Abstract

The plasma metabolic clearance rate (MCRp) of 2-hydroxyestrone was measured in normal young adults by two methods: infusion of unlabeled 2-OHE1 to equilibrium with radioimmunoassay of plasma 2-OHE1 levels, and infusion of [3H]2-OHE1 to equilibrium with measurement of chromatographically purified plasma [3H]2-OHE1. MCR′s were 40–70,000 L/day and 15–50,000 L/day, respectively. This is the highest known MCR for a naturally occurring steroid. The only measurable plasma metabolite of [3H]2-0HE1, co-migrated with 2-methoxyestrone. When [3H]2-0HE1 was incubated with blood samples in vitro, [3H]ξ-methoxyestrone was rapidly formed. Since this MCR is higher than cardiac output, clearance must occur primarily in the blood compartment, probably largely by the action of erythrocyte catechol–0–methyltransferase.

This content is only available as a PDF.
You do not currently have access to this article.