The influence of SK & F 64139, a phenylethanolamine-N-methyltransferase inhibitor, on centrally mediated cardiovascular effects of α-methyldopa and clonidine

The inhibitor of phenylethanolamine-N-methyl transferase (PNMT), SK & F 64139 (7,8-dichloro-1,2,3,4-tetrahydroisoquinoline), when given i.v. (5 mg/kg), did not prevent the decrease of blood pressure induced in conscious spontaneously hypertensive rats (SHR) by α-methyldopa (50 mg/kg i.v.). However, i.c.v. administration of SK & F 64139 (5 mg/kg) to conscious SHR reduced both the α-methyldopa-and the clonidine-induced hypotension. Bradycardia in response to clonidine was also prevented by i.c.v. SK & F 64139.