Studies on the characterization and inhibition of rat brain phenylethanolamine N-methyltransferase.

The existence of phenylethanolamine N-methyltransferase (PNMT) activity in the rat brain and spinal cord was confirmed using both substrate specificity and selective inhibitors of the adrenal enzyme as biochemical tools. The enzyme was not generally localized throughout the central nervous system but was found primarily in the brain stem and spinal cord with lesser amounts occurring in the midbrain. No significant PNMT activity was found in markedly inhibited both in vitro and in vivo by low concentrations (doses) of SK&F 64139, a potent inhibitor of the adrenal enzyme.