The binding of oestrogens to ovine serum albumin.

Abstract

A major factor in determining the metabolic clearance rate (MCRB) (Tait & Burstein, 1964) of many steroids is the extent to which these may be metabolized by the liver, and those steroids which are present in plasma largely as the unbound or albumin-bound moiety have been shown to have a high splanchnic extraction (Baird, Horton, Longcope & Tait, 1969). In conscious sheep MCRB values for oestradiol-17β and oestrone (Challis, Harrison & Heap, 1973 and in preparation) are similar to or greater than hepatic blood flow (Katz & Bergman, 1969; Paterson & Harrison, 1972), and it seemed probable that in plasma these steroids were largely associated with albumin rather than bound by high affinity proteins. The binding of oestrogens to ovine serum albumin (OSA) and ovine plasma has therefore been studied using an equilibrium dialysis technique (Paterson & Hills, 1967). Tritiated oestrogens (oestradiol-17β, E2β; oestrone, E1