17β AND 20α-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE RABBIT

Abstract

This communication describes the distribution of NADP-linked 17β- and 20α-hydroxysteroid dehydrogenases in tissues of the New Zealand White rabbit. The substrate specificity of each tissue preparation was assessed using three radioactive steroid substrates: [4-¹⁴C]progesterone, [4-¹⁴C]androst-4-ene-3,17-dione and [4-¹⁴C]oestrone. The tissues listed in Table 1 were homogenized in 0·1 m-phosphate buffer, pH 7·2, and then spun at 25,000g for 30 min. Steroids were incubated with the supernatant fractions, using essentially the conditions of Wiest (1959). Mean values (± s.e.) for the radioactivity recovered after extraction of the incubation products with ether (3×5 vol.) were 86 ± 13, 87 ± 11 and 65 ± 16% for the progesterone, androstenedione and oestrone experiments respectively. Each extract was chromatographed on silica gel G plates (solvent system: chloroform:ethyl acetate, 9:1), and also in a paper chromatographic system of Bush (1952; system A, B₃ and B₁ respectively