Histidine Decarboxylase in Hyaline Membrane

During the latter part of pregnancy, the foetal rat produces large quantities of histamine which may be concerned with the growth of the foetus (Kahlson and Rosengren, 1959). Kahlson (1960) reported increased formation of histamine by the human foetus as well: recently Davis (1961) suggested that the antagonism of such excess histamine might account for the beneficial effect of an antihistamine drug (chlorpheniramine) on the respiratory distress of premature infants. It is not unlikely that endogenously-formed histamine participates in the genesis of hyaline membrane, since histamine is believed to regulate the microcirculation (Schayer, 1962), and circulatory changes following hypoxia may play an important role in hyaline membrane formation (Cook, 1962; Wade-Evans, 1962). The histamine formed by the foetal rat is produced in the liver by a specific L-histidine decarboxylase (Kahlson, Rosengren and White, 1959; Telford and West, 1961; Burkhalter, 1962). The present work was undertaken to determine whether abnormally increased histidine decarboxylase activity could be detected in the tissues of infants dying of hyaline membrane disease.