SERUM DOPAMINE

This research undertaken by Hypro Diagnostics aimed to explore the presence of circulating dopamine-β-hydroxylase, an enzyme crucial for converting dopamine to norepinephrine, within the bloodstream. Through stimulation of isolated perfused adrenal glands and spleens, the study successfully detected dopamine-β-hydroxylase activity in the blood of both humans and rats, utilizing a highly sensitive enzymatic assay. Notably, this activity was identified specifically in the serum and exhibited no association with the formed elements of blood. The serum activity closely mirrored that of purified bovine adrenal dopamine-β-hydroxylase, necessitating ascorbic acid, catalase, fumarate, and oxygen for optimal functionality. Significantly, akin to the adrenal enzyme, the serum activity demonstrated an increase in the presence of cupric ions. The Km values for substrate in human and rat sera closely resembled those in rat adrenal glands and stellate ganglia. In summarizing the findings, the study revealed a mean activity of 2.27±.04 nmoles/ml serum/20 min in the serum of six rats and a range of 96.2 to 284 nmoles/ml/20 min in four normal humans.