Peptone Shock in Fetal Dogs and its Significance in the Metabolism of Histamine

It has previously been shown 1 , 2 that “peptone” shock in dogs, which is produced by the intravenous injection of proteoses, is accompanied by and due to the liberation of histamine from the tissues of the injected animals. The source of, and the reasons for, the storage of histamine in the tissues are only incompletely understood. It seemed, therefore, of interest to determine whether histamine is present in the tissues of fetal animals, and if it is present, to determine whether it can readily be liberated with resulting shock reactions such as occur in adult animals. The studies of Code 3 indicate that the traces of histamine which are normally present in the blood of dogs occur in the cellular elements and not in the plasma. This would imply that the histamine normally circulating in the blood of a pregnant dog would not be accessible to the fetus. As there is no opportunity for the formation of histamine within the fetus by bacterial decomposition of histidine in the fetal intestine, it may be presumed that any histamine occurring in fetal tissues has been produced by local mechanisms such as histidase. 4

The skeletal muscle and liver of a 200 g fetus, obtained by Caesarian section, were assayed for histamine by the method of Best 5 and Best and McHenry. 6 The skeletal muscle assayed less than 0.1 mg histamine base per kilo of tissue. It is, therefore, somewhat doubtful whether any histamine was present. The liver assayed 5.0 mg of histamine base per kilo of tissue.

Three 400 g fetuses, obtained at term, were anesthetized with ether and arranged for the recording of the carotid blood-pressure.