HYDROCORTISONE METABOLISM IN THE PERFUSED ISOLATED RAT LIVER*

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Abstract
IT HAS been abundantly demonstrated that the liver rapidly metabolizes hydrocortisone (compound F) both in vivo and in vitro (1–8). Alterations are effected both in the side chain at C17 and in saturation of double bonds in ring A. Bile has been demonstrated to be an excretory pathway for metabolites of hydrocortisone, but the nature of these substances in bile has not been clearly characterized (8, 9). The work reported here represents data gathered by a study of this problem in the isolated perfused rat liver. MATERIALS AND METHODS A perfusion apparatus for the isolated rat liver was employed which has been described in detail in previous publications (10, 11). Hydrocortisone was determined in plasma by the Silber-Porter method (12). Hydrocortisone was determined in bile by the same chloroform extraction as used in dealing with plasma. When H2SO4 was added however, a cherry-red interfering substance developed in both the blank (extract plus H2SO4) and the sample (extract plus phenylhydrazine plus H2SO4). This substance was regularly found in bile from the perfusion apparatus but not in bile from bile-fistula animals. It was presumably due to products of the hemolysis which occurs to some degree during the perfusion. This interfering material could be eliminated almost completely by interposing the following steps. The chloroform extract of bile was washed with 1 ml. of 15 N H2SO4 in order to develop the colored substance, and then partially neutralized with 7 ml. of 10 per cent Na2CO3. After centrifugation the aqueous layer, which contained the major part of the colored substance, was discarded. The residual chloroform layer was washed with alkali and then processed in the usual fashion, as with plasma extracts. The absorption curve of such bile samples had a sharp peak at 410 mμ.

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