The extra-adrenal synthesis of epinephrine in rats. Possible involvement of dopamine sulfate.

Bilaterally adrenalectomized rats were administered [3H]L-dopa, [3H]DA, and [3H]DASO4. Both [3H]L-dopa and [3H]DASO4 were found to generate [3H]E in the urine and kidney tissues of adrenalectomized rats, whereas [3H]DA did not produce any detectable [3H]E. [3H]CAs in tissues and urine were analyzed by reverse-phase high-performance liquid chromatography. The identities of the [3H]CAs in the urine were further verified by a double-labeling radioenzymatic technique. The results demonstrated that in the rat E can by synthesized outside the adrenals and that DASO4 can serve as an intermediate in such a synthesis. [3H]DASO4 was also converted to [3H]DA and [3H]NE, indicating that it can be metabolized in vivo and could be the source of free DA in urine.