Conversion of 4-Androstene-3β,17β-diol-4-C 14 by Human Adrenals in vitro. ∗

Abstract

Recent interest in the conversion of the Δ^4- 3-hydroxyl to the Δ^4-3-ketone (1,2) has been generated by the isolation of Δ^4-3-hydroxyl compounds(3) or their artifacts from natural sources(4) and by demonstration of the conversion of the Δ^4-3-ketone to the Δ^4-3-hydroxyl under in vitro (5) and in vivo (3) conditions.

The conversion of Δ^4-androstene-3β,17β- diol and its 3a-isomer to testosterone had previously been shown to occur in both rat and chicken liver homogenates (l,2). The conversion of these isomers to testosterone and 4-androstene-3,17-dione occurred in both the supernatant fraction and thrice mashed particulates from the 5000 × g fraction of rat and chicken liver acetone powders. The latter residue fraction, however contained only 30% of the activity of the supernatant. A stimulation by the pyridine nucleotides was also demonstrated.

In addition the conversion of the Δ^4- hydroxyl group to the Δ^4-3-ketone has been shown to occur in the testis tissue of the mouse(6). The present report demonstrates that human adrenal tissue also has the capacity to convert 4-androstene-3β, 17β-diol to testosterone and 4-androstene-3,17-dione.

Methods. A total of 11 g of hyperplastic human female adrenals were homogenized with 80 ml of Krebs-Ringer bicarbonate buffer, pH 7.3, in a Potter-Elvehjem homogenizer. In a series of incubations, 2.5 ml of homogenate were placed in 50 ml Erlenmeyer flasks along with 5 μM ATP, 6 μM NADP, and 1 mg (73,000 cpm) of 4-androstene-3β, 17β-diol-4-C¹⁴ (prepared by Dr. 31. Gut, Worcester Foundation for Experimental Biology). The final volume was 2.8 ml. The flasks were incubated at 37° in a Dubnoff BIetabolic Shaking Incubator (Precision Scientific Co.) under an atmosphere of 95% O₂ and 5% CO₂. The incubator was set at 100 oscillations per minute. Incubations were stopped with 10 volumes of acetone at zero time, 15, 30, 60, and 180 minutes.