Regulation of circulating dopamine-ß-hydroxylase by disposal pathways: effects of endocrine function
Dopamine-β-hydroxylase (DBH) is unique among the enzymes involved in catecholamine biosynthesis in being the only enzyme whose normal physiology includes (A) release from neuronal cells into the circulatory compartment, and (B) subsequent disposal by extraneuronal mechanisms. Since DBH derives from a defined population of neurons, measurement of circulating DBH activity offers the potential for assessing sympathetic neurotransmitter function at different times and under differing environmental and pathophysiological conditions. The latter rationale provided impetus for many studies on circulating DBH activity and its relationship to sympathetic nervous system function; such studies generally have failed to reveal a reliable correlation between sympathetic function and circulating enzyme activity (Kopin et al., 1976). The level of DBH activity in the circulatory compartment reflects the balance between release from sympathoadrenal cells (i.e. the DBH entry rate) and peripheral degradation (i.e. the DBH metabolic clearance rate, or MCR).
KeywordsDopamine Propylene Glycol Iodide Norepinephrine
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