TO-tyrosine injected intraperitoneally at 400 mg/kg. (From Hess et al., 1961.) 



