Secretion of 19-hydroxyandrostenedione and 19-hydroxytestosterone by porcine Leydig cells in vitro and in vivo.

19-Hydroxytestosterone and 19-hydroxyandrostenedione have been identified as secretory products of the testes in the mature male domestic pig. Their isolation and identification were made by reverse-phase high-performance liquid chromatography and capillary gas chromatography-mass spectrometry (CGC-MS) of extracts from testicular vein blood and media of incubations with Leydig cells. Blood was collected from veins on the surface of the testes of anaesthetized boars. Collagenase-dispersed Percoll-purified cells (> 90% pure) were incubated (20 x 10(6) cells/flask) with androstenedione (8.75 mumol/l) or [3H]androstenedione (5 x 10(6) c.p.m.) for < 60 min. Steroids were recovered from plasma or media by solid-phase extraction and the unconjugated fractions chromatographed isocratically in two solvent systems (acetonitrile:water, 37:63 (v/v) and methanol:water, 70:30 (v/v)) before CGC-MS analysis. 19-Hydroxytestosterone was present in greater quantities than 19-hydroxyandrostenedione in testicular vein blood; it was also seen as a quantitatively significant metabolite of unlabelled and radioactive androstenedione in the incubation studies. The demonstration of the secretion of 19-hydroxyandrogens from porcine testes thus raises questions concerning the physiological significance of a testicular, rather than an adrenal, secretion of these compounds.