Catecholamine and 5-hydroxyindole metabolism in immunosympathectomized rats.

1. The daily urinary excretion of normetadrenaline, metadrenaline, 4-hydroxy-3-methoxyphenylglycol, 4-hydroxy-3-methoxymandelic acid, dopamine, homovanillic acid, 5-hydroxytryptamine and 5-hydroxyindolylacetic acid has been estimated in the urine of immunosympathectomized and control rats.2. A method is given which allows separate spectrophotometric determination of 4-hydroxy-3-methoxyphenylglycol and 4-hydroxy-3-methoxymandelic acid in the same sample of rat urine. Metadrenaline and normetadrenaline were estimated by a modification of the method of Anton & Sayre (1966).3. Approximately 17% of the 4-hydroxy-3-methoxymandelic acid in rat urine is excreted in the free state, over 60% as a glucuronide conjugate and the remainder as a sulphate conjugate.4. Urinary excretion of 4-hydroxy-3-methoxyphenylglycol was approximately halved in immunosympathectomized rats (P<0.001). 4-Hydroxy-3-methoxymandelic acid output was significantly increased in treated animals (P<0.05) when expressed in terms of body weight. No significant difference was detected for any of the other compounds investigated.5. The results are discussed in the light of previous knowledge of the effect of immunosympathectomy on catecholamine metabolism.