Abstract

Tyramine, amphetamine, cocaine, chlorpromazine, imipramine, reserpine, guanethidine and Dibenzyline (phenoxybenzamine) markedly reduced the concentration of administered H³- norepinephrine in the heart, spleen and (except for guanethidine) adrenal gland. These drugs lowered the H³-catecholamine concentration to a moderate degree in the liver. Imipramine was the only drug that lowered the H³-catecholamine in the skeletal muscle. The level of H³- normetanephrine was decreased by all these drugs in heart and spleen and in some cases in the adrenal gland and liver.

Tyramine, amphetamine, cocaine, chlorpromazine, imipramine, reserpine, guanethidine and Dibenzyline also elevated the plasma levels of administered H³-norepinephrine for the first 5 minutes. The plasma levels of H³-normetanephrine were also raised to varying degrees. These drugs appear to be acting by preventing the entry and/or the binding of H³-norepinephrine. The following drugs had no significant effect on the tissue and plasma concentration of H³- norepinephrine and H³-normetanephrine: Regitine (phentolamine), dichlorisoproterenol, TM 10 B, hexamethonium and ouabain.

The catechol-O-methyl transferase inhibitor, pyrogallol, elevated the concentration of H³- norepinephrine in heart, spleen, liver and muscle but not the adrenal gland and plasma, and lowered the concentration of H³-normetanephrine in these tissues except the heart and spleen.

Catron, a monoamine oxidase inhibitor, had no effect on the tissue levels of H³-norepinephrine in these tissues (except skeletal muscle) and elevated the concentration of H³- normetanephrine in all tissues.