Cxvi. the Metabolism of Iodobenzene and 5-iodophenylmercapturic Acid in the Rat and the Rabbit. by Norman

THE present work was undertaken as a preliminary step in the investigation of the experimental haemoglobinuria described by Callow and Hele [1927]. These workers found that p-bromoand p-chloro-phenylmercapturic acids, whether given by the mouth or subcutaneously, cause a transient haemoglobinuria in the dog. An attempt was made to find a small animal which would show a similar response to dosage with mercapturic acids. This attempt has not so far been successful; but in the course of the work certain interesting features of the sulphur metabolism of rats and rabbits were displayed. The possibility of mercapturic acid formation from iodobenzene and the effect of dosage with p-iodophenylmercapturic acid were studied in both these animals. The ability of the rabbit to synthesise p-bromophenylmercapturic acid has been shown by Abderhalden and Wertheimer [1925], and some evidence in favour of the occurrence of this synthesis in the rabbit has been brought forward by Rhode [1922], and by Shiple, Muldoon and Sherwin [1924] in the case of the pig. The evidence suggesting a synthesis of mercapturic acid by the rabbit, brought forward by Rhode, was very inconclusive, being founded solely upon the diminished synthesis of ethereal sulphate from monohalogen benzene derivatives when cystine was given simultaneously. Evidence in favour of the oxidation of mercapturic acid to ethereal sulphate has been adduced by Shiple, Muldoon and Sherwin [1924] for the case of the pig, and by Rose, Shiple and Sherwin [1924] for the case of the rabbit. On the other hand, previous work in this laboratory by Coombs and Hele [1927] indicated that this oxidation does not occur in the pig, and a criticism of the conclusions drawn by Sherwin and his co-workers is given in their paper. No case of haemoglobinuria following the administration of a mercapturic acid has been described, other than the observations of Callow and Hele quoted above; nor has haemoglobinuria been obtained, either in the rat or the rabbit, in the course of the present work.